diff --git a/tests/phpunit/CRM/ACL/ListTest.php b/tests/phpunit/CRM/ACL/ListTest.php
index c959bd46aa21..1676f0419de8 100644
--- a/tests/phpunit/CRM/ACL/ListTest.php
+++ b/tests/phpunit/CRM/ACL/ListTest.php
@@ -28,7 +28,7 @@ public function setUp(): void {
   /**
    * general test for the 'view all contacts' permission
    */
-  public function testViewAllPermission() {
+  public function testViewAllPermission(): void {
     // create test contacts
     $contacts = $this->createScenarioPlain();
 
@@ -61,7 +61,7 @@ public function testViewAllPermission() {
   /**
    * general test for the 'view all contacts' permission
    */
-  public function testEditAllPermission() {
+  public function testEditAllPermission(): void {
     // create test contacts
     $contacts = $this->createScenarioPlain();
 
@@ -183,7 +183,7 @@ public function testPermissionByRelation(): void {
   /**
    * Test access based on ACL
    */
-  public function testPermissionByACL() {
+  public function testPermissionByACL(): void {
     $contacts = $this->createScenarioPlain();
 
     // set custom hook
@@ -207,7 +207,7 @@ public function testPermissionByACL() {
   /**
    * Test access with a mix of ACL and relationship
    */
-  public function testPermissionACLvsRelationship() {
+  public function testPermissionACLvsRelationship(): void {
     $contacts = $this->createScenarioRelations();
 
     // set custom hook
@@ -232,7 +232,7 @@ public function testPermissionACLvsRelationship() {
   /**
    * Test access related to the 'access deleted contact' permission
    */
-  public function testPermissionCompare() {
+  public function testPermissionCompare(): void {
     $contacts = $this->createScenarioRelations();
     $contact_index = array_flip($contacts);
 
diff --git a/tests/phpunit/CRM/Activity/BAO/ActivityAssignmentTest.php b/tests/phpunit/CRM/Activity/BAO/ActivityAssignmentTest.php
index c5ff3964f317..cb1ef0e5e2ae 100644
--- a/tests/phpunit/CRM/Activity/BAO/ActivityAssignmentTest.php
+++ b/tests/phpunit/CRM/Activity/BAO/ActivityAssignmentTest.php
@@ -20,7 +20,7 @@ class CRM_Activity_BAO_ActivityAssignmentTest extends CiviUnitTestCase {
   /**
    *  Pass zero as an id and make sure no Assignees are retrieved.
    */
-  public function testGetAssigneeNamesNoId() {
+  public function testGetAssigneeNamesNoId(): void {
     $activity = $this->activityCreate();
     $assignees = CRM_Activity_BAO_ActivityAssignment::getAssigneeNames(0);
 
@@ -30,7 +30,7 @@ public function testGetAssigneeNamesNoId() {
   /**
    *  Pass Null as an id and make sure no Assignees are retrieved.
    */
-  public function testGetAssigneeNamesNullId() {
+  public function testGetAssigneeNamesNullId(): void {
     $activity = $this->activityCreate();
     $assignees = CRM_Activity_BAO_ActivityAssignment::getAssigneeNames(NULL);
 
@@ -40,7 +40,7 @@ public function testGetAssigneeNamesNullId() {
   /**
    *  Pass a known activity id as an id and make sure 1 Assignees is retrieved
    */
-  public function testGetAssigneeNamesOneId() {
+  public function testGetAssigneeNamesOneId(): void {
     $activity = $this->activityCreate();
     $assignees = CRM_Activity_BAO_ActivityAssignment::getAssigneeNames([$activity['id']]);
     $this->assertEquals(count($assignees), 1, '1 assignee names retrieved');
diff --git a/tests/phpunit/CRM/Activity/BAO/ActivityTest.php b/tests/phpunit/CRM/Activity/BAO/ActivityTest.php
index 50392eb0ba4b..1d51f648ac1f 100644
--- a/tests/phpunit/CRM/Activity/BAO/ActivityTest.php
+++ b/tests/phpunit/CRM/Activity/BAO/ActivityTest.php
@@ -56,7 +56,7 @@ public function tearDown(): void {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testCreate() {
+  public function testCreate(): void {
     $contactId = $this->individualCreate();
 
     $params = [
@@ -226,7 +226,7 @@ public function testTargetContactNotAvaliable(): void {
    * Check for errors when viewing a contact's activity tab when there
    * is an activity that doesn't have a target (With Contact).
    */
-  public function testActivitySelectorNoTargets() {
+  public function testActivitySelectorNoTargets(): void {
     $contact_id = $this->individualCreate([], 0, TRUE);
     $activity = $this->callAPISuccess('activity', 'create', [
       'source_contact_id' => $contact_id,
@@ -258,7 +258,7 @@ public function testActivitySelectorNoTargets() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testDeleteActivity() {
+  public function testDeleteActivity(): void {
     $contactId = $this->individualCreate();
     $params = [
       'first_name' => 'liz',
@@ -322,7 +322,7 @@ public function testDeleteActivity() {
   /**
    * Test case for deleteActivityContact() method.
    */
-  public function testDeleteActivityTarget() {
+  public function testDeleteActivityTarget(): void {
     $contactId = $this->individualCreate();
     $params = [
       'first_name' => 'liz',
@@ -408,7 +408,7 @@ public function testDeleteActivityAssignment(): void {
    * Test getActivities BAO method for getting count.
    *
    */
-  public function testGetActivitiesCountForAdminDashboard() {
+  public function testGetActivitiesCountForAdminDashboard(): void {
     // Reset to default
     $this->setShowCaseActivitiesInCore(FALSE);
     $this->setUpForActivityDashboardTests();
@@ -434,7 +434,7 @@ public function testGetActivitiesCountForAdminDashboard() {
    * Test getActivities BAO method for getting count
    *
    */
-  public function testGetActivitiesCountforNonAdminDashboard() {
+  public function testGetActivitiesCountforNonAdminDashboard(): void {
     // Reset to default
     $this->setShowCaseActivitiesInCore(FALSE);
     $this->createTestActivities();
@@ -470,7 +470,7 @@ public function testGetActivitiesCountforNonAdminDashboard() {
    * Test getActivities BAO method for getting count
    *
    */
-  public function testGetActivitiesCountforContactSummary() {
+  public function testGetActivitiesCountforContactSummary(): void {
     // Reset to default
     $this->setShowCaseActivitiesInCore(FALSE);
     $this->createTestActivities();
@@ -502,7 +502,7 @@ public function testGetActivitiesCountforContactSummary() {
   /**
    * CRM-18706 - Test Include/Exclude Activity Filters
    */
-  public function testActivityFilters() {
+  public function testActivityFilters(): void {
     $this->createTestActivities();
     Civi::settings()->set('preserve_activity_tab_filter', 1);
     $this->createLoggedInUser();
@@ -550,7 +550,7 @@ public function testActivityFilters() {
   /**
    * Test getActivities BAO method for getting count
    */
-  public function testGetActivitiesCountforContactSummaryWithNoActivities() {
+  public function testGetActivitiesCountforContactSummaryWithNoActivities(): void {
     $this->createTestActivities();
 
     $params = [
@@ -572,7 +572,7 @@ public function testGetActivitiesCountforContactSummaryWithNoActivities() {
   /**
    * Test getActivities BAO method.
    */
-  public function testGetActivitiesForAdminDashboard() {
+  public function testGetActivitiesForAdminDashboard(): void {
     $this->setShowCaseActivitiesInCore(FALSE);
     $this->setUpForActivityDashboardTests();
     $this->addCaseWithActivity();
@@ -607,7 +607,7 @@ public function testGetActivitiesForAdminDashboard() {
   /**
    * Test getActivities BAO method.
    */
-  public function testGetActivitiesForAdminDashboardNoViewContacts() {
+  public function testGetActivitiesForAdminDashboardNoViewContacts(): void {
     CRM_Core_Config::singleton()->userPermissionClass->permissions = ['access CiviCRM'];
     $this->setUpForActivityDashboardTests();
     foreach ([CRM_Activity_BAO_Activity::getActivities($this->_params)] as $activities) {
@@ -619,7 +619,7 @@ public function testGetActivitiesForAdminDashboardNoViewContacts() {
   /**
    * Test getActivities BAO method.
    */
-  public function testGetActivitiesForAdminDashboardAclLimitedViewContacts() {
+  public function testGetActivitiesForAdminDashboardAclLimitedViewContacts(): void {
     CRM_Core_Config::singleton()->userPermissionClass->permissions = ['access CiviCRM'];
     $this->allowedContacts = [1, 3, 4, 5];
     $this->hookClass->setHook('civicrm_aclWhereClause', [$this, 'aclWhereMultipleContacts']);
@@ -630,7 +630,7 @@ public function testGetActivitiesForAdminDashboardAclLimitedViewContacts() {
   /**
    * Test getActivities BAO method.
    */
-  public function testGetActivitiesforNonAdminDashboard() {
+  public function testGetActivitiesforNonAdminDashboard(): void {
     $this->setShowCaseActivitiesInCore(FALSE);
     $this->createTestActivities();
     $this->addCaseWithActivity();
@@ -685,7 +685,7 @@ public function testGetActivitiesforNonAdminDashboard() {
   /**
    * Test target contact count.
    */
-  public function testTargetCountforContactSummary() {
+  public function testTargetCountforContactSummary(): void {
     $targetCount = 5;
     $contactId = $this->individualCreate();
     $targetContactIDs = [];
@@ -714,7 +714,7 @@ public function testTargetCountforContactSummary() {
   /**
    * Test getActivities BAO method.
    */
-  public function testGetActivitiesforContactSummaryWithSortOptions() {
+  public function testGetActivitiesforContactSummaryWithSortOptions(): void {
     $this->createTestActivities();
     $params = [
       'contact_id' => 9,
@@ -738,7 +738,7 @@ public function testGetActivitiesforContactSummaryWithSortOptions() {
   /**
    * Test getActivities BAO method.
    */
-  public function testGetActivitiesForContactSummary() {
+  public function testGetActivitiesForContactSummary(): void {
     // Reset to default
     $this->setShowCaseActivitiesInCore(FALSE);
     $this->createTestActivities();
@@ -807,7 +807,7 @@ public function testGetActivitiesForContactSummary() {
   /**
    * Test getActivities BAO method.
    */
-  public function testGetActivitiesforContactSummaryWithActivities() {
+  public function testGetActivitiesforContactSummaryWithActivities(): void {
     // Reset to default
     $this->setShowCaseActivitiesInCore(FALSE);
     $this->createTestActivities();
@@ -1145,7 +1145,7 @@ public function getActivityDateData() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testEmailAddressOfActivityCopy() {
+  public function testEmailAddressOfActivityCopy(): void {
     // Case 1: assert the 'From' Email Address of source Actvity Contact ID
     // create activity with source contact ID which has email address
     $assigneeContactId = $this->individualCreate();
@@ -1573,7 +1573,7 @@ public function hook_civicrm_aclWhereClause($type, &$tables, &$whereTables, &$co
     }
   }
 
-  public function testSendEmailWithCaseId() {
+  public function testSendEmailWithCaseId(): void {
     $caseTest = new CiviCaseTestCase();
     $caseTest->setUp();
     // Create a contact and contactDetails array.
diff --git a/tests/phpunit/CRM/Activity/BAO/ActivityTypeTest.php b/tests/phpunit/CRM/Activity/BAO/ActivityTypeTest.php
index e0a531f3365b..cfb187cd5744 100644
--- a/tests/phpunit/CRM/Activity/BAO/ActivityTypeTest.php
+++ b/tests/phpunit/CRM/Activity/BAO/ActivityTypeTest.php
@@ -8,7 +8,7 @@ class CRM_Activity_BAO_ActivityTypeTest extends CiviUnitTestCase {
   /**
    * Test ActivityType
    */
-  public function testActivityType() {
+  public function testActivityType(): void {
     $actParams = [
       'option_group_id' => 'activity_type',
       'name' => 'abc123',
diff --git a/tests/phpunit/CRM/Activity/Form/ActivityTest.php b/tests/phpunit/CRM/Activity/Form/ActivityTest.php
index 1606517e8f9d..5486c7c751ee 100644
--- a/tests/phpunit/CRM/Activity/Form/ActivityTest.php
+++ b/tests/phpunit/CRM/Activity/Form/ActivityTest.php
@@ -29,7 +29,7 @@ public function setUp():void {
     $this->source = $this->individualCreate();
   }
 
-  public function testActivityCreate() {
+  public function testActivityCreate(): void {
     Civi::settings()->set('activity_assignee_notification', TRUE);
     //Reset filter to none.
     Civi::settings()->set('do_not_notify_assignees_for', []);
@@ -61,7 +61,7 @@ public function testActivityCreate() {
     $this->assertEmpty($msg);
   }
 
-  public function testActivityDelete() {
+  public function testActivityDelete(): void {
     // Set the parameters of the test.
     $numberOfSingleActivitiesToCreate = 3;
     $numberOfRepeatingActivitiesToCreate = 6;
@@ -158,7 +158,7 @@ public function testActivityDelete() {
   /**
    * Test deleting an activity that has an attachment.
    */
-  public function testActivityDeleteWithAttachment() {
+  public function testActivityDeleteWithAttachment(): void {
     $loggedInUser = $this->createLoggedInUser();
     // Create an activity
     $activity = $this->callAPISuccess('Activity', 'create', [
@@ -242,7 +242,7 @@ private function deleteActivity($activityId, $mode = NULL) {
   /**
    * This is a bit messed up having a variable called name that means label but we don't want to fix it because it's a form member variable _activityTypeName that might be used in form hooks, so just make sure it doesn't flip between name and label. dev/core#1116
    */
-  public function testActivityTypeNameIsReallyLabel() {
+  public function testActivityTypeNameIsReallyLabel(): void {
     $form = new CRM_Activity_Form_Activity();
 
     // the actual value is irrelevant we just need something for the tested function to act on
@@ -276,7 +276,7 @@ public function testActivityTypeNameIsReallyLabel() {
    *
    * See also testActivityTypeNameIsReallyLabel()
    */
-  public function testActivityTypeAssignment() {
+  public function testActivityTypeAssignment(): void {
     $form = new CRM_Activity_Form_Activity();
 
     $form->_currentlyViewedContactId = $this->source;
diff --git a/tests/phpunit/CRM/Activity/Form/SearchTest.php b/tests/phpunit/CRM/Activity/Form/SearchTest.php
index a50099c5bfc5..696068edd83f 100644
--- a/tests/phpunit/CRM/Activity/Form/SearchTest.php
+++ b/tests/phpunit/CRM/Activity/Form/SearchTest.php
@@ -79,7 +79,7 @@ public function testSearch(): void {
   /**
    * Test the Qill for activity Date time.
    */
-  public function testQill() {
+  public function testQill(): void {
     foreach ($this->getSearchCriteria() as $test_name => $data) {
       $selector = new CRM_Activity_Selector_Search($data['search_criteria']);
       $this->assertEquals($data['expected_qill'], $selector->getQILL(), "Failed for data set: $test_name");
diff --git a/tests/phpunit/CRM/Activity/Form/Task/PDFTest.php b/tests/phpunit/CRM/Activity/Form/Task/PDFTest.php
index bebdcbf741b5..6397d46b929d 100644
--- a/tests/phpunit/CRM/Activity/Form/Task/PDFTest.php
+++ b/tests/phpunit/CRM/Activity/Form/Task/PDFTest.php
@@ -92,7 +92,7 @@ protected function getActivityTokens(): array {
     ];
   }
 
-  public function testCreateDocumentCustomFieldTokens() {
+  public function testCreateDocumentCustomFieldTokens(): void {
     // Set up custom group, and field
     // returns custom_group_id, custom_field_id, custom_field_option_group_id, custom_field_group_options
     $cg = $this->entityCustomGroupWithSingleStringMultiSelectFieldCreate("MyCustomField", "ActivityTest.php");
diff --git a/tests/phpunit/CRM/Activity/Page/AJAXTest.php b/tests/phpunit/CRM/Activity/Page/AJAXTest.php
index d4d30f66a817..7f6b3dee305a 100644
--- a/tests/phpunit/CRM/Activity/Page/AJAXTest.php
+++ b/tests/phpunit/CRM/Activity/Page/AJAXTest.php
@@ -34,7 +34,7 @@ public function setUp(): void {
    * passed to the function this test is testing. So there's no form or ajax
    * being tested here, just the final act of filing the activity.
    */
-  public function testConvertToCaseActivity() {
+  public function testConvertToCaseActivity(): void {
     $activity = $this->callAPISuccess('Activity', 'create', [
       'source_contact_id' => $this->loggedInUser,
       'activity_type_id' => 'Meeting',
@@ -71,7 +71,7 @@ public function testConvertToCaseActivity() {
   /**
    * Similar to testConvertToCaseActivity above but for copy-to-case.
    */
-  public function testCopyToCase() {
+  public function testCopyToCase(): void {
     $case1 = $this->callAPISuccess('Case', 'create', [
       'contact_id' => $this->target,
       'case_type_id' => 'housing_support',
@@ -125,7 +125,7 @@ public function testCopyToCase() {
   /**
    * Similar to testCopyToCase above but for move-to-case.
    */
-  public function testMoveToCase() {
+  public function testMoveToCase(): void {
     $case1 = $this->callAPISuccess('Case', 'create', [
       'contact_id' => $this->target,
       'case_type_id' => 'housing_support',
@@ -179,7 +179,7 @@ public function testMoveToCase() {
   /**
    * Check if the selected filters are saved.
    */
-  public function testPreserveFilters() {
+  public function testPreserveFilters(): void {
     \Civi::settings()->set('preserve_activity_tab_filter', '1');
 
     // Simulate visiting activity tab with all the filters set to something
diff --git a/tests/phpunit/CRM/Bridge/OG/DrupalTest.php b/tests/phpunit/CRM/Bridge/OG/DrupalTest.php
index 02cb1722c519..deb6e9ec9c0d 100644
--- a/tests/phpunit/CRM/Bridge/OG/DrupalTest.php
+++ b/tests/phpunit/CRM/Bridge/OG/DrupalTest.php
@@ -45,7 +45,7 @@ class CRM_Bridge_OG_DrupalTest extends CiviUnitTestCase {
   /**
    * Test that one (ane only one) role (option value) is deleted by the updateCiviACLRole function
    */
-  public function testACLRoleDeleteFunctionality() {
+  public function testACLRoleDeleteFunctionality(): void {
     $optionGroup = civicrm_api('OptionGroup', 'Get', [
       'version' => 3,
       'name' => 'acl_role',
diff --git a/tests/phpunit/CRM/Campaign/BAO/CampaignTest.php b/tests/phpunit/CRM/Campaign/BAO/CampaignTest.php
index b5627adff186..47b6046e8915 100644
--- a/tests/phpunit/CRM/Campaign/BAO/CampaignTest.php
+++ b/tests/phpunit/CRM/Campaign/BAO/CampaignTest.php
@@ -17,7 +17,7 @@
  */
 class CRM_Campaign_BAO_CampaignTest extends CiviUnitTestCase {
 
-  public function testCampaignSummary() {
+  public function testCampaignSummary(): void {
     $loggedInContact = $this->createLoggedInUser();
     $contact = $this->individualCreate();
     $this->callAPISuccess('Campaign', 'create', [
diff --git a/tests/phpunit/CRM/Campaign/BAO/QueryTest.php b/tests/phpunit/CRM/Campaign/BAO/QueryTest.php
index 21ecce3e1a37..9067456f7a29 100644
--- a/tests/phpunit/CRM/Campaign/BAO/QueryTest.php
+++ b/tests/phpunit/CRM/Campaign/BAO/QueryTest.php
@@ -18,7 +18,7 @@
  */
 class CRM_Campaign_BAO_QueryTest extends CiviUnitTestCase {
 
-  public function testCampaignVoterClause() {
+  public function testCampaignVoterClause(): void {
     $loggedInContact = $this->createLoggedInUser();
     $contact = $this->individualCreate();
     $activityType = CRM_Core_PseudoConstant::getKey('CRM_Activity_BAO_Activity', 'activity_type_id', 'survey');
diff --git a/tests/phpunit/CRM/Case/BAO/CaseTest.php b/tests/phpunit/CRM/Case/BAO/CaseTest.php
index bf1adf3c6584..40a3ab39aa8f 100644
--- a/tests/phpunit/CRM/Case/BAO/CaseTest.php
+++ b/tests/phpunit/CRM/Case/BAO/CaseTest.php
@@ -64,7 +64,7 @@ protected function tearDown(): void {
     parent::tearDown();
   }
 
-  public function testAddCaseToContact() {
+  public function testAddCaseToContact(): void {
     $this->createLoggedInUser();
     $params = [
       'case_id' => 1,
@@ -239,7 +239,7 @@ public function testSortByCaseContact(): void {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testActiveCaseRole() {
+  public function testActiveCaseRole(): void {
     $individual = $this->individualCreate();
     $caseObj = $this->createCase($individual);
     $caseId = $caseObj->id;
@@ -251,7 +251,7 @@ public function testActiveCaseRole() {
   /**
    * Test that case count is zero for logged in user for user's inactive role.
    */
-  public function testInactiveCaseRole() {
+  public function testInactiveCaseRole(): void {
     $individual = $this->individualCreate();
     $caseObj = $this->createCase($individual);
     $caseId = $caseObj->id;
@@ -260,12 +260,12 @@ public function testInactiveCaseRole() {
     $this->assertCasesOfUser($loggedInUser, $caseId, 0);
   }
 
-  public function testGetCaseType() {
+  public function testGetCaseType(): void {
     $caseTypeLabel = CRM_Case_BAO_Case::getCaseType(1);
     $this->assertEquals('Housing Support', $caseTypeLabel);
   }
 
-  public function testRetrieveCaseIdsByContactId() {
+  public function testRetrieveCaseIdsByContactId(): void {
     $caseIds = CRM_Case_BAO_Case::retrieveCaseIdsByContactId(3, FALSE, 'housing_support');
     $this->assertEquals([1], $caseIds);
   }
@@ -273,7 +273,7 @@ public function testRetrieveCaseIdsByContactId() {
   /**
    * Test that all custom files are migrated to new case when case is assigned to new client.
    */
-  public function testCaseReassignForCustomFiles() {
+  public function testCaseReassignForCustomFiles(): void {
     $individual = $this->individualCreate();
     $customGroup = $this->customGroupCreate(array(
       'extends' => 'Case',
@@ -348,7 +348,7 @@ public function testCaseReassignForCustomFiles() {
    *   $this->assertEquals(1, $cases[1]['case_type_id']);
    * }
    */
-  public function testGetCasesSummary() {
+  public function testGetCasesSummary(): void {
     $cases = CRM_Case_BAO_Case::getCasesSummary();
     $this->assertEquals(1, $cases['rows']['Housing Support']['Ongoing']['count']);
   }
@@ -357,7 +357,7 @@ public function testGetCasesSummary() {
    * Test that getRelatedCases() returns the other case when you create a
    * Link Cases activity on one of the cases.
    */
-  public function testGetRelatedCases() {
+  public function testGetRelatedCases(): void {
     $loggedInUser = $this->createLoggedInUser();
     // create some cases
     $client_id_1 = $this->individualCreate([], 0);
@@ -398,7 +398,7 @@ public function testGetRelatedCases() {
   /**
    * Test various things after a case is closed.
    */
-  public function testCaseClosure() {
+  public function testCaseClosure(): void {
     $loggedInUser = $this->createLoggedInUser();
     $client_id = $this->individualCreate();
     $caseObj = $this->createCase($client_id, $loggedInUser);
@@ -508,7 +508,7 @@ public function testCaseClosure() {
   /**
    * Test getGlobalContacts
    */
-  public function testGetGlobalContacts() {
+  public function testGetGlobalContacts(): void {
     //Add contact to case resource.
     $caseResourceContactID = $this->individualCreate();
     $this->callAPISuccess('GroupContact', 'create', [
@@ -683,7 +683,7 @@ public function testMaxInstances(): void {
    * At the time this test was written this test would fail, demonstrating
    * one problem with name vs label.
    */
-  public function testCreateCaseWithChangedManagerLabel() {
+  public function testCreateCaseWithChangedManagerLabel(): void {
     // We could just assume the relationship that gets created has
     // relationship_type_id = 1, but let's create a case, see what the
     // id is, then do our actual test.
@@ -743,7 +743,7 @@ public function testCreateCaseWithChangedManagerLabel() {
    * Test change case status with linked cases choosing the option to
    * update the linked cases.
    */
-  public function testChangeCaseStatusLinkedCases() {
+  public function testChangeCaseStatusLinkedCases(): void {
     $loggedInUser = $this->createLoggedInUser();
     $clientId1 = $this->individualCreate();
     $clientId2 = $this->individualCreate();
@@ -1165,7 +1165,7 @@ public function caseActivityQueryProvider(): array {
    * Test that if you only have "my cases" permission you can still view
    * Manage Case for **closed** cases of yours.
    */
-  public function testCanViewClosedCaseAsNonAdmin() {
+  public function testCanViewClosedCaseAsNonAdmin(): void {
     $loggedInUser = $this->createLoggedInUser();
     CRM_Core_Config::singleton()->userPermissionClass->permissions = [
       'access CiviCRM',
@@ -1202,7 +1202,7 @@ public function testCanViewClosedCaseAsNonAdmin() {
   /**
    * Test a high number of assigned case roles.
    */
-  public function testGoingTo11() {
+  public function testGoingTo11(): void {
     $loggedInUser = $this->createLoggedInUser();
     $individual = $this->individualCreate();
     $caseObj = $this->createCase($individual, $loggedInUser);
@@ -1234,7 +1234,7 @@ public function testGoingTo11() {
    * Test that creating a regular activity with a subject including `[case #X]`
    * gets filed on case X.
    */
-  public function testFileOnCaseBySubject() {
+  public function testFileOnCaseBySubject(): void {
     $loggedInUserId = $this->createLoggedInUser();
     $clientId = $this->individualCreate();
     $caseObj = $this->createCase($clientId, $loggedInUserId);
@@ -1271,7 +1271,7 @@ public function testFileOnCaseBySubject() {
   /**
    * Same as testFileOnCaseBySubject but editing an existing non-case activity
    */
-  public function testFileOnCaseByEditingSubject() {
+  public function testFileOnCaseByEditingSubject(): void {
     $loggedInUserId = $this->createLoggedInUser();
     $clientId = $this->individualCreate();
     $caseObj = $this->createCase($clientId, $loggedInUserId);
@@ -1313,7 +1313,7 @@ public function testFileOnCaseByEditingSubject() {
   /**
    * Basic case create test with an Org client
    */
-  public function testOrgClient() {
+  public function testOrgClient(): void {
     $loggedInUserId = $this->createLoggedInUser();
     $clientId = $this->organizationCreate();
     $caseObj = $this->createCase($clientId, $loggedInUserId);
@@ -1332,7 +1332,7 @@ public function testOrgClient() {
   /**
    * Test getRelatedAndGlobalContacts()
    */
-  public function testGetRelatedAndGlobalContacts() {
+  public function testGetRelatedAndGlobalContacts(): void {
     $loggedInUserId = $this->createLoggedInUser();
     $clientId = $this->individualCreate(['first_name' => 'Cli', 'last_name' => 'Ent'], 0, TRUE);
     $caseObj = $this->createCase($clientId, $loggedInUserId);
@@ -1382,7 +1382,7 @@ public function testGetRelatedAndGlobalContacts() {
    * Test that if there's only recently performed activities in the system
    * and no future ones then it still shows on dashboard.
    */
-  public function testOnlyRecent() {
+  public function testOnlyRecent(): void {
     $loggedInUserId = $this->createLoggedInUser();
     $clientId = $this->individualCreate([], 0, TRUE);
     // old start date so there's no upcoming
diff --git a/tests/phpunit/CRM/Case/BAO/CaseTypeForkTest.php b/tests/phpunit/CRM/Case/BAO/CaseTypeForkTest.php
index e77dbda7d466..42c346cdd4cd 100644
--- a/tests/phpunit/CRM/Case/BAO/CaseTypeForkTest.php
+++ b/tests/phpunit/CRM/Case/BAO/CaseTypeForkTest.php
@@ -20,7 +20,7 @@ public function tearDown(): void {
   /**
    * Test Manager contact is correctly assigned via case type def.
    */
-  public function testManagerContact() {
+  public function testManagerContact(): void {
     $caseTypeId = CRM_Core_DAO::getFieldValue('CRM_Case_DAO_CaseType', 'ForkableCaseType', 'id', 'name');
     $this->assertTrue(is_numeric($caseTypeId) && $caseTypeId > 0);
 
@@ -45,7 +45,7 @@ public function testManagerContact() {
   /**
    * Edit the definition of ForkableCaseType.
    */
-  public function testForkable() {
+  public function testForkable(): void {
     $caseTypeId = CRM_Core_DAO::getFieldValue('CRM_Case_DAO_CaseType', 'ForkableCaseType', 'id', 'name');
     $this->assertTrue(is_numeric($caseTypeId) && $caseTypeId > 0);
 
@@ -80,7 +80,7 @@ public function testForkable() {
   /**
    * Attempt to edit the definition of UnforkableCaseType. This fails.
    */
-  public function testUnforkable() {
+  public function testUnforkable(): void {
     $caseTypeId = CRM_Core_DAO::getFieldValue('CRM_Case_DAO_CaseType', 'UnforkableCaseType', 'id', 'name');
     $this->assertTrue(is_numeric($caseTypeId) && $caseTypeId > 0);
     $this->assertDBNull('CRM_Case_BAO_CaseType', $caseTypeId, 'definition', 'id', "Should not have DB-based definition");
diff --git a/tests/phpunit/CRM/Case/BAO/QueryTest.php b/tests/phpunit/CRM/Case/BAO/QueryTest.php
index 54f83a133a5f..9f4c168db714 100644
--- a/tests/phpunit/CRM/Case/BAO/QueryTest.php
+++ b/tests/phpunit/CRM/Case/BAO/QueryTest.php
@@ -19,7 +19,7 @@ class CRM_Case_BAO_QueryTest extends CiviCaseTestCase {
    *  - case_activity_status_id
    *  - case_activity_medium_id
    */
-  public function testWhereClauseSingle() {
+  public function testWhereClauseSingle(): void {
     $params = [
       0 => [
         0 => 'case_activity_type',
@@ -58,7 +58,7 @@ public function testWhereClauseSingle() {
   /**
    * Test the qill for a find cases search.
    */
-  public function testFindCasesQuery() {
+  public function testFindCasesQuery(): void {
     $params = [
       [
         0 => 'case_type_id',
diff --git a/tests/phpunit/CRM/Case/Form/SearchTest.php b/tests/phpunit/CRM/Case/Form/SearchTest.php
index e8166be7c917..18173feeffe1 100644
--- a/tests/phpunit/CRM/Case/Form/SearchTest.php
+++ b/tests/phpunit/CRM/Case/Form/SearchTest.php
@@ -22,7 +22,7 @@ public function setUp():void {
    * variable so it has a typo in CRM_Case_Form_Search::preProcess(), and then
    * this test will throw an exception.
    */
-  public function testOpeningFindCaseForm() {
+  public function testOpeningFindCaseForm(): void {
     $form = new CRM_Case_Form_Search();
     $form->controller = new CRM_Case_Controller_Search('Find Cases');
 
diff --git a/tests/phpunit/CRM/Case/PseudoConstantTest.php b/tests/phpunit/CRM/Case/PseudoConstantTest.php
index 8a2997cb8335..c219bed2b05f 100644
--- a/tests/phpunit/CRM/Case/PseudoConstantTest.php
+++ b/tests/phpunit/CRM/Case/PseudoConstantTest.php
@@ -7,7 +7,7 @@
  */
 class CRM_Case_PseudoConstantTest extends CiviCaseTestCase {
 
-  public function testCaseType() {
+  public function testCaseType(): void {
     CRM_Core_PseudoConstant::flush();
     $caseTypes = CRM_Case_PseudoConstant::caseType();
     $expectedTypes = [
diff --git a/tests/phpunit/CRM/Case/WorkflowMessage/CaseActivityTest.php b/tests/phpunit/CRM/Case/WorkflowMessage/CaseActivityTest.php
index fbe47bb84249..346503aa8090 100644
--- a/tests/phpunit/CRM/Case/WorkflowMessage/CaseActivityTest.php
+++ b/tests/phpunit/CRM/Case/WorkflowMessage/CaseActivityTest.php
@@ -21,7 +21,7 @@ public function getWorkflowClass(): string {
     return CRM_Case_WorkflowMessage_CaseActivity::class;
   }
 
-  public function testAdhocClassEquiv() {
+  public function testAdhocClassEquiv(): void {
     $examples = \Civi\Api4\ExampleData::get(0)
       ->setSelect(['name', 'data'])
       ->addWhere('name', 'IN', ['workflow/case_activity/CaseAdhocExample', 'workflow/case_activity/CaseModelExample'])
@@ -38,7 +38,7 @@ public function testAdhocClassEquiv() {
    *
    * To see this, we take all the example data and use it with diff constructors.
    */
-  public function testConstructorEquivalence() {
+  public function testConstructorEquivalence(): void {
     $examples = $this->findExamples()->execute()->indexBy('name')->column('data');
     $this->assertTrue(count($examples) >= 1, 'Must have at least one example data-set');
     foreach ($examples as $example) {
@@ -52,7 +52,7 @@ public function testConstructorEquivalence() {
    * @throws \CRM_Core_Exception
    * @throws \Civi\API\Exception\UnauthorizedException
    */
-  public function testExampleGet() {
+  public function testExampleGet(): void {
     $file = \Civi::paths()->getPath('[civicrm.root]/tests/phpunit/CRM/Case/WorkflowMessage/CaseActivity/CaseModelExample.php');
     $name = 'workflow/case_activity/CaseModelExample';
 
diff --git a/tests/phpunit/CRM/Case/XMLProcessor/ProcessTest.php b/tests/phpunit/CRM/Case/XMLProcessor/ProcessTest.php
index 4631684f66b2..6799b691aa4c 100644
--- a/tests/phpunit/CRM/Case/XMLProcessor/ProcessTest.php
+++ b/tests/phpunit/CRM/Case/XMLProcessor/ProcessTest.php
@@ -222,7 +222,7 @@ protected function setupActivityDefinitions() {
    * Tests the creation of activities where the default assignee should be the
    * target contact's instructor. Beto is the instructor for Ana.
    */
-  public function testCreateActivityWithDefaultContactByRelationship() {
+  public function testCreateActivityWithDefaultContactByRelationship(): void {
     $relationship = $this->relationships['ana_is_pupil_of_beto'];
     $this->activityTypeXml->default_assignee_type = $this->defaultAssigneeOptionsValues['BY_RELATIONSHIP'];
     $this->activityTypeXml->default_assignee_relationship = "{$relationship['type_id']}_b_a";
@@ -236,7 +236,7 @@ public function testCreateActivityWithDefaultContactByRelationship() {
    * end up being a contact from another case where it has the same client
    * and relationship.
    */
-  public function testCreateActivityWithDefaultContactByRelationshipTwoCases() {
+  public function testCreateActivityWithDefaultContactByRelationshipTwoCases(): void {
     /*
     At this point the stock setup looks like this:
     Case 1: no roles assigned
@@ -326,7 +326,7 @@ public function testCreateActivityWithDefaultContactByRelationshipTwoCases() {
    * Tests when the default assignee relationship exists, but in the other direction only.
    * Ana is a pupil, but has no pupils related to her.
    */
-  public function testCreateActivityWithDefaultContactByRelationshipMissing() {
+  public function testCreateActivityWithDefaultContactByRelationshipMissing(): void {
     $relationship = $this->relationships['ana_is_pupil_of_beto'];
     $this->activityTypeXml->default_assignee_type = $this->defaultAssigneeOptionsValues['BY_RELATIONSHIP'];
     $this->activityTypeXml->default_assignee_relationship = "{$relationship['type_id']}_a_b";
@@ -339,7 +339,7 @@ public function testCreateActivityWithDefaultContactByRelationshipMissing() {
    * Tests when the the default assignee relationship exists and is a bidirectional
    * relationship. Ana and Carlos are spouses.
    */
-  public function testCreateActivityWithDefaultContactByRelationshipBidirectional() {
+  public function testCreateActivityWithDefaultContactByRelationshipBidirectional(): void {
     $relationship = $this->relationships['ana_is_spouse_of_carlos'];
     $this->activityParams['clientID'] = $this->contacts['carlos'];
     $this->activityTypeXml->default_assignee_type = $this->defaultAssigneeOptionsValues['BY_RELATIONSHIP'];
@@ -353,7 +353,7 @@ public function testCreateActivityWithDefaultContactByRelationshipBidirectional(
    * Tests when the default assignee relationship does not exist. Ana is not an
    * employee for anyone.
    */
-  public function testCreateActivityWithDefaultContactByRelationButTheresNoRelationship() {
+  public function testCreateActivityWithDefaultContactByRelationButTheresNoRelationship(): void {
     $relationship = $this->relationships['unassigned_employee'];
     $this->activityTypeXml->default_assignee_type = $this->defaultAssigneeOptionsValues['BY_RELATIONSHIP'];
     $this->activityTypeXml->default_assignee_relationship = "{$relationship['type_id']}_b_a";
@@ -365,7 +365,7 @@ public function testCreateActivityWithDefaultContactByRelationButTheresNoRelatio
   /**
    * Tests the creation of activities with default assignee set to a specific contact.
    */
-  public function testCreateActivityAssignedToSpecificContact() {
+  public function testCreateActivityAssignedToSpecificContact(): void {
     $this->activityTypeXml->default_assignee_type = $this->defaultAssigneeOptionsValues['SPECIFIC_CONTACT'];
     $this->activityTypeXml->default_assignee_contact = $this->contacts['carlos'];
 
@@ -377,7 +377,7 @@ public function testCreateActivityAssignedToSpecificContact() {
    * Tests the creation of activities with default assignee set to a specific contact,
    * but the contact does not exist.
    */
-  public function testCreateActivityAssignedToNonExistantSpecificContact() {
+  public function testCreateActivityAssignedToNonExistantSpecificContact(): void {
     $this->activityTypeXml->default_assignee_type = $this->defaultAssigneeOptionsValues['SPECIFIC_CONTACT'];
     $this->activityTypeXml->default_assignee_contact = 987456321;
 
@@ -389,7 +389,7 @@ public function testCreateActivityAssignedToNonExistantSpecificContact() {
    * Tests the creation of activities with the default assignee being the one
    * creating the case's activity.
    */
-  public function testCreateActivityAssignedToUserCreatingTheCase() {
+  public function testCreateActivityAssignedToUserCreatingTheCase(): void {
     $this->activityTypeXml->default_assignee_type = $this->defaultAssigneeOptionsValues['USER_CREATING_THE_CASE'];
 
     $this->process->createActivity($this->activityTypeXml, $this->activityParams);
@@ -399,7 +399,7 @@ public function testCreateActivityAssignedToUserCreatingTheCase() {
   /**
    * Tests the creation of activities when the default assignee is set to NONE.
    */
-  public function testCreateActivityAssignedNoUser() {
+  public function testCreateActivityAssignedNoUser(): void {
     $this->activityTypeXml->default_assignee_type = $this->defaultAssigneeOptionsValues['NONE'];
 
     $this->process->createActivity($this->activityTypeXml, $this->activityParams);
@@ -409,7 +409,7 @@ public function testCreateActivityAssignedNoUser() {
   /**
    * Tests the creation of activities when the default assignee is set to NONE.
    */
-  public function testCreateActivityWithNoDefaultAssigneeOption() {
+  public function testCreateActivityWithNoDefaultAssigneeOption(): void {
     $this->process->createActivity($this->activityTypeXml, $this->activityParams);
     $this->assertActivityAssignedToContactExists(NULL);
   }
@@ -555,7 +555,7 @@ public function xmlCaseRoleDataProvider() {
   /**
    * Test XMLProcessor activityTypes()
    */
-  public function testXmlProcessorActivityTypes() {
+  public function testXmlProcessorActivityTypes(): void {
     // First change an activity's label since we also test getting the labels.
     // @todo Having a brain freeze or something - can't do this in one step?
     $activity_type_id = $this->callApiSuccess('OptionValue', 'get', [
diff --git a/tests/phpunit/CRM/Case/XMLProcessor/ReportTest.php b/tests/phpunit/CRM/Case/XMLProcessor/ReportTest.php
index 5ed613556fa8..1c99e40ba7b6 100644
--- a/tests/phpunit/CRM/Case/XMLProcessor/ReportTest.php
+++ b/tests/phpunit/CRM/Case/XMLProcessor/ReportTest.php
@@ -80,7 +80,7 @@ public function testGetCaseReport($activitySetName, $expected) {
    * This is similar to testGetCaseReport but test with a timeline that
    * does have Meeting in it.
    */
-  public function testGetCaseReportWithMeetingInTimeline() {
+  public function testGetCaseReportWithMeetingInTimeline(): void {
     $client_id = $this->individualCreate([
       'first_name' => 'Casey',
       'middle_name' => '',
diff --git a/tests/phpunit/CRM/Case/XMLProcessorTest.php b/tests/phpunit/CRM/Case/XMLProcessorTest.php
index 0150f7eda2ab..54b98060537c 100644
--- a/tests/phpunit/CRM/Case/XMLProcessorTest.php
+++ b/tests/phpunit/CRM/Case/XMLProcessorTest.php
@@ -22,7 +22,7 @@ public function setUp(): void {
    * Test that allRelationshipTypes() doesn't have name and label mixed up
    * and that is has the right directions.
    */
-  public function testAllRelationshipTypes() {
+  public function testAllRelationshipTypes(): void {
 
     // Add a relationship type to test against.
     $params = [
diff --git a/tests/phpunit/CRM/Case/XMLRepositoryTest.php b/tests/phpunit/CRM/Case/XMLRepositoryTest.php
index 9cf37e091e84..dc3e73a1c160 100644
--- a/tests/phpunit/CRM/Case/XMLRepositoryTest.php
+++ b/tests/phpunit/CRM/Case/XMLRepositoryTest.php
@@ -96,7 +96,7 @@ protected function setUp(): void {
 
   }
 
-  public function testGetAllDeclaredActivityTypes() {
+  public function testGetAllDeclaredActivityTypes(): void {
     $repo = new CRM_Case_XMLRepository(
       ['CaseTypeWithTwoActivityTypes', 'CaseTypeWithThreeActivityTypes'],
       [
@@ -113,7 +113,7 @@ public function testGetAllDeclaredActivityTypes() {
     $this->assertEquals($expected, $actual);
   }
 
-  public function testGetAllDeclaredRelationshipTypes() {
+  public function testGetAllDeclaredRelationshipTypes(): void {
     $repo = new CRM_Case_XMLRepository(
       ['CaseTypeWithTwoRoles', 'CaseTypeWithThreeRoles', 'CaseTypeWithSingleActivityType'],
       [
@@ -129,7 +129,7 @@ public function testGetAllDeclaredRelationshipTypes() {
     $this->assertEquals($expected, $actual);
   }
 
-  public function testGetActivityReferenceCount_1() {
+  public function testGetActivityReferenceCount_1(): void {
     $repo = new CRM_Case_XMLRepository(
       ['CaseTypeWithSingleActivityType'],
       [
@@ -145,7 +145,7 @@ public function testGetActivityReferenceCount_1() {
     $this->assertEquals(0, $repo->getActivityReferenceCount('Third Activity Type'));
   }
 
-  public function testGetActivityReferenceCount_23() {
+  public function testGetActivityReferenceCount_23(): void {
     $repo = new CRM_Case_XMLRepository(
       ['CaseTypeWithTwoActivityTypes', 'CaseTypeWithThreeActivityTypes'],
       [
@@ -162,7 +162,7 @@ public function testGetActivityReferenceCount_23() {
     $this->assertEquals(1, $repo->getActivityReferenceCount('Third Activity Type'));
   }
 
-  public function testGetRoleReferenceCount_1() {
+  public function testGetRoleReferenceCount_1(): void {
     $repo = new CRM_Case_XMLRepository(
       ['CaseTypeWithSingleRole', 'CaseTypeWithSingleActivityType'],
       [
@@ -178,7 +178,7 @@ public function testGetRoleReferenceCount_1() {
     $this->assertEquals(0, $repo->getRelationshipReferenceCount('Third Role'));
   }
 
-  public function testGetRoleReferenceCount_23() {
+  public function testGetRoleReferenceCount_23(): void {
     $repo = new CRM_Case_XMLRepository(
       ['CaseTypeWithTwoRoles', 'CaseTypeWithThreeRoles', 'CaseTypeWithSingleActivityType'],
       [
diff --git a/tests/phpunit/CRM/Contact/BAO/ContactTest.php b/tests/phpunit/CRM/Contact/BAO/ContactTest.php
index d323b5c7bebe..7dfd6ddfbd6b 100644
--- a/tests/phpunit/CRM/Contact/BAO/ContactTest.php
+++ b/tests/phpunit/CRM/Contact/BAO/ContactTest.php
@@ -456,7 +456,7 @@ public function testCreateWithAll(): void {
    *
    * Test all pseudoConstant, stateProvince, country.
    */
-  public function testResolveDefaults() {
+  public function testResolveDefaults(): void {
     $params = [];
 
     $params['address'][1] = [
@@ -1033,7 +1033,7 @@ public function testCreateProfileContact(): void {
   /**
    * Test case for getContactDetails( ).
    */
-  public function testGetContactDetails() {
+  public function testGetContactDetails(): void {
     //get the contact params
     $params = $this->contactParams();
 
@@ -1147,7 +1147,7 @@ public function testGetContactType(): void {
   /**
    * Test case for displayName( ).
    */
-  public function testDisplayName() {
+  public function testDisplayName(): void {
     //get the contact params
     $params = $this->contactParams();
 
@@ -1174,7 +1174,7 @@ public function testDisplayName() {
   /**
    * Test case for getDisplayAndImage( ).
    */
-  public function testGetDisplayAndImage() {
+  public function testGetDisplayAndImage(): void {
     //get the contact params
     $params = $this->contactParams();
 
@@ -1347,7 +1347,7 @@ public function testTimestampsEmail(): void {
   /**
    * Ensure that civicrm_contact.modified_date is updated when manipulating an email.
    */
-  public function testTimestampsPhone() {
+  public function testTimestampsPhone(): void {
     $test = $this;
     $this->_testTimestamps([
       'INSERT' => function ($contactId) use ($test) {
diff --git a/tests/phpunit/CRM/Contact/BAO/ContactType/ContactSearchTest.php b/tests/phpunit/CRM/Contact/BAO/ContactType/ContactSearchTest.php
index a68928fcda0e..a3d20fc598df 100644
--- a/tests/phpunit/CRM/Contact/BAO/ContactType/ContactSearchTest.php
+++ b/tests/phpunit/CRM/Contact/BAO/ContactType/ContactSearchTest.php
@@ -164,7 +164,7 @@ public function setUp(): void {
    *
    * Success expected.
    */
-  public function testSearchWithType() {
+  public function testSearchWithType(): void {
 
     // for type:Individual
     $params = ['contact_type' => 'Individual', 'version' => 3];
@@ -229,7 +229,7 @@ public function testSearchWithType() {
    *
    * Success expected.
    */
-  public function testSearchWithSubype() {
+  public function testSearchWithSubype(): void {
 
     // for subtype:Student
     $params = ['contact_sub_type' => $this->student, 'version' => 3];
@@ -277,7 +277,7 @@ public function testSearchWithSubype() {
    *
    * Success expected.
    */
-  public function testSearchWithTypeSubype() {
+  public function testSearchWithTypeSubype(): void {
 
     // for type:individual subtype:Student
     $params = ['contact_sub_type' => $this->student, 'version' => 3];
diff --git a/tests/phpunit/CRM/Contact/BAO/ContactType/ContactTest.php b/tests/phpunit/CRM/Contact/BAO/ContactType/ContactTest.php
index 4fcbc02c6415..73ae55ce5221 100644
--- a/tests/phpunit/CRM/Contact/BAO/ContactType/ContactTest.php
+++ b/tests/phpunit/CRM/Contact/BAO/ContactType/ContactTest.php
@@ -84,7 +84,7 @@ public function tearDown(): void {
    *
    * Success expected
    */
-  public function testCreateContact() {
+  public function testCreateContact(): void {
     //check for Type:Individual
     $params = [
       'first_name' => 'Anne',
@@ -167,7 +167,7 @@ public function testCreateContact() {
    *
    * Success expected.
    */
-  public function testUpdateContactNoSubtypeToValid() {
+  public function testUpdateContactNoSubtypeToValid(): void {
     $params = [
       'first_name' => 'Anne',
       'last_name' => 'Grant',
@@ -223,7 +223,7 @@ public function testUpdateContactNoSubtypeToValid() {
    * Update the contact with subtype to another valid subtype.
    * success expected
    */
-  public function testUpdateContactSubtype() {
+  public function testUpdateContactSubtype(): void {
     $params = [
       'first_name' => 'Anne',
       'last_name' => 'Grant',
@@ -313,7 +313,7 @@ public function testUpdateContactSubtype() {
    *
    * Success expected
    */
-  public function testCRM19133() {
+  public function testCRM19133(): void {
     $subtypesToPreserve = [$this->student, $this->parent];
 
     // Create custom group that extends student and parent subtype
diff --git a/tests/phpunit/CRM/Contact/BAO/ContactType/ContactTypeTest.php b/tests/phpunit/CRM/Contact/BAO/ContactType/ContactTypeTest.php
index f7079061ce78..68860ab33b56 100644
--- a/tests/phpunit/CRM/Contact/BAO/ContactType/ContactTypeTest.php
+++ b/tests/phpunit/CRM/Contact/BAO/ContactType/ContactTypeTest.php
@@ -59,7 +59,7 @@ public function tearDown(): void {
   /**
    * Test contactTypes() and subTypes() methods return correct contact types.
    */
-  public function testGetMethods() {
+  public function testGetMethods(): void {
     $result = CRM_Contact_BAO_ContactType::contactTypes(TRUE);
     $this->assertEquals(array_keys($this->getExpectedContactTypes()), $result);
 
@@ -89,7 +89,7 @@ public function testGetMethods() {
   /**
    * Test subTypes() methods with invalid data
    */
-  public function testGetMethodsInvalid() {
+  public function testGetMethodsInvalid(): void {
 
     $params = 'invalid';
     $result = CRM_Contact_BAO_ContactType::subTypes($params);
@@ -105,7 +105,7 @@ public function testGetMethodsInvalid() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testContactTypeInfo() {
+  public function testContactTypeInfo(): void {
     $blahType = ['is_active' => 0, 'name' => 'blah', 'label' => 'blah blah', 'parent_id:name' => 'Individual', 'icon' => 'fa-random'];
     $createdType = ContactType::create()->setValues($blahType)->execute()->first();
     $activeTypes = CRM_Contact_BAO_ContactType::contactTypeInfo();
@@ -340,7 +340,7 @@ public function getExpectedContactSubTypes($parentType) {
    * Test add() methods with valid data
    * success expected
    */
-  public function testAdd() {
+  public function testAdd(): void {
 
     $params = [
       'label' => 'indiviSubType',
@@ -372,7 +372,7 @@ public function testAdd() {
   /**
    * Test del() with valid data.
    */
-  public function testDel() {
+  public function testDel(): void {
 
     $params = [
       'label' => 'indiviSubType',
diff --git a/tests/phpunit/CRM/Contact/BAO/ContactType/RelationshipTest.php b/tests/phpunit/CRM/Contact/BAO/ContactType/RelationshipTest.php
index 178ee91bada6..bccc0b29082b 100644
--- a/tests/phpunit/CRM/Contact/BAO/ContactType/RelationshipTest.php
+++ b/tests/phpunit/CRM/Contact/BAO/ContactType/RelationshipTest.php
@@ -111,7 +111,7 @@ public function tearDown(): void {
    * Methods create relationshipType with valid data.
    * success expected
    */
-  public function testRelationshipTypeAddIndiviParent() {
+  public function testRelationshipTypeAddIndiviParent(): void {
     //check Individual to Parent RelationshipType
     $params = [
       'name_a_b' => 'indivToparent',
@@ -128,7 +128,7 @@ public function testRelationshipTypeAddIndiviParent() {
     $this->relationshipTypeDelete($result->id);
   }
 
-  public function testRelationshipTypeAddSponcorIndivi() {
+  public function testRelationshipTypeAddSponcorIndivi(): void {
     //check Sponcor to Individual RelationshipType
     $params = [
       'name_a_b' => 'SponsorToIndiv',
@@ -145,7 +145,7 @@ public function testRelationshipTypeAddSponcorIndivi() {
     $this->relationshipTypeDelete($result->id);
   }
 
-  public function testRelationshipTypeAddStudentSponcor() {
+  public function testRelationshipTypeAddStudentSponcor(): void {
     //check Student to Sponcer RelationshipType
     $params = [
       'name_a_b' => 'StudentToSponser',
@@ -164,7 +164,7 @@ public function testRelationshipTypeAddStudentSponcor() {
     $this->relationshipTypeDelete($result->id);
   }
 
-  public function testGetAnyToAnyRelTypes() {
+  public function testGetAnyToAnyRelTypes(): void {
     // Create an any to any relationship.
     $relTypeParams = [
       'name_a_b' => 'MookieIs',
diff --git a/tests/phpunit/CRM/Contact/BAO/GroupContactTest.php b/tests/phpunit/CRM/Contact/BAO/GroupContactTest.php
index 4587bc7e6430..05016a3df575 100644
--- a/tests/phpunit/CRM/Contact/BAO/GroupContactTest.php
+++ b/tests/phpunit/CRM/Contact/BAO/GroupContactTest.php
@@ -20,7 +20,7 @@ class CRM_Contact_BAO_GroupContactTest extends CiviUnitTestCase {
   /**
    * Test case for add( ).
    */
-  public function testAdd() {
+  public function testAdd(): void {
 
     //creates a test group contact by recursively creation
     //lets create 10 groupContacts for fun
@@ -40,7 +40,7 @@ public function testAdd() {
   /**
    * Test case for getGroupId( )
    */
-  public function testGetGroupId() {
+  public function testGetGroupId(): void {
 
     //creates a test groupContact object
     //force group_id to 1 so we can compare
@@ -62,7 +62,7 @@ public function testGetGroupId() {
    *
    * @throws \Exception
    */
-  public function testContactSearchByParentGroup() {
+  public function testContactSearchByParentGroup(): void {
     // create a parent group
     $parentGroup = $this->callAPISuccess('Group', 'create', [
       'title' => 'Parent Group',
@@ -160,7 +160,7 @@ public function testContactSearchByParentGroup() {
   /**
    *  CRM-19698: Test case for combine contact search in regular and smart group
    */
-  public function testContactCombineGroupSearch() {
+  public function testContactCombineGroupSearch(): void {
     // create regular group based
     $regularGroup = $this->callAPISuccess('Group', 'create', [
       'title' => 'Regular Group',
@@ -236,7 +236,7 @@ public function testContactCombineGroupSearch() {
   /**
    *  CRM-19333: Test case for contact search on basis of group type
    */
-  public function testbyGroupType() {
+  public function testbyGroupType(): void {
     $groupTypes = CRM_Core_BAO_OptionValue::getOptionValuesAssocArrayFromName('group_type');
     $mailingListGT = array_search('Mailing List', $groupTypes);
     $accessControlGT = array_search('Access Control', $groupTypes);
diff --git a/tests/phpunit/CRM/Contact/BAO/GroupTest.php b/tests/phpunit/CRM/Contact/BAO/GroupTest.php
index ddde07352d2f..f8924b0848c0 100644
--- a/tests/phpunit/CRM/Contact/BAO/GroupTest.php
+++ b/tests/phpunit/CRM/Contact/BAO/GroupTest.php
@@ -33,7 +33,7 @@ protected function tearDown(): void {
   /**
    * Test case for add( ).
    */
-  public function testAddSimple() {
+  public function testAddSimple(): void {
 
     $checkParams = $params = [
       'title' => 'Group Uno',
@@ -247,7 +247,7 @@ public function loadSavedSearches() {
    *  Copy the output to a single sql file and place in the SavedSearchDataSets folder - use the group number as the prefix.
    *  Try to keep as much of the real world irregular glory as you can! Don't change the table ids to be number 1 as this can hide errors
    */
-  public function testGroupData() {
+  public function testGroupData(): void {
     $groups = $this->dataProviderSavedSearch();
     foreach ($groups[0] as $groupID) {
       $group = new CRM_Contact_BAO_Group();
@@ -261,7 +261,7 @@ public function testGroupData() {
   /**
    * Ensure that when updating a group with a linked organisation record even tho that record's id doesn't match the group id no db error is produced
    */
-  public function testGroupUpdateWithOrganization() {
+  public function testGroupUpdateWithOrganization(): void {
     $params = [
       'name' => uniqid(),
       'title' => 'Group A',
@@ -299,7 +299,7 @@ public function testGroupUpdateWithOrganization() {
   /**
    * Ensure that when hidden smart group is created, wildcard string value is not ignored
    */
-  public function testHiddenSmartGroup() {
+  public function testHiddenSmartGroup(): void {
     $customGroup = $this->customGroupCreate();
     $fields = [
       'label' => 'testFld',
@@ -337,7 +337,7 @@ public function testHiddenSmartGroup() {
    * Test updating a group with just description and check the recent items
    * list has the right title.
    */
-  public function testGroupUpdateDescription() {
+  public function testGroupUpdateDescription(): void {
     // Create a group. Copied from $this->testAddSimple().
     // Note we need $checkParams because the function call changes $params.
     $checkParams = $params = [
diff --git a/tests/phpunit/CRM/Contact/BAO/IndividualTest.php b/tests/phpunit/CRM/Contact/BAO/IndividualTest.php
index 0307ef139076..e9e505ed4858 100644
--- a/tests/phpunit/CRM/Contact/BAO/IndividualTest.php
+++ b/tests/phpunit/CRM/Contact/BAO/IndividualTest.php
@@ -11,7 +11,7 @@ class CRM_Contact_BAO_IndividualTest extends CiviUnitTestCase {
    *
    * See CRM-19123: Merging contacts: blank date fields write as 1970
    */
-  public function testFormatNullDates() {
+  public function testFormatNullDates(): void {
     $params = [
       'contact_type' => 'Individual',
       'birth_date' => 'null',
@@ -29,7 +29,7 @@ public function testFormatNullDates() {
    *  Test case to check the formatting of the Display name and Sort name
    *  Standard formatting is assumed.
    */
-  public function testFormatDisplayName() {
+  public function testFormatDisplayName(): void {
 
     $params = [
       'contact_type' => 'Individual',
@@ -52,7 +52,7 @@ public function testFormatDisplayName() {
    *  Standard Prefixes and Suffixes are assumed part of
    *  the test database
    */
-  public function testFormatDisplayNamePrefixesById() {
+  public function testFormatDisplayNamePrefixesById(): void {
 
     $params = [
       'contact_type' => 'Individual',
@@ -76,7 +76,7 @@ public function testFormatDisplayNamePrefixesById() {
    *  Standard Prefixes and Suffixes are assumed part of
    *  the test database
    */
-  public function testFormatDisplayNameNoIndividual() {
+  public function testFormatDisplayNameNoIndividual(): void {
 
     $params = [
       'contact_type' => 'Organization',
@@ -94,7 +94,7 @@ public function testFormatDisplayNameNoIndividual() {
   /**
    *  When no first name or last name are defined, the primary email is used
    */
-  public function testFormatDisplayNameOnlyEmail() {
+  public function testFormatDisplayNameOnlyEmail(): void {
 
     $email['1'] = ['email' => "bleu01@example.com"];
     $email['2'] = ['email' => "bleu02@example.com", 'is_primary' => 1];
diff --git a/tests/phpunit/CRM/Contact/BAO/QueryStateNameTest.php b/tests/phpunit/CRM/Contact/BAO/QueryStateNameTest.php
index 65e75f5f917f..7361ad9bb1e1 100644
--- a/tests/phpunit/CRM/Contact/BAO/QueryStateNameTest.php
+++ b/tests/phpunit/CRM/Contact/BAO/QueryStateNameTest.php
@@ -12,7 +12,7 @@ class CRM_Contact_BAO_QueryStateNameTest extends CiviUnitTestCase {
    * See CRM-15505: Mailing labels show the state/province name as the abbreviation rather than the full state/province name
    * Change to CRM_Contact_BAO_query::convertToPseudoNames()
    */
-  public function testStateName() {
+  public function testStateName(): void {
     $state_name = 'Norfolk';
     $state_abbreviation = 'NFK';
     $create_params = [
diff --git a/tests/phpunit/CRM/Contact/BAO/QueryTest.php b/tests/phpunit/CRM/Contact/BAO/QueryTest.php
index 3dede9dc3102..a7c3835394b0 100644
--- a/tests/phpunit/CRM/Contact/BAO/QueryTest.php
+++ b/tests/phpunit/CRM/Contact/BAO/QueryTest.php
@@ -433,7 +433,7 @@ public function testSearchProfileHomeCityNoResultsCRM14263(): void {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testSearchPrimaryLocTypes() {
+  public function testSearchPrimaryLocTypes(): void {
     $contactID = $this->individualCreate();
     $params = [
       'contact_id' => $contactID,
@@ -489,7 +489,7 @@ public function testSearchPrimaryLocTypes() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testSearchOtherLocationUpperLower() {
+  public function testSearchOtherLocationUpperLower(): void {
 
     $params = [
       0 => [
@@ -596,7 +596,7 @@ public function getSearchProfileData() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testSearchBuilderActivityType() {
+  public function testSearchBuilderActivityType(): void {
     $queryObj = new CRM_Contact_BAO_Query([['activity_type', '=', '3', 1, 0]]);
     $this->assertStringContainsString('WHERE  (  ( civicrm_activity.activity_type_id = 3 )', $queryObj->getSearchSQL());
     $this->assertEquals('Activity Type = Email', $queryObj->_qill[1][0]);
@@ -642,7 +642,7 @@ public function testSearchBuilderActivityType() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testGroupContactCacheAddSearch() {
+  public function testGroupContactCacheAddSearch(): void {
     $returnProperties = ['contact_id'];
     $params = [['group', 'IN', [1], 0, 0]];
 
@@ -664,7 +664,7 @@ public function testGroupContactCacheAddSearch() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testNumericPostal() {
+  public function testNumericPostal(): void {
     // Precaution as hitting some inconsistent set up running in isolation vs in the suite.
     CRM_Core_DAO::executeQuery('UPDATE civicrm_address SET postal_code = NULL');
 
@@ -704,7 +704,7 @@ public function testNumericPostal() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testCaseInsensitive() {
+  public function testCaseInsensitive(): void {
     $orgID = $this->organizationCreate(['organization_name' => 'BOb']);
     $params = [
       'display_name' => 'Minnie Mouse',
@@ -739,7 +739,7 @@ public function testCaseInsensitive() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testNonNumericEqualsPostal() {
+  public function testNonNumericEqualsPostal(): void {
     $this->individualCreate(['api.address.create' => ['postal_code' => 5, 'location_type_id' => 'Main']]);
     $this->individualCreate(['api.address.create' => ['postal_code' => 'EH10 4RB-889', 'location_type_id' => 'Main']]);
     $this->individualCreate(['api.address.create' => ['postal_code' => '4', 'location_type_id' => 'Main']]);
@@ -767,7 +767,7 @@ public function testNonNumericEqualsPostal() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testRelationshipDescription() {
+  public function testRelationshipDescription(): void {
     $relType = $this->callAPISuccess('RelationshipType', 'create', [
       'name_a_b' => 'blah',
       'name_b_a' => 'other blah',
@@ -810,7 +810,7 @@ public function testRelationshipDescription() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testNonReciprocalRelationshipTargetGroupIsCorrectResults() {
+  public function testNonReciprocalRelationshipTargetGroupIsCorrectResults(): void {
     $contactID_a = $this->individualCreate();
     $contactID_b = $this->individualCreate();
     $this->callAPISuccess('Relationship', 'create', [
@@ -862,7 +862,7 @@ public function testNonReciprocalRelationshipTargetGroupIsCorrectResults() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testReciprocalRelationshipWithCustomFields() {
+  public function testReciprocalRelationshipWithCustomFields(): void {
     $params = [
       'extends' => 'Relationship',
     ];
@@ -910,7 +910,7 @@ public function testReciprocalRelationshipWithCustomFields() {
   /**
    * @throws \CRM_Core_Exception
    */
-  public function testReciprocalRelationshipTargetGroupIsCorrectResults() {
+  public function testReciprocalRelationshipTargetGroupIsCorrectResults(): void {
     $contactID_a = $this->individualCreate();
     $contactID_b = $this->individualCreate();
     $this->callAPISuccess('Relationship', 'create', [
@@ -962,7 +962,7 @@ public function testReciprocalRelationshipTargetGroupIsCorrectResults() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testReciprocalRelationshipTargetGroupUsesTempTable() {
+  public function testReciprocalRelationshipTargetGroupUsesTempTable(): void {
     $groupID = $this->groupCreate();
     $params = [
       [
@@ -995,7 +995,7 @@ public function testReciprocalRelationshipTargetGroupUsesTempTable() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testRelationshipPermissionClause() {
+  public function testRelationshipPermissionClause(): void {
     $params = [['relation_type_id', 'IN', ['1_b_a'], 0, 0], ['relation_permission', 'IN', [2], 0, 0]];
     $sql = CRM_Contact_BAO_Query::getQuery($params);
     $this->assertStringContainsString('(civicrm_relationship.is_permission_a_b IN (2))', $sql);
@@ -1006,7 +1006,7 @@ public function testRelationshipPermissionClause() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testRelationshipClause() {
+  public function testRelationshipClause(): void {
     $today = date('Ymd');
     $from1 = ' FROM civicrm_contact contact_a LEFT JOIN civicrm_relationship ON (civicrm_relationship.contact_id_a = contact_a.id ) LEFT JOIN civicrm_contact contact_b ON (civicrm_relationship.contact_id_b = contact_b.id )';
     $from2 = ' FROM civicrm_contact contact_a LEFT JOIN civicrm_relationship ON (civicrm_relationship.contact_id_b = contact_a.id ) LEFT JOIN civicrm_contact contact_b ON (civicrm_relationship.contact_id_a = contact_b.id )';
@@ -1083,7 +1083,7 @@ public function testRelationshipClause() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testGetByGroupWithStatus() {
+  public function testGetByGroupWithStatus(): void {
     $groupID = $this->groupCreate();
     $this->groupContactCreate($groupID, 3);
     $groupContactID = $this->callAPISuccessGetSingle('GroupContact', ['group_id' => $groupID, 'options' => ['limit' => 1]])['id'];
@@ -1106,7 +1106,7 @@ public function testGetByGroupWithStatus() {
    *
    * @throws \Exception
    */
-  public function testGetByGroupWithStatusSmartGroup() {
+  public function testGetByGroupWithStatusSmartGroup(): void {
     $groupID = $this->smartGroupCreate();
     // This means they are actually all hard-added, which is fine for this purpose.
     $this->groupContactCreate($groupID, 3);
@@ -1131,7 +1131,7 @@ public function testGetByGroupWithStatusSmartGroup() {
    *
    * @throws \Exception
    */
-  public function testGroupClause() {
+  public function testGroupClause(): void {
     $this->householdCreate();
     $householdID = $this->householdCreate();
     $individualID = $this->individualCreate();
@@ -1421,7 +1421,7 @@ protected function createContributionsForSummaryQueryTests(): void {
   /**
    * Test the options are handled for the qill.
    */
-  public function testQillOptions() {
+  public function testQillOptions(): void {
     $qill = CRM_Contact_BAO_Query::buildQillForFieldValue('CRM_Activity_BAO_Activity', 'activity_type_id', 2, '=');
     $this->assertEquals(['=', 'Phone Call'], $qill);
 
diff --git a/tests/phpunit/CRM/Contact/BAO/RelationshipCacheTest.php b/tests/phpunit/CRM/Contact/BAO/RelationshipCacheTest.php
index 006d39dfe5fa..a745a5473b59 100644
--- a/tests/phpunit/CRM/Contact/BAO/RelationshipCacheTest.php
+++ b/tests/phpunit/CRM/Contact/BAO/RelationshipCacheTest.php
@@ -26,7 +26,7 @@ protected function setUp(): void {
    * Whenever one `Relationship` is created, there should be two corresponding
    * `RelationshipCache` records.
    */
-  public function testRelationshipCache() {
+  public function testRelationshipCache(): void {
     // add a new type
     $relationship_type_id_1 = $this->relationshipTypeCreate([
       'name_a_b' => 'Praegustator is',
diff --git a/tests/phpunit/CRM/Contact/BAO/RelationshipTest.php b/tests/phpunit/CRM/Contact/BAO/RelationshipTest.php
index b8b03511f0a0..c690e25dffef 100644
--- a/tests/phpunit/CRM/Contact/BAO/RelationshipTest.php
+++ b/tests/phpunit/CRM/Contact/BAO/RelationshipTest.php
@@ -41,7 +41,7 @@ protected function tearDown(): void {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testRelationshipTypeOptionsWillReturnSpecifiedType() {
+  public function testRelationshipTypeOptionsWillReturnSpecifiedType(): void {
     $orgToOrgType = 'A_B_relationship';
     $orgToOrgReverseType = 'B_A_relationship';
     $this->callAPISuccess('RelationshipType', 'create', [
@@ -69,7 +69,7 @@ public function testRelationshipTypeOptionsWillReturnSpecifiedType() {
     $this->assertNotContains($orgToOrgReverseType, $result['values']);
   }
 
-  public function testContactIdAndRelationshipIdWillBeUsedInFilter() {
+  public function testContactIdAndRelationshipIdWillBeUsedInFilter(): void {
     $individual = civicrm_api3('Contact', 'create', [
       'display_name' => 'Individual A',
       'contact_type' => 'Individual',
@@ -203,7 +203,7 @@ public function getRelationshipTypeDuplicates() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testSingleMembershipForTwoRelationships() {
+  public function testSingleMembershipForTwoRelationships(): void {
     $individualID = $this->individualCreate(['display_name' => 'Individual A']);
     $organisationID = $this->organizationCreate(['organization_name' => 'Organization B']);
     $membershipOrganisationID = $this->organizationCreate(['organization_name' => 'Membership Organization']);
@@ -283,7 +283,7 @@ public function testSingleMembershipForTwoRelationships() {
    * for the api, but since it does some more business logic after too the
    * tests might not be checking exactly the same thing.
    */
-  public function testBAOAdd() {
+  public function testBAOAdd(): void {
     // add a new type
     $relationship_type_id_1 = $this->relationshipTypeCreate([
       'name_a_b' => 'Food poison tester is',
@@ -329,7 +329,7 @@ public function testBAOAdd() {
    * @return void
    * @throws \CRM_Core_Exception
    */
-  public function testDisableInvalidRelationship() {
+  public function testDisableInvalidRelationship(): void {
     $individualStaff = civicrm_api3('Contact', 'create', [
       'display_name' => 'Individual A',
       'contact_type' => 'Individual',
diff --git a/tests/phpunit/CRM/Contact/BAO/SavedSearchTest.php b/tests/phpunit/CRM/Contact/BAO/SavedSearchTest.php
index bfce41175f77..5df4afea73d5 100644
--- a/tests/phpunit/CRM/Contact/BAO/SavedSearchTest.php
+++ b/tests/phpunit/CRM/Contact/BAO/SavedSearchTest.php
@@ -48,7 +48,7 @@ protected function tearDown(): void {
    *
    * @throws \Exception
    */
-  public function testDefaultValues() {
+  public function testDefaultValues(): void {
     $this->createCustomGroupWithFieldOfType([], 'int');
     $sg = new CRM_Contact_Form_Search_Advanced();
     $sg->controller = new CRM_Core_Controller();
@@ -83,7 +83,7 @@ public function testDefaultValues() {
    *
    * @throws \Exception
    */
-  public function testGetFormValuesWithCustomFields() {
+  public function testGetFormValuesWithCustomFields(): void {
     $this->createCustomGroupWithFieldsOfAllTypes();
     $sg = new CRM_Contact_Form_Search_Advanced();
     $sg->controller = new CRM_Core_Controller();
@@ -127,7 +127,7 @@ public function testGetFormValues($formValues, $expectedResult, $searchDescripti
    * Test if skipped elements are correctly
    * stored and retrieved as formvalues.
    */
-  public function testSkippedElements() {
+  public function testSkippedElements(): void {
     $relTypeID = $this->relationshipTypeCreate();
     $savedSearch = new CRM_Contact_BAO_SavedSearch();
     $formValues = [
diff --git a/tests/phpunit/CRM/Contact/Form/Search/SearchContactTest.php b/tests/phpunit/CRM/Contact/Form/Search/SearchContactTest.php
index fcbb20f3adce..9e992a34295b 100644
--- a/tests/phpunit/CRM/Contact/Form/Search/SearchContactTest.php
+++ b/tests/phpunit/CRM/Contact/Form/Search/SearchContactTest.php
@@ -22,7 +22,7 @@ class CRM_Contact_Form_Search_SearchContactTest extends CiviUnitTestCase {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testContactSubtype() {
+  public function testContactSubtype(): void {
     foreach (['Contact_sub_type', 'Contact2__sub__type'] as $contactSubType) {
       $subType = $this->callAPISuccess('ContactType', 'create', [
         'name' => $contactSubType,
@@ -88,7 +88,7 @@ protected function searchContacts($contactSubType) {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testContactSearchOnGroupType() {
+  public function testContactSearchOnGroupType(): void {
     $groupTypes = $this->callAPISuccess('OptionValue', 'get', [
       'return' => ['id', 'name'],
       'option_group_id' => 'group_type',
diff --git a/tests/phpunit/CRM/Contact/Form/Task/DeleteTest.php b/tests/phpunit/CRM/Contact/Form/Task/DeleteTest.php
index 07e48e9cf18f..bd28ad3ef863 100644
--- a/tests/phpunit/CRM/Contact/Form/Task/DeleteTest.php
+++ b/tests/phpunit/CRM/Contact/Form/Task/DeleteTest.php
@@ -41,7 +41,7 @@ protected function tearDown(): void {
   /**
    * Test delete to trash.
    */
-  public function testDeleteToTrash() {
+  public function testDeleteToTrash(): void {
     $old_undelete_setting = Civi::settings()->get('contact_undelete');
     Civi::settings()->set('contact_undelete', '1');
 
@@ -66,7 +66,7 @@ public function testDeleteToTrash() {
   /**
    * Test restore from trash.
    */
-  public function testRestoreFromTrash() {
+  public function testRestoreFromTrash(): void {
     // First, put in trash.
     $this->testDeleteToTrash();
     // Clear session status
@@ -100,7 +100,7 @@ public function testRestoreFromTrash() {
    * This is different from testDeleteWithoutTrash. This is where you have
    * trash enabled and first move to trash, then delete from the trash.
    */
-  public function testDeletePermanently() {
+  public function testDeletePermanently(): void {
     // First, put in trash.
     $this->testDeleteToTrash();
     // Clear session status
@@ -134,7 +134,7 @@ public function testDeletePermanently() {
    * This is different from testDeletePermanently. This is where trash is
    * not enabled at all.
    */
-  public function testDeleteWithoutTrash() {
+  public function testDeleteWithoutTrash(): void {
     $old_undelete_setting = Civi::settings()->get('contact_undelete');
     Civi::settings()->set('contact_undelete', '0');
 
diff --git a/tests/phpunit/CRM/Contact/Form/Task/UseraddTest.php b/tests/phpunit/CRM/Contact/Form/Task/UseraddTest.php
index 714a228ebf98..18b606e44dd1 100644
--- a/tests/phpunit/CRM/Contact/Form/Task/UseraddTest.php
+++ b/tests/phpunit/CRM/Contact/Form/Task/UseraddTest.php
@@ -20,7 +20,7 @@ class CRM_Contact_Form_Task_UseraddTest extends CiviUnitTestCase {
    * In unit tests, the CMS user creation will always fail, but that's
    * ok because that's what we're testing here.
    */
-  public function testUserCreateFail() {
+  public function testUserCreateFail(): void {
     $form = new CRM_Contact_Form_Task_Useradd();
     // We don't need to set params or anything because we're testing fail,
     // which the user creation will do in unit tests no matter what we set.
diff --git a/tests/phpunit/CRM/Contact/Page/AjaxTest.php b/tests/phpunit/CRM/Contact/Page/AjaxTest.php
index aec798dd940e..03569884b9bf 100644
--- a/tests/phpunit/CRM/Contact/Page/AjaxTest.php
+++ b/tests/phpunit/CRM/Contact/Page/AjaxTest.php
@@ -28,7 +28,7 @@ public function tearDown(): void {
   /**
    * Minimal test on the testGetDupes function to make sure it completes without error.
    */
-  public function testGetDedupes() {
+  public function testGetDedupes(): void {
     $_REQUEST['gid'] = 1;
     $_REQUEST['rgid'] = 1;
     $_REQUEST['columns'] = [
@@ -50,7 +50,7 @@ public function testGetDedupes() {
    *
    * @throws \Exception
    */
-  public function testProcessDupes() {
+  public function testProcessDupes(): void {
     $contact1 = $this->individualCreate();
     $contact2 = $this->individualCreate();
     $contact3 = $this->individualCreate();
@@ -61,7 +61,7 @@ public function testProcessDupes() {
     $this->callAPISuccessGetSingle('Exception', ['contact_id1' => $contact1, 'contact_id2' => $contact3]);
   }
 
-  public function testGetDedupesPostCode() {
+  public function testGetDedupesPostCode(): void {
     $_REQUEST['gid'] = 1;
     $_REQUEST['rgid'] = 1;
     $_REQUEST['snippet'] = 4;
@@ -242,7 +242,7 @@ public function testGetDedupesPostCode() {
   /**
    * CRM-20621 : Test to check usage count of Tag tree
    */
-  public function testGetTagTree() {
+  public function testGetTagTree(): void {
     $contacts = [];
     // create three contacts
     for ($i = 0; $i < 3; $i++) {
@@ -340,7 +340,7 @@ public function testGetTagTree() {
   /**
    * Test to check contact reference field
    */
-  public function testContactReference() {
+  public function testContactReference(): void {
     //create group
     $groupId1 = $this->groupCreate();
     $groupId2 = $this->groupCreate([
diff --git a/tests/phpunit/CRM/Contact/Page/DedupeExceptionTest.php b/tests/phpunit/CRM/Contact/Page/DedupeExceptionTest.php
index c660c05292d1..af0ec3aac059 100644
--- a/tests/phpunit/CRM/Contact/Page/DedupeExceptionTest.php
+++ b/tests/phpunit/CRM/Contact/Page/DedupeExceptionTest.php
@@ -17,7 +17,7 @@
  */
 class CRM_Contact_Page_DedupeExceptionTest extends CiviUnitTestCase {
 
-  public function testGetDedupeExceptions() {
+  public function testGetDedupeExceptions(): void {
     $contact1      = $this->individualCreate();
     $contact2      = $this->individualCreate();
     $exception     = $this->callAPISuccess('Exception', 'create', [
diff --git a/tests/phpunit/CRM/Contact/Page/View/UserDashboard/GroupContactTest.php b/tests/phpunit/CRM/Contact/Page/View/UserDashboard/GroupContactTest.php
index 2a0936eed1d4..7556abfb1d13 100644
--- a/tests/phpunit/CRM/Contact/Page/View/UserDashboard/GroupContactTest.php
+++ b/tests/phpunit/CRM/Contact/Page/View/UserDashboard/GroupContactTest.php
@@ -21,7 +21,7 @@ class CRM_Contact_Page_View_UserDashboard_GroupContactTest extends CiviUnitTestC
    * Test that the list of the contact's joined groups, on the Contact Dashboard,
    * contains the correct groups.
    */
-  public function testBrowseDisplaysCorrectListOfAddedGroups() {
+  public function testBrowseDisplaysCorrectListOfAddedGroups(): void {
     // create admin-only non-smart group
     $adminStdGroupTitle = 'The Admin-only Std Group';
     $adminStdGroup = $this->callAPISuccess('Group', 'create', [
@@ -96,7 +96,7 @@ public function testBrowseDisplaysCorrectListOfAddedGroups() {
    * Test that the select list of available groups, on the Contact Dashboard,
    * contains the correct groups.
    */
-  public function testBrowseDisplaysCorrectListOfAVailableGroups() {
+  public function testBrowseDisplaysCorrectListOfAVailableGroups(): void {
 
     // create admin-only non-smart group
     $adminStdGroupTitle = 'The Admin-only Std Group' . uniqid();
diff --git a/tests/phpunit/CRM/Contribute/BAO/ContributionTypeTest.php b/tests/phpunit/CRM/Contribute/BAO/ContributionTypeTest.php
index a14714659d35..470bcbb1f0a8 100644
--- a/tests/phpunit/CRM/Contribute/BAO/ContributionTypeTest.php
+++ b/tests/phpunit/CRM/Contribute/BAO/ContributionTypeTest.php
@@ -28,7 +28,7 @@ public function tearDown(): void {
   /**
    * Check method add()
    */
-  public function testAdd() {
+  public function testAdd(): void {
     $params = [
       'name' => 'Donations',
       'is_deductible' => 0,
diff --git a/tests/phpunit/CRM/Contribute/BAO/ProductTest.php b/tests/phpunit/CRM/Contribute/BAO/ProductTest.php
index b87dc2bffc97..4a84260672f7 100644
--- a/tests/phpunit/CRM/Contribute/BAO/ProductTest.php
+++ b/tests/phpunit/CRM/Contribute/BAO/ProductTest.php
@@ -18,7 +18,7 @@ class CRM_Contribute_BAO_ProductTest extends CiviUnitTestCase {
   /**
    * Check method add()
    */
-  public function testAdd() {
+  public function testAdd(): void {
     $params = [
       'name' => 'Test Product',
       'sku' => 'TP-10',
@@ -41,7 +41,7 @@ public function testAdd() {
   /**
    * Check method retrieve( )
    */
-  public function testRetrieve() {
+  public function testRetrieve(): void {
     $params = [
       'name' => 'Test Product',
       'sku' => 'TP-10',
@@ -62,7 +62,7 @@ public function testRetrieve() {
   /**
    * Check method del( )
    */
-  public function testDel() {
+  public function testDel(): void {
     $params = [
       'name' => 'Test Product',
       'sku' => 'TP-10',
diff --git a/tests/phpunit/CRM/Contribute/BAO/QueryTest.php b/tests/phpunit/CRM/Contribute/BAO/QueryTest.php
index 0c18acc6bed2..e5ea63dc7b80 100644
--- a/tests/phpunit/CRM/Contribute/BAO/QueryTest.php
+++ b/tests/phpunit/CRM/Contribute/BAO/QueryTest.php
@@ -73,7 +73,7 @@ public function getSortFields() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testRelativeContributionDates() {
+  public function testRelativeContributionDates(): void {
     $contribution1 = $this->contributionCreate(['receive_date' => '2018-01-02', 'contact_id' => $this->individualCreate()]);
     $contribution2 = $this->contributionCreate(['receive_date' => '2017-01-02', 'contact_id' => $this->individualCreate()]);
     $queryObj = new CRM_Contact_BAO_Query([['receive_date_low', '=', 20170101, 1, 0]]);
@@ -86,7 +86,7 @@ public function testRelativeContributionDates() {
     $this->callAPISuccess('Contribution', 'delete', ['id' => $contribution2]);
   }
 
-  public function testContributionWithoutSoftCredits() {
+  public function testContributionWithoutSoftCredits(): void {
     $contribution1 = $this->contributionCreate(['receive_date' => '2018-01-02', 'contact_id' => $this->individualCreate()]);
     $contact2 = $this->callAPISuccess('Contact', 'create', [
       'display_name' => 'superman',
diff --git a/tests/phpunit/CRM/Contribute/Form/ContributionPage/SettingsTest.php b/tests/phpunit/CRM/Contribute/Form/ContributionPage/SettingsTest.php
index 9e01fba3a47e..77c38f3007a1 100644
--- a/tests/phpunit/CRM/Contribute/Form/ContributionPage/SettingsTest.php
+++ b/tests/phpunit/CRM/Contribute/Form/ContributionPage/SettingsTest.php
@@ -19,7 +19,7 @@ private function getCorrectFormFields() {
   /**
    * Test correct form submission.
    */
-  public function testValidFormSubmission() {
+  public function testValidFormSubmission(): void {
     $values = $this->getCorrectFormFields();
     $form = new CRM_Contribute_Form_ContributionPage_Settings();
     $validationResult = \CRM_Contribute_Form_ContributionPage_Settings::formRule($values, [], $form);
@@ -29,7 +29,7 @@ public function testValidFormSubmission() {
   /**
    * Test end date not allowed with only 'time' part.
    */
-  public function testEndDateWithoutDateNotAllowed() {
+  public function testEndDateWithoutDateNotAllowed(): void {
     $values = $this->getCorrectFormFields();
     $values['end_date'] = '00:01';
     $form = new CRM_Contribute_Form_ContributionPage_Settings();
@@ -40,7 +40,7 @@ public function testEndDateWithoutDateNotAllowed() {
   /**
    * Test end date must be after start date.
    */
-  public function testEndDateBeforeStartDateNotAllowed() {
+  public function testEndDateBeforeStartDateNotAllowed(): void {
     $values = $this->getCorrectFormFields();
     $values['end_date'] = '1900-01-01 00:00';
     $form = new CRM_Contribute_Form_ContributionPage_Settings();
diff --git a/tests/phpunit/CRM/Contribute/Form/ContributionPageTranslationTest.php b/tests/phpunit/CRM/Contribute/Form/ContributionPageTranslationTest.php
index 76a0ac9fc34c..23598a53a829 100644
--- a/tests/phpunit/CRM/Contribute/Form/ContributionPageTranslationTest.php
+++ b/tests/phpunit/CRM/Contribute/Form/ContributionPageTranslationTest.php
@@ -33,7 +33,7 @@ public function tearDown(): void {
   /**
    * Create() method (create Contribution Page with Honor block)
    */
-  public function testCreateHonor() {
+  public function testCreateHonor(): void {
     CRM_Core_I18n::singleton()->setLocale('en_US');
 
     $params = [
diff --git a/tests/phpunit/CRM/Contribute/Form/ContributionTest.php b/tests/phpunit/CRM/Contribute/Form/ContributionTest.php
index 73139803598f..47f6cca67046 100644
--- a/tests/phpunit/CRM/Contribute/Form/ContributionTest.php
+++ b/tests/phpunit/CRM/Contribute/Form/ContributionTest.php
@@ -2048,7 +2048,7 @@ public function additionalInfoProvider(): array {
   /**
    * Test formRule
    */
-  public function testContributionFormRule() {
+  public function testContributionFormRule(): void {
     $fields = [
       'contact_id' => $this->_individualId,
       'financial_type_id' => CRM_Core_PseudoConstant::getKey('CRM_Contribute_BAO_Contribution', 'financial_type_id', 'Donation'),
diff --git a/tests/phpunit/CRM/Contribute/Form/ContributionViewTest.php b/tests/phpunit/CRM/Contribute/Form/ContributionViewTest.php
index d95c0e255f5b..a05f85830fcf 100644
--- a/tests/phpunit/CRM/Contribute/Form/ContributionViewTest.php
+++ b/tests/phpunit/CRM/Contribute/Form/ContributionViewTest.php
@@ -43,7 +43,7 @@ public function tearDown(): void {
   /**
    * Test that can still view a contribution without full permissions.
    */
-  public function testContributionViewLimitedPermissions() {
+  public function testContributionViewLimitedPermissions(): void {
     CRM_Core_Config::singleton()->userPermissionClass->permissions = [
       'access CiviCRM',
       'access all custom data',
@@ -75,7 +75,7 @@ public function testContributionViewLimitedPermissions() {
     $this->assertStringContainsString('Mr. Anthony Anderson II', $contents);
   }
 
-  public function testInvoiceDownload() {
+  public function testInvoiceDownload(): void {
     Civi::settings()->set('invoicing', 1);
 
     $_SERVER['REQUEST_URI'] = "civicrm/contribute/invoice?reset=1&id={$this->contribution['id']}&cid={$this->contact_id}";
diff --git a/tests/phpunit/CRM/Contribute/Form/SearchTest.php b/tests/phpunit/CRM/Contribute/Form/SearchTest.php
index 0d396b645b81..71b478f0ef9a 100644
--- a/tests/phpunit/CRM/Contribute/Form/SearchTest.php
+++ b/tests/phpunit/CRM/Contribute/Form/SearchTest.php
@@ -38,7 +38,7 @@ public function tearDown(): void {
   /**
    *  CRM-19325: Test CRM_Contribute_Form_Search batch filters
    */
-  public function testBatchFilter() {
+  public function testBatchFilter(): void {
     $this->quickCleanup($this->_tablesToTruncate);
     $contactID1 = $this->individualCreate([], 1);
     $contactID2 = $this->individualCreate([], 2);
@@ -155,7 +155,7 @@ public function testBatchFilter() {
   /**
    *  CRM-20286: Test CRM_Contribute_Form_Search Card type filters
    */
-  public function testCardTypeFilter() {
+  public function testCardTypeFilter(): void {
     $this->quickCleanup($this->_tablesToTruncate);
     $contactID1 = $this->individualCreate([], 1);
     $contactID2 = $this->individualCreate([], 2);
@@ -257,7 +257,7 @@ public function testCardTypeFilter() {
   /**
    *  CRM-20391: Test CRM_Contribute_Form_Search Card Number filters
    */
-  public function testCardNumberFilter() {
+  public function testCardNumberFilter(): void {
     $this->quickCleanup($this->_tablesToTruncate);
     $contactID1 = $this->individualCreate([], 1);
     $contactID2 = $this->individualCreate([], 2);
@@ -354,7 +354,7 @@ public function testCardNumberFilter() {
   /**
    *  Test contact contributions.
    */
-  public function testContributionSearchWithContactID() {
+  public function testContributionSearchWithContactID(): void {
     $contactID = $this->individualCreate([], 1);
     $fv = ['contact_id' => $contactID];
     $queryParams = CRM_Contact_BAO_Query::convertFormValues($fv);
@@ -415,7 +415,7 @@ public function testContributionRecurSearchFilters($formValues, $expectedCount,
    *
    * @throws CRM_Core_Exception
    */
-  public function testCancelledFilter() {
+  public function testCancelledFilter(): void {
     $this->quickCleanup($this->_tablesToTruncate);
     $contactID1 = $this->individualCreate([], 1);
     $contactID2 = $this->individualCreate([], 2);
diff --git a/tests/phpunit/CRM/Contribute/Form/Task/StatusTest.php b/tests/phpunit/CRM/Contribute/Form/Task/StatusTest.php
index 02b91f99955f..13ece874a009 100644
--- a/tests/phpunit/CRM/Contribute/Form/Task/StatusTest.php
+++ b/tests/phpunit/CRM/Contribute/Form/Task/StatusTest.php
@@ -79,7 +79,7 @@ public function testUpdatePendingContributionWithSendingEmail(): void {
   /**
    * Test update pending contribution without sending a confirmation mail.
    */
-  public function testUpdatePendingContributionWithoutSendingEmail() {
+  public function testUpdatePendingContributionWithoutSendingEmail(): void {
     $this->_individualId = $this->individualCreate();
     $form = new CRM_Contribute_Form_Task_Status();
 
diff --git a/tests/phpunit/CRM/Contribute/Form/UpdateSubscriptionTest.php b/tests/phpunit/CRM/Contribute/Form/UpdateSubscriptionTest.php
index 2199e7597513..d0d4e7ef9531 100644
--- a/tests/phpunit/CRM/Contribute/Form/UpdateSubscriptionTest.php
+++ b/tests/phpunit/CRM/Contribute/Form/UpdateSubscriptionTest.php
@@ -60,7 +60,7 @@ public function getExpectedMailStrings(): array {
   /**
    * Test the Additional Details pane loads for recurring contributions.
    */
-  public function testAdditionalDetails() {
+  public function testAdditionalDetails(): void {
     $this->addContribution();
     $templateContribution = CRM_Contribute_BAO_ContributionRecur::getTemplateContribution($this->getContributionRecurID());
     $_GET['q'] = $_REQUEST['q'] = 'civicrm/contact/view/contribution';
diff --git a/tests/phpunit/CRM/Contribute/PseudoConstantTest.php b/tests/phpunit/CRM/Contribute/PseudoConstantTest.php
index e7421c57b1d4..c12bd1980e8c 100644
--- a/tests/phpunit/CRM/Contribute/PseudoConstantTest.php
+++ b/tests/phpunit/CRM/Contribute/PseudoConstantTest.php
@@ -30,7 +30,7 @@ public function tearDown(): void {
    *
    * Future is CRM_Financial_BAO_FinancialAccount::getFinancialAccountForFinancialTypeByRelationship
    */
-  public function testGetRelationalFinancialAccount() {
+  public function testGetRelationalFinancialAccount(): void {
     $financialTypes = $this->callAPISuccess('FinancialType', 'get', [])['values'];
     $financialAccounts = $this->callAPISuccess('FinancialAccount', 'get', [])['values'];
     foreach ($financialTypes as $financialType) {
@@ -59,7 +59,7 @@ public function testGetRelationalFinancialAccount() {
    *
    * Future is CRM_Financial_BAO_FinancialAccount::getFinancialAccountForFinancialTypeByRelationship
    */
-  public function testGetRelationalFinancialAccountForPaymentInstrument() {
+  public function testGetRelationalFinancialAccountForPaymentInstrument(): void {
     $paymentInstruments = $this->callAPISuccess('Contribution', 'getoptions', ['field' => 'payment_instrument_id'])['values'];
     $financialAccounts = $this->callAPISuccess('FinancialAccount', 'get', [])['values'];
     foreach ($paymentInstruments as $paymentInstrumentID => $paymentInstrumentName) {
diff --git a/tests/phpunit/CRM/Contribute/Selector/SearchTest.php b/tests/phpunit/CRM/Contribute/Selector/SearchTest.php
index 66810c3d4447..8baaca5234c7 100644
--- a/tests/phpunit/CRM/Contribute/Selector/SearchTest.php
+++ b/tests/phpunit/CRM/Contribute/Selector/SearchTest.php
@@ -19,7 +19,7 @@ class CRM_Contribute_Selector_SearchTest extends CiviUnitTestCase {
   /**
    * CRM-20866 - Soft credit appearance inconsistent in contribution search
    */
-  public function testSoftCreditFieldsSelected() {
+  public function testSoftCreditFieldsSelected(): void {
     $queryParams = [['contribution_or_softcredits', '=', 'both_related', 0, 0]];
     $searchSelector = new CRM_Contribute_Selector_Search($queryParams, CRM_Core_Action::VIEW);
 
@@ -30,7 +30,7 @@ public function testSoftCreditFieldsSelected() {
   /**
    * CRM-20866 - Soft credit appearance inconsistent in contribution search
    */
-  public function testSoftCreditFieldNotSelected() {
+  public function testSoftCreditFieldNotSelected(): void {
     $queryParams = [['contribution_or_softcredits', '=', 'only_contribs', 0, 0]];
     $searchSelector = new CRM_Contribute_Selector_Search($queryParams, CRM_Core_Action::VIEW);
 
diff --git a/tests/phpunit/CRM/Core/BAO/AddressTest.php b/tests/phpunit/CRM/Core/BAO/AddressTest.php
index 5780a6c0a968..760f8ce00b95 100644
--- a/tests/phpunit/CRM/Core/BAO/AddressTest.php
+++ b/tests/phpunit/CRM/Core/BAO/AddressTest.php
@@ -27,7 +27,7 @@ public function setUp(): void {
   /**
    * Create() method (create and update modes)
    */
-  public function testCreate() {
+  public function testCreate(): void {
     $contactId = $this->individualCreate();
 
     $params = [];
@@ -91,7 +91,7 @@ public function testCreate() {
   /**
    * Add() method ( )
    */
-  public function testAdd() {
+  public function testAdd(): void {
     $contactId = $this->individualCreate();
 
     $fixParams = [
@@ -133,7 +133,7 @@ public function testAdd() {
    * Add 2 billing addresses using the `CRM_Core_BAO_Address::legacyCreate` mode
    * Only the first array will remain as primary/billing due to the nature of how `legacyCreate` works
    */
-  public function testMultipleBillingAddressesLegacymode() {
+  public function testMultipleBillingAddressesLegacymode(): void {
     $contactId = $this->individualCreate();
 
     $entityBlock = ['contact_id' => $contactId];
@@ -193,7 +193,7 @@ public function testMultipleBillingAddressesLegacymode() {
    * Using the `CRM_Core_BAO_Address::add` mode
    *
    */
-  public function testMultipleBillingAddressesCurrentmode() {
+  public function testMultipleBillingAddressesCurrentmode(): void {
     $contactId = $this->individualCreate();
 
     $entityBlock = ['contact_id' => $contactId];
@@ -263,7 +263,7 @@ public function testMultipleBillingAddressesCurrentmode() {
   /**
    * AllAddress() method ( )
    */
-  public function testallAddress() {
+  public function testallAddress(): void {
     $contactId = $this->individualCreate();
 
     $fixParams = [
@@ -325,7 +325,7 @@ public function testallAddress() {
   /**
    * AllAddress() method ( ) with null value
    */
-  public function testnullallAddress() {
+  public function testnullallAddress(): void {
     $contactId = $this->individualCreate();
 
     $fixParams = [
@@ -365,7 +365,7 @@ public function testnullallAddress() {
   /**
    * GetValues() method (get Address fields)
    */
-  public function testGetValues() {
+  public function testGetValues(): void {
     $contactId = $this->individualCreate();
 
     $params = [];
@@ -432,7 +432,7 @@ public function setStreetAddressParsing($status) {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testParseStreetAddressIfEnabled() {
+  public function testParseStreetAddressIfEnabled(): void {
     // Turn off address standardization. Parsing should work without it.
     Civi::settings()->set('address_standardization_provider', NULL);
 
@@ -464,7 +464,7 @@ public function testParseStreetAddressIfEnabled() {
   /**
    * ParseStreetAddress() method (get street address parsed)
    */
-  public function testParseStreetAddress() {
+  public function testParseStreetAddress(): void {
 
     // valid Street address to be parsed ( without locale )
     $street_address = "54A Excelsior Ave. Apt 1C";
@@ -580,7 +580,7 @@ public function sampleOFUnsupportedAddressParsingLocales() {
    * Address of Contact C should reflect contact A's address change
    * Also, Contact C's address' master_id should be Contact A's address id.
    */
-  public function testSharedAddressChaining1() {
+  public function testSharedAddressChaining1(): void {
     $contactIdA = $this->individualCreate([], 0);
     $contactIdB = $this->individualCreate([], 1);
     $contactIdC = $this->individualCreate([], 2);
@@ -640,7 +640,7 @@ public function testSharedAddressChaining1() {
    * Address of Contact C should reflect contact B's address change
    * Also, Contact C's address' master_id should be Contact B's address id.
    */
-  public function testSharedAddressChaining2() {
+  public function testSharedAddressChaining2(): void {
     $contactIdA = $this->individualCreate([], 0);
     $contactIdB = $this->individualCreate([], 1);
     $contactIdC = $this->individualCreate([], 2);
@@ -706,7 +706,7 @@ public function testSharedAddressChaining2() {
    * 3. Use contact A's address for contact A's address
    * An error should be given, and master_id should remain the same.
    */
-  public function testSharedAddressChaining3() {
+  public function testSharedAddressChaining3(): void {
     $contactIdA = $this->individualCreate([], 0);
 
     $addressParamsA = [
@@ -737,7 +737,7 @@ public function testSharedAddressChaining3() {
    * 1. test the creation of the shared address with custom field
    * 2. test the update of the custom field in the master
    */
-  public function testSharedAddressCustomField() {
+  public function testSharedAddressCustomField(): void {
 
     $this->createCustomGroupWithFieldOfType(['extends' => 'Address'], 'text');
     $customField = $this->getCustomFieldName('text');
@@ -784,7 +784,7 @@ public function testSharedAddressCustomField() {
   /**
    * Pinned countries with Default country
    */
-  public function testPinnedCountriesWithDefaultCountry() {
+  public function testPinnedCountriesWithDefaultCountry(): void {
     // Guyana, Netherlands, United States
     $pinnedCountries = ['1093', '1152', '1228'];
 
@@ -808,7 +808,7 @@ public function testPinnedCountriesWithDefaultCountry() {
   /**
    * Pinned countries with out Default country
    */
-  public function testPinnedCountriesWithOutDefaultCountry() {
+  public function testPinnedCountriesWithOutDefaultCountry(): void {
     // Guyana, Netherlands, United States
     $pinnedCountries = ['1093', '1152', '1228'];
 
@@ -833,7 +833,7 @@ public function testPinnedCountriesWithOutDefaultCountry() {
   /**
    * Test dev/core#2379 fix - geocodes shouldn't be > 14 characters.
    */
-  public function testLongGeocodes() {
+  public function testLongGeocodes(): void {
     $contactId = $this->individualCreate();
 
     $fixParams = [
diff --git a/tests/phpunit/CRM/Core/BAO/CacheTest.php b/tests/phpunit/CRM/Core/BAO/CacheTest.php
index c11a7912c7a9..bab5c1707148 100644
--- a/tests/phpunit/CRM/Core/BAO/CacheTest.php
+++ b/tests/phpunit/CRM/Core/BAO/CacheTest.php
@@ -29,7 +29,7 @@ public function createSimpleCache() {
     );
   }
 
-  public function testMultiVersionDecode() {
+  public function testMultiVersionDecode(): void {
     $encoders = ['serialize', ['CRM_Core_BAO_Cache', 'encode']];
     $values = [NULL, 0, 1, TRUE, FALSE, [], ['abcd'], 'ab;cd', new stdClass()];
     foreach ($encoders as $encoder) {
diff --git a/tests/phpunit/CRM/Core/BAO/ConfigSettingTest.php b/tests/phpunit/CRM/Core/BAO/ConfigSettingTest.php
index 47c112b5755f..7b328201336b 100644
--- a/tests/phpunit/CRM/Core/BAO/ConfigSettingTest.php
+++ b/tests/phpunit/CRM/Core/BAO/ConfigSettingTest.php
@@ -15,7 +15,7 @@
  */
 class CRM_Core_BAO_ConfigSettingTest extends CiviUnitTestCase {
 
-  public function testToggleComponent() {
+  public function testToggleComponent(): void {
     $origNames = [];
     foreach (CRM_Core_Component::getEnabledComponents() as $c) {
       $origNames[] = $c->name;
diff --git a/tests/phpunit/CRM/Core/BAO/CustomFieldTest.php b/tests/phpunit/CRM/Core/BAO/CustomFieldTest.php
index 0ca6ea7229f7..ca77e5441e68 100644
--- a/tests/phpunit/CRM/Core/BAO/CustomFieldTest.php
+++ b/tests/phpunit/CRM/Core/BAO/CustomFieldTest.php
@@ -53,7 +53,7 @@ public function testCreateCustomField(): void {
   /**
    * Test changing a data type from multiple-choice to Text.
    */
-  public function testChangeDataType() {
+  public function testChangeDataType(): void {
     $customGroup = $this->createCustomField();
     $fields = [
       'label' => 'Radio to Text',
@@ -81,7 +81,7 @@ public function testChangeDataType() {
   /**
    * Test custom field create accepts passed column name.
    */
-  public function testCreateCustomFieldColumnName() {
+  public function testCreateCustomFieldColumnName(): void {
     $customGroup = $this->customGroupCreate(['extends' => 'Individual']);
     $fields = [
       'label' => 'testFld 2',
@@ -104,7 +104,7 @@ public function testCreateCustomFieldColumnName() {
   /**
    * Test that name is used for the column.
    */
-  public function testCreateCustomFieldName() {
+  public function testCreateCustomFieldName(): void {
     $customGroup = $this->customGroupCreate(['extends' => 'Individual']);
     $fields = [
       'label' => 'testFld 2',
@@ -127,7 +127,7 @@ public function testCreateCustomFieldName() {
   /**
    * Test get fields function.
    */
-  public function testGetFields() {
+  public function testGetFields(): void {
     $customGroup = $this->customGroupCreate(['extends' => 'Individual']);
     $fields = [
       'label' => 'testFld1',
@@ -158,7 +158,7 @@ public function testGetFields() {
   /**
    * @throws \Exception
    */
-  public function testGetDisplayedValues() {
+  public function testGetDisplayedValues(): void {
     $customGroup = $this->customGroupCreate(['extends' => 'Individual']);
     $fieldsToCreate = [
       [
@@ -249,7 +249,7 @@ public function testGetDisplayedValues() {
    * @throws \CRM_Core_Exception
    * @throws \Exception
    */
-  public function testGetDisplayedValuesContactRef() {
+  public function testGetDisplayedValuesContactRef(): void {
     $customGroup = $this->customGroupCreate(['extends' => 'Individual']);
     $params = [
       'data_type' => 'ContactReference',
@@ -269,7 +269,7 @@ public function testGetDisplayedValuesContactRef() {
     $this->customGroupDelete($customGroup['id']);
   }
 
-  public function testDeleteCustomField() {
+  public function testDeleteCustomField(): void {
     $customGroup = $this->customGroupCreate(['extends' => 'Individual']);
     $fields = [
       'custom_group_id' => $customGroup['id'],
@@ -296,7 +296,7 @@ public function testDeleteCustomField() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testMoveField() {
+  public function testMoveField(): void {
     $countriesByName = array_flip(CRM_Core_PseudoConstant::country(FALSE, FALSE));
     $this->assertTrue($countriesByName['Andorra'] > 0);
     $groups = [
@@ -427,7 +427,7 @@ public function testMoveField() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testGetCustomFieldID() {
+  public function testGetCustomFieldID(): void {
     $this->createCustomField();
     $fieldID = CRM_Core_BAO_CustomField::getCustomFieldID('testFld');
     $this->assertEquals($this->customFieldID, $fieldID);
@@ -473,7 +473,7 @@ protected function createCustomField($groupTitle = 'new custom group') {
    *
    * @throws \Exception
    */
-  public function testGetFieldsForImport() {
+  public function testGetFieldsForImport(): void {
     $this->createCustomGroupWithFieldsOfAllTypes();
     $customGroupID = $this->ids['CustomGroup']['Custom Group'];
     $expected = [
@@ -1004,7 +1004,7 @@ public function testFileDisplayValueNoDescription(): void {
   /**
    * Test for hook_civicrm_alterCustomFieldDisplayValue().
    */
-  public function testAlterCustomFieldDisplayValueHook() {
+  public function testAlterCustomFieldDisplayValueHook(): void {
     CRM_Utils_Hook_UnitTests::singleton()->setHook('civicrm_alterCustomFieldDisplayValue', [$this, 'alterCustomFieldDisplayValue']);
     $customGroupId = $this->customGroupCreate([
       'extends' => 'Individual',
@@ -1051,7 +1051,7 @@ public function alterCustomFieldDisplayValue(&$displayValue, $value, $entityId,
    * Test for single select Autocomplete custom field.
    *
    */
-  public function testSingleSelectAutoComplete() {
+  public function testSingleSelectAutoComplete(): void {
     $customGroupId = $this->customGroupCreate([
       'extends' => 'Individual',
     ])['id'];
@@ -1072,7 +1072,7 @@ public function testSingleSelectAutoComplete() {
    * Test for multi select Autocomplete custom field.
    *
    */
-  public function testMultiSelectAutoComplete() {
+  public function testMultiSelectAutoComplete(): void {
     $customGroupId = $this->customGroupCreate([
       'extends' => 'Individual',
     ])['id'];
diff --git a/tests/phpunit/CRM/Core/BAO/CustomGroupTest.php b/tests/phpunit/CRM/Core/BAO/CustomGroupTest.php
index 473edd46dfb6..43ec4a488200 100644
--- a/tests/phpunit/CRM/Core/BAO/CustomGroupTest.php
+++ b/tests/phpunit/CRM/Core/BAO/CustomGroupTest.php
@@ -30,7 +30,7 @@ public function tearDown(): void {
   /**
    * Test getTree().
    */
-  public function testGetTree() {
+  public function testGetTree(): void {
     $customGroup = $this->CustomGroupCreate();
     $customField = $this->customFieldCreate(['custom_group_id' => $customGroup['id']]);
     $result = CRM_Core_BAO_CustomGroup::getTree('Individual', NULL, $customGroup['id']);
@@ -43,7 +43,7 @@ public function testGetTree() {
    * Note that the function seems to support a range of formats so 3 are tested. Yay for
    * inconsistency.
    */
-  public function testGetTreeContactSubType() {
+  public function testGetTreeContactSubType(): void {
     $contactType = $this->callAPISuccess('ContactType', 'create', ['name' => 'Big Bank', 'label' => 'biggee', 'parent_id' => 'Organization']);
     $customGroup = $this->CustomGroupCreate(['extends' => 'Organization', 'extends_entity_column_value' => ['Big_Bank']]);
     $customField = $this->customFieldCreate(['custom_group_id' => $customGroup['id']]);
@@ -67,7 +67,7 @@ public function testGetTreeContactSubType() {
   /**
    * Test calling getTree for a custom field extending a renamed contact type.
    */
-  public function testGetTreeContactSubTypeForNameChangedContactType() {
+  public function testGetTreeContactSubTypeForNameChangedContactType(): void {
     $contactType = $this->callAPISuccess('ContactType', 'create', ['name' => 'Big Bank', 'label' => 'biggee', 'parent_id' => 'Organization']);
     CRM_Core_DAO::executeQuery('UPDATE civicrm_contact_type SET label = "boo" WHERE name = "Organization"');
     $customGroup = $this->CustomGroupCreate(['extends' => 'Organization', 'extends_entity_column_value' => ['Big_Bank']]);
@@ -81,7 +81,7 @@ public function testGetTreeContactSubTypeForNameChangedContactType() {
   /**
    * Test calling getTree for a custom field extending a disabled contact type.
    */
-  public function testGetTreeContactSubTypeForDisabledChangedContactType() {
+  public function testGetTreeContactSubTypeForDisabledChangedContactType(): void {
     $contactType = $this->callAPISuccess('ContactType', 'create', ['name' => 'Big Bank', 'label' => 'biggee', 'parent_id' => 'Organization']);
     $customGroup = $this->CustomGroupCreate(['extends' => 'Organization', 'extends_entity_column_value' => ['Big_Bank']]);
     $customField = $this->customFieldCreate(['custom_group_id' => $customGroup['id']]);
@@ -95,7 +95,7 @@ public function testGetTreeContactSubTypeForDisabledChangedContactType() {
   /**
    * Test calling GetTree for a custom field extending multiple subTypes.
    */
-  public function testGetTreetContactSubTypeForMultipleSubTypes() {
+  public function testGetTreetContactSubTypeForMultipleSubTypes(): void {
     $contactType1 = $this->callAPISuccess('ContactType', 'create', ['name' => 'Big Bank', 'label' => 'biggee', 'parent_id' => 'Organization']);
     $contactType2 = $this->callAPISuccess('ContactType', 'create', ['name' => 'Small Bank', 'label' => 'smallee', 'parent_id' => 'Organization']);
     $customGroup = $this->CustomGroupCreate(['extends' => 'Organization', 'extends_entity_column_value' => ['Big_Bank', 'Small_Bank']]);
@@ -110,7 +110,7 @@ public function testGetTreetContactSubTypeForMultipleSubTypes() {
   /**
    * Test calling GetTree for a custom field that extends a non numerical Event Type.
    */
-  public function testGetTreeEventSubTypeAlphabetical() {
+  public function testGetTreeEventSubTypeAlphabetical(): void {
     $eventType = $this->callAPISuccess('OptionValue', 'Create', ['option_group_id' => 'event_type', 'value' => 'meeting', 'label' => 'Meeting']);
     $customGroup = $this->CustomGroupCreate(['extends' => 'Event', 'extends_entity_column_value' => ['Meeting']]);
     $customField = $this->customFieldCreate(['custom_group_id' => $customGroup['id']]);
@@ -126,7 +126,7 @@ public function testGetTreeEventSubTypeAlphabetical() {
    * Note that the function seems to support a range of formats so 3 are tested. Yay for
    * inconsistency.
    */
-  public function testGetTreeCampaignSubType() {
+  public function testGetTreeCampaignSubType(): void {
     $sep = CRM_Core_DAO::VALUE_SEPARATOR;
     $this->campaignCreate();
     $this->campaignCreate();
@@ -143,7 +143,7 @@ public function testGetTreeCampaignSubType() {
   /**
    * Test calling getTree with contact subtype data.
    */
-  public function testGetTreeActivitySubType() {
+  public function testGetTreeActivitySubType(): void {
     $customGroup = $this->CustomGroupCreate(['extends' => 'Activity', 'extends_entity_column_value' => 1]);
     $customField = $this->customFieldCreate(['custom_group_id' => $customGroup['id']]);
     $result = CRM_Core_BAO_CustomGroup::getTree('Activity', NULL, NULL, NULL, 1);
@@ -162,7 +162,7 @@ public function testRetrieveEmptyParams(): void {
   /**
    * Test retrieve() with Inalid Params
    */
-  public function testRetrieveInvalidParams() {
+  public function testRetrieveInvalidParams(): void {
     $params = ['id' => 99];
     $customGroup = CRM_Core_BAO_CustomGroup::retrieve($params, $dafaults);
     $this->assertNull($customGroup, 'Check that no custom Group is retreived');
@@ -171,7 +171,7 @@ public function testRetrieveInvalidParams() {
   /**
    * Test retrieve()
    */
-  public function testRetrieve() {
+  public function testRetrieve(): void {
     $customGroupTitle = 'Custom Group';
     $groupParams = [
       'title' => $customGroupTitle,
@@ -193,7 +193,7 @@ public function testRetrieve() {
   /**
    * Test getGroupDetail() with Empty Params
    */
-  public function testGetGroupDetailEmptyParams() {
+  public function testGetGroupDetailEmptyParams(): void {
     $customGroupId = [];
     $customGroup = CRM_Core_BAO_CustomGroup::getGroupDetail($customGroupId);
     $this->assertTrue(empty($customGroup), 'Check that no custom Group  details is retreived');
@@ -202,7 +202,7 @@ public function testGetGroupDetailEmptyParams() {
   /**
    * Test getGroupDetail with Invalid Params.
    */
-  public function testGetGroupDetailInvalidParams() {
+  public function testGetGroupDetailInvalidParams(): void {
     $customGroupId = 99;
     $customGroup = CRM_Core_BAO_CustomGroup::getGroupDetail($customGroupId);
     $this->assertTrue(empty($customGroup), 'Check that no custom Group  details is retreived');
@@ -211,7 +211,7 @@ public function testGetGroupDetailInvalidParams() {
   /**
    * Test getGroupDetail().
    */
-  public function testGetGroupDetail() {
+  public function testGetGroupDetail(): void {
     $customGroupTitle = 'My Custom Group';
     $groupParams = [
       'title' => $customGroupTitle,
@@ -262,7 +262,7 @@ public function testGetGroupDetail() {
   /**
    * Test getTitle() with Invalid Params()
    */
-  public function testGetTitleWithInvalidParams() {
+  public function testGetTitleWithInvalidParams(): void {
     $params = 99;
     $customGroupTitle = CRM_Core_BAO_CustomGroup::getTitle($params);
 
@@ -272,7 +272,7 @@ public function testGetTitleWithInvalidParams() {
   /**
    * Test getTitle()
    */
-  public function testGetTitle() {
+  public function testGetTitle(): void {
     $customGroupTitle = 'Custom Group';
     $groupParams = [
       'title' => $customGroupTitle,
@@ -297,7 +297,7 @@ public function testGetTitle() {
   /**
    * Test deleteGroup.
    */
-  public function testDeleteGroup() {
+  public function testDeleteGroup(): void {
     $customGroupTitle = 'My Custom Group';
     $groupParams = [
       'title' => $customGroupTitle,
@@ -362,7 +362,7 @@ public function testCreateTable(): void {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testCheckCustomField() {
+  public function testCheckCustomField(): void {
     $groupParams = [
       'title' => 'My Custom Group',
       'name' => 'my_custom_group',
@@ -425,7 +425,7 @@ public function testGetActiveGroupsWithInvalidParams(): void {
     $this->assertEquals(empty($activeGroups), TRUE, 'Check that Emprt params are retreived');
   }
 
-  public function testGetActiveGroups() {
+  public function testGetActiveGroups(): void {
     $contactId = $this->individualCreate();
     $customGroupTitle = 'Custom Group';
     $groupParams = [
@@ -514,7 +514,7 @@ public function testCreateTableName(): void {
   /**
    * Test isGroupEmpty()
    */
-  public function testIsGroupEmpty() {
+  public function testIsGroupEmpty(): void {
     $customGroupTitle = 'Test Custom Group';
     $groupParams = [
       'title' => $customGroupTitle,
@@ -536,7 +536,7 @@ public function testIsGroupEmpty() {
   /**
    * Test getGroupTitles() with Invalid Params()
    */
-  public function testGetGroupTitlesWithInvalidParams() {
+  public function testGetGroupTitlesWithInvalidParams(): void {
     $params = [99];
     $groupTitles = CRM_Core_BAO_CustomGroup::getGroupTitles($params);
     $this->assertTrue(empty($groupTitles), 'Check that no titles are received');
@@ -545,7 +545,7 @@ public function testGetGroupTitlesWithInvalidParams() {
   /**
    * Test getGroupTitles()
    */
-  public function testGetGroupTitles() {
+  public function testGetGroupTitles(): void {
     $groupParams = [
       'title' => 'Test Group',
       'name' => 'test_custom_group',
@@ -581,7 +581,7 @@ public function testGetGroupTitles() {
   /**
    * Test that passed dates are extracted from the url when processing custom data.
    */
-  public function testExtractGetParamsReturnsDates() {
+  public function testExtractGetParamsReturnsDates(): void {
     // Create a custom group to contain the custom field.
     $groupParams = [
       'title' => 'My Custom Group',
@@ -657,7 +657,7 @@ public function testAllowedGroupNames(string $extends, string $name, bool $isAll
     $this->assertEquals($expectedName, $group->name);
   }
 
-  public function testCustomGroupExtends() {
+  public function testCustomGroupExtends(): void {
     $extends = \CRM_Core_SelectValues::customGroupExtends();
     $this->assertArrayHasKey('Contribution', $extends);
     $this->assertArrayHasKey('Case', $extends);
@@ -671,7 +671,7 @@ public function testCustomGroupExtends() {
     $this->assertArrayHasKey('ParticipantEventType', $extends);
   }
 
-  public function testMapTableName() {
+  public function testMapTableName(): void {
     $this->assertEquals('civicrm_case', CRM_Core_BAO_CustomGroup::mapTableName('Case'));
     $this->assertEquals('civicrm_contact', CRM_Core_BAO_CustomGroup::mapTableName('Contact'));
     $this->assertEquals('civicrm_contact', CRM_Core_BAO_CustomGroup::mapTableName('Individual'));
diff --git a/tests/phpunit/CRM/Core/BAO/CustomQueryTest.php b/tests/phpunit/CRM/Core/BAO/CustomQueryTest.php
index c7a0ef4df47a..678c32a30c07 100644
--- a/tests/phpunit/CRM/Core/BAO/CustomQueryTest.php
+++ b/tests/phpunit/CRM/Core/BAO/CustomQueryTest.php
@@ -27,7 +27,7 @@ public function tearDown(): void {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testSearchCustomDataDateRelative() {
+  public function testSearchCustomDataDateRelative(): void {
     $ids = $this->entityCustomGroupWithSingleFieldCreate(__FUNCTION__, 'ContactTestTest');
     $dateCustomField = $this->customFieldCreate([
       'custom_group_id' => $ids['custom_group_id'],
@@ -99,7 +99,7 @@ public function testSearchCustomDataDateRelative() {
    * @throws \CRM_Core_Exception
    * @throws \Civi\API\Exception\UnauthorizedException
    */
-  public function testSearchCustomDataDateHighLow() {
+  public function testSearchCustomDataDateHighLow(): void {
     $this->createCustomGroupWithFieldOfType([], 'date');
     $dateCustomFieldName = $this->getCustomFieldName('date');
     // Assigning the relevant form value to be within a custom key is normally done in
@@ -132,7 +132,7 @@ public function testSearchCustomDataDateHighLow() {
    * @throws \CRM_Core_Exception
    * @throws \Civi\API\Exception\UnauthorizedException
    */
-  public function testSearchCustomDataDateLowWithPermsInPlay() {
+  public function testSearchCustomDataDateLowWithPermsInPlay(): void {
     $this->createLoggedInUser();
     CRM_Core_Config::singleton()->userPermissionClass->permissions = ['view all contacts', 'access all custom data'];
     $this->createCustomGroupWithFieldOfType([], 'date');
@@ -166,7 +166,7 @@ public function testSearchCustomDataDateLowWithPermsInPlay() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testSearchCustomDataDateFromTo() {
+  public function testSearchCustomDataDateFromTo(): void {
     $ids = $this->entityCustomGroupWithSingleFieldCreate(__FUNCTION__, 'ContactTestTest');
     $dateCustomField = $this->customFieldCreate([
       'custom_group_id' => $ids['custom_group_id'],
@@ -203,7 +203,7 @@ public function testSearchCustomDataDateFromTo() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testSearchCustomDataFromTo() {
+  public function testSearchCustomDataFromTo(): void {
     $ids = $this->entityCustomGroupWithSingleFieldCreate(__FUNCTION__, 'ContactTestTest');
     $datas = [
       'Int' => 2,
@@ -247,7 +247,7 @@ public function testSearchCustomDataFromTo() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testLocalizedSearchCustomDataFromTo() {
+  public function testLocalizedSearchCustomDataFromTo(): void {
     $this->setMonetaryDecimalPoint(',');
     $this->setMonetaryThousandSeparator('.');
     $ids = $this->entityCustomGroupWithSingleFieldCreate(__FUNCTION__, 'ContactTestTest');
@@ -299,7 +299,7 @@ public function testLocalizedSearchCustomDataFromTo() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testSearchCustomDataFromAndTo() {
+  public function testSearchCustomDataFromAndTo(): void {
     $ids = $this->entityCustomGroupWithSingleFieldCreate(__FUNCTION__, 'ContactTestTest');
     $dataSet = [
       'Date' => ['value' => '2015-06-06', 'sql_string' => '"20150606235959"', 'qill_string' => "'June 6th, 2015 11:59 PM'", 'qill_string_greater' => "'June 6th, 2015 12:00 AM'"],
@@ -374,7 +374,7 @@ public function testSearchCustomDataFromAndTo() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testLocalizedSearchCustomDataFromAndTo() {
+  public function testLocalizedSearchCustomDataFromAndTo(): void {
     $this->setMonetaryDecimalPoint(',');
     $this->setMonetaryThousandSeparator('.');
     $ids = $this->entityCustomGroupWithSingleFieldCreate(__FUNCTION__, 'ContactTestTest');
@@ -455,7 +455,7 @@ public function testLocalizedSearchCustomDataFromAndTo() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testSearchCustomDataDateEquals() {
+  public function testSearchCustomDataDateEquals(): void {
     $ids = $this->entityCustomGroupWithSingleFieldCreate(__FUNCTION__, 'ContactTestTest');
     $dateCustomField = $this->customFieldCreate([
       'custom_group_id' => $ids['custom_group_id'],
@@ -487,7 +487,7 @@ public function testSearchCustomDataDateEquals() {
    * @throws \CRM_Core_Exception
    * @throws \Civi\API\Exception\UnauthorizedException
    */
-  public function testAddressCustomFields() {
+  public function testAddressCustomFields(): void {
     $this->createCustomGroupWithFieldOfType(['extends' => 'Address'], 'int');
     $individualID = $this->individualCreate();
     $this->callAPISuccess('Address', 'create', [
diff --git a/tests/phpunit/CRM/Core/BAO/CustomValueTableMultipleTest.php b/tests/phpunit/CRM/Core/BAO/CustomValueTableMultipleTest.php
index 21a283af9af7..f3cbb81e1c48 100644
--- a/tests/phpunit/CRM/Core/BAO/CustomValueTableMultipleTest.php
+++ b/tests/phpunit/CRM/Core/BAO/CustomValueTableMultipleTest.php
@@ -50,7 +50,7 @@ public function testCustomGroupMultipleSingle(): void {
     $this->contactDelete($contactID);
   }
 
-  public function testCustomGroupMultipleDouble() {
+  public function testCustomGroupMultipleDouble(): void {
     $contactID = $this->individualCreate();
     $customGroup = $this->customGroupCreate(['is_multiple' => 1]);
     $fields = [
@@ -82,7 +82,7 @@ public function testCustomGroupMultipleDouble() {
     $this->contactDelete($contactID);
   }
 
-  public function testCustomGroupMultipleUpdate() {
+  public function testCustomGroupMultipleUpdate(): void {
     $contactID = $this->individualCreate();
     $customGroup = $this->customGroupCreate(['is_multiple' => 1]);
     $fields = [
@@ -123,7 +123,7 @@ public function testCustomGroupMultipleUpdate() {
     $this->contactDelete($contactID);
   }
 
-  public function testCustomGroupMultipleOldFormat() {
+  public function testCustomGroupMultipleOldFormat(): void {
     $contactID = $this->individualCreate();
     $customGroup = $this->customGroupCreate(['is_multiple' => 1]);
     $fields = [
diff --git a/tests/phpunit/CRM/Core/BAO/CustomValueTableSetGetTest.php b/tests/phpunit/CRM/Core/BAO/CustomValueTableSetGetTest.php
index 58363e42ca01..4aaa8a5e86dd 100644
--- a/tests/phpunit/CRM/Core/BAO/CustomValueTableSetGetTest.php
+++ b/tests/phpunit/CRM/Core/BAO/CustomValueTableSetGetTest.php
@@ -109,7 +109,7 @@ public function testSetGetValuesDate(): void {
   /**
    * Test setValues() and getValues() methods with custom field YesNo(Boolean) Radio
    */
-  public function testSetGetValuesYesNoRadio() {
+  public function testSetGetValuesYesNoRadio(): void {
     $contactID = $this->individualCreate();
 
     $customGroup = $this->customGroupCreate(['is_multiple' => 1]);
diff --git a/tests/phpunit/CRM/Core/BAO/CustomValueTableTest.php b/tests/phpunit/CRM/Core/BAO/CustomValueTableTest.php
index 7961daca8ccc..03d43b8e4955 100644
--- a/tests/phpunit/CRM/Core/BAO/CustomValueTableTest.php
+++ b/tests/phpunit/CRM/Core/BAO/CustomValueTableTest.php
@@ -14,7 +14,7 @@ public function tearDown(): void {
   /**
    * Test store function for country.
    */
-  public function testStoreCountry() {
+  public function testStoreCountry(): void {
     $params = [];
     $contactID = $this->individualCreate();
     $customGroup = $this->customGroupCreate();
@@ -45,7 +45,7 @@ public function testStoreCountry() {
   /**
    * Test store function for file.
    */
-  public function testStoreFile() {
+  public function testStoreFile(): void {
     $contactID = $this->individualCreate();
     $file = $this->callAPISuccess('File', 'create', ['uri' => 'dummy_data']);
     $customGroup = $this->customGroupCreate();
diff --git a/tests/phpunit/CRM/Core/BAO/CustomValueTest.php b/tests/phpunit/CRM/Core/BAO/CustomValueTest.php
index 98e740ab8054..37189346d706 100644
--- a/tests/phpunit/CRM/Core/BAO/CustomValueTest.php
+++ b/tests/phpunit/CRM/Core/BAO/CustomValueTest.php
@@ -21,7 +21,7 @@
  */
 class CRM_Core_BAO_CustomValueTest extends CiviUnitTestCase {
 
-  public function testTypeCheckWithValidInput() {
+  public function testTypeCheckWithValidInput(): void {
 
     $values = [
       'Memo' => 'Test1',
@@ -45,7 +45,7 @@ public function testTypeCheckWithValidInput() {
     }
   }
 
-  public function testTypeCheckWithInvalidInput() {
+  public function testTypeCheckWithInvalidInput(): void {
     $values = ['check1' => 'chk'];
     foreach ($values as $type => $value) {
       $valid = CRM_Core_BAO_CustomValue::typecheck($type, $value);
@@ -53,7 +53,7 @@ public function testTypeCheckWithInvalidInput() {
     }
   }
 
-  public function testTypeCheckWithWrongInput() {
+  public function testTypeCheckWithWrongInput(): void {
     $values = [
       'String' => 1,
       'Boolean' => 'US',
@@ -64,7 +64,7 @@ public function testTypeCheckWithWrongInput() {
     }
   }
 
-  public function testTypeToFieldWithValidInput() {
+  public function testTypeToFieldWithValidInput(): void {
     $values = [
       'String' => 'char_data',
       'File' => 'char_data',
@@ -85,7 +85,7 @@ public function testTypeToFieldWithValidInput() {
     }
   }
 
-  public function testTypeToFieldWithWrongInput() {
+  public function testTypeToFieldWithWrongInput(): void {
     $values = [
       'String' => 'memo_data',
       'File' => 'date_data',
@@ -97,7 +97,7 @@ public function testTypeToFieldWithWrongInput() {
     }
   }
 
-  public function testFixCustomFieldValue() {
+  public function testFixCustomFieldValue(): void {
     $customGroup = $this->customGroupCreate(['extends' => 'Individual']);
     $params = [
       'email' => 'abc@example.com',
@@ -154,7 +154,7 @@ public function testFixCustomFieldValue() {
     $this->customGroupDelete($customGroup['id']);
   }
 
-  public function testFixCustomFieldValueWithEmptyParams() {
+  public function testFixCustomFieldValueWithEmptyParams(): void {
     $params = [];
     $result = CRM_Core_BAO_CustomValue::fixCustomFieldValue($params);
     $this->assertEquals($result, NULL, 'Checking the returned value of type Memo.');
diff --git a/tests/phpunit/CRM/Core/BAO/EmailTest.php b/tests/phpunit/CRM/Core/BAO/EmailTest.php
index 8a0f96e13af3..40696634bd3b 100644
--- a/tests/phpunit/CRM/Core/BAO/EmailTest.php
+++ b/tests/phpunit/CRM/Core/BAO/EmailTest.php
@@ -21,7 +21,7 @@ public function setUp(): void {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testCreate() {
+  public function testCreate(): void {
     $contactId = $this->individualCreate();
     $params = [
       'email' => 'jane.doe@example.com',
@@ -59,7 +59,7 @@ public function testCreate() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testHoldEmail() {
+  public function testHoldEmail(): void {
     $contactId = $this->individualCreate();
 
     $params = [
@@ -154,7 +154,7 @@ public function testHoldEmail() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testAllEmails() {
+  public function testAllEmails(): void {
     $contactParams = [
       'first_name' => 'Alan',
       'last_name' => 'Smith',
@@ -182,7 +182,7 @@ public function testAllEmails() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testGetFromEmail() {
+  public function testGetFromEmail(): void {
     $this->createLoggedInUser();
     $fromEmails = CRM_Core_BAO_Email::getFromEmail();
     $emails = array_values($fromEmails);
diff --git a/tests/phpunit/CRM/Core/BAO/FinancialTrxnTest.php b/tests/phpunit/CRM/Core/BAO/FinancialTrxnTest.php
index d503dcdd1efb..5ccb5a027699 100644
--- a/tests/phpunit/CRM/Core/BAO/FinancialTrxnTest.php
+++ b/tests/phpunit/CRM/Core/BAO/FinancialTrxnTest.php
@@ -27,7 +27,7 @@ public function tearDown(): void {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testCreate() {
+  public function testCreate(): void {
     $contactId = $this->individualCreate();
     $financialTypeId = 1;
     $contributionID = $this->contributionCreate([
@@ -193,7 +193,7 @@ public function testUpdateCreditCardDetailsUsingContributionAPI(): void {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testUpdateCreditCardDetails() {
+  public function testUpdateCreditCardDetails(): void {
     $cid = $this->individualCreate();
     $params = [
       'contact_id' => $cid,
@@ -229,7 +229,7 @@ public function testUpdateCreditCardDetails() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testGetContributionBalance() {
+  public function testGetContributionBalance(): void {
     //create the contribution that isn't paid yet
     $contactId = $this->individualCreate();
     $params = [
@@ -259,7 +259,7 @@ public function testGetContributionBalance() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testFeeAmountTrxns() {
+  public function testFeeAmountTrxns(): void {
     $contactId = $this->individualCreate();
 
     // Get the expected financial account of a payment made with a credit card.
diff --git a/tests/phpunit/CRM/Core/BAO/IMTest.php b/tests/phpunit/CRM/Core/BAO/IMTest.php
index 9b56f1568f33..3105f89ffa5b 100644
--- a/tests/phpunit/CRM/Core/BAO/IMTest.php
+++ b/tests/phpunit/CRM/Core/BAO/IMTest.php
@@ -11,7 +11,7 @@ class CRM_Core_BAO_IMTest extends CiviUnitTestCase {
   /**
    * Create() method (create and update modes)
    */
-  public function testCreate() {
+  public function testCreate(): void {
     $contactId = $this->individualCreate();
 
     $params = [
@@ -50,7 +50,7 @@ public function testCreate() {
   /**
    * AllIMs() method - get all IMs for our contact, with primary IM first
    */
-  public function testAllIMs() {
+  public function testAllIMs(): void {
     $this->loadXMLDataSet(dirname(__FILE__) . '/dataset/im_test.xml');
 
     $contactId = 69;
diff --git a/tests/phpunit/CRM/Core/BAO/MappingTest.php b/tests/phpunit/CRM/Core/BAO/MappingTest.php
index fee5ff7179c9..3d080460bcf4 100644
--- a/tests/phpunit/CRM/Core/BAO/MappingTest.php
+++ b/tests/phpunit/CRM/Core/BAO/MappingTest.php
@@ -222,7 +222,7 @@ public function getMappingMaps() {
   /**
    * Ensure getCreateMappingValues() doesn't return an error when there are spaces in the name.
    */
-  public function testGetCreateMappingValues() {
+  public function testGetCreateMappingValues(): void {
     CRM_Core_BAO_Mapping::getCreateMappingValues("Import Multi value custom data");
   }
 
diff --git a/tests/phpunit/CRM/Core/BAO/NavigationTest.php b/tests/phpunit/CRM/Core/BAO/NavigationTest.php
index b865fa6055e8..3ede2f914e2a 100644
--- a/tests/phpunit/CRM/Core/BAO/NavigationTest.php
+++ b/tests/phpunit/CRM/Core/BAO/NavigationTest.php
@@ -19,7 +19,7 @@ public function setUp(): void {
   /**
    * Test that a missing report menu link is added by rebuildReportsNavigation.
    */
-  public function testCreateMissingReportMenuItemLink() {
+  public function testCreateMissingReportMenuItemLink(): void {
     $reportCount = $this->getCountReportInstances();
     CRM_Core_DAO::executeQuery("DELETE FROM civicrm_navigation WHERE url LIKE 'civicrm/report/instance/1?reset=1%'");
     $this->assertEquals($reportCount - 1, $this->getCountReportInstances());
@@ -36,7 +36,7 @@ public function testCreateMissingReportMenuItemLink() {
   /**
    * Test that a link with output=criteria at the end is not duplicated.
    */
-  public function testNoDuplicateReportMenuItemLink() {
+  public function testNoDuplicateReportMenuItemLink(): void {
     CRM_Core_BAO_Navigation::rebuildReportsNavigation(CRM_Core_Config::domainID());
     $reportCount = $this->getCountReportInstances();
     CRM_Core_DAO::executeQuery("
@@ -56,7 +56,7 @@ public function testNoDuplicateReportMenuItemLink() {
    * both winding up under the Reports menu - since they already exist they should be unchanged
    * by rebuilding reports.
    */
-  public function testNoDuplicateAllReportsLink() {
+  public function testNoDuplicateAllReportsLink(): void {
     $existing_links = $this->callAPISuccess('Navigation', 'get', ['label' => 'All Reports', 'sequential' => 1]);
     $this->assertNotEquals($existing_links['values'][0]['parent_id'], $existing_links['values'][1]['parent_id']);
     CRM_Core_BAO_Navigation::rebuildReportsNavigation(CRM_Core_Config::domainID());
@@ -70,7 +70,7 @@ public function testNoDuplicateAllReportsLink() {
    *
    * Function tests CRM_Core_BAO_Navigation::rebuildReportsNavigation.
    */
-  public function testUpdateExistingReportMenuLink() {
+  public function testUpdateExistingReportMenuLink(): void {
     $url = 'civicrm/report/instance/1';
     $url_params = 'reset=1';
     $existing_nav = CRM_Core_BAO_Navigation::getNavItemByUrl($url, $url_params);
@@ -93,7 +93,7 @@ public function testUpdateExistingReportMenuLink() {
   /**
    * Test that a navigation item can be retrieved by it's url.
    */
-  public function testGetNavItemByUrl() {
+  public function testGetNavItemByUrl(): void {
     $random_string = substr(sha1(rand()), 0, 7);
     $name = "Test Menu Link {$random_string}";
     $url = "civicrm/test/{$random_string}";
@@ -121,7 +121,7 @@ public function testGetNavItemByUrl() {
    * We want to be able to get a report url with OR without the output=criteria since
    * that is part of the navigation but not the instance.
    */
-  public function testGetNavItemByUrlWildcard() {
+  public function testGetNavItemByUrlWildcard(): void {
     $random_string = substr(sha1(rand()), 0, 7);
     $name = "Test Menu Link {$random_string}";
     $url = "civicrm/test/{$random_string}";
@@ -168,7 +168,7 @@ protected function getCountURL($url) {
    * Run fixNavigationMenu() on a menu which already has navIDs
    * everywhere. They should be unchanged.
    */
-  public function testFixNavigationMenu_preserveIDs() {
+  public function testFixNavigationMenu_preserveIDs(): void {
     $input[10] = [
       'attributes' => [
         'label' => 'Custom Menu Entry',
@@ -201,7 +201,7 @@ public function testFixNavigationMenu_preserveIDs() {
    * Run fixNavigationMenu() on a menu which is missing some navIDs. They
    * should be filled in, and others should be preserved.
    */
-  public function testFixNavigationMenu_inferIDs() {
+  public function testFixNavigationMenu_inferIDs(): void {
     $input[10] = [
       'attributes' => [
         'label' => 'Custom Menu Entry',
@@ -242,7 +242,7 @@ public function testFixNavigationMenu_inferIDs() {
     $this->assertEquals(100, $output[10]['child'][100]['attributes']['navID']);
   }
 
-  public function testFixNavigationMenu_inferIDs_deep() {
+  public function testFixNavigationMenu_inferIDs_deep(): void {
     $input[10] = [
       'attributes' => [
         'label' => 'Custom Menu Entry',
@@ -287,7 +287,7 @@ public function testFixNavigationMenu_inferIDs_deep() {
   /**
    * Tests that permissions and component status are checked with the correct operator.
    */
-  public function testCheckPermissions() {
+  public function testCheckPermissions(): void {
     $menuItem = [
       'permission' => 'access CiviCRM, access CiviContribute',
       'operator' => 'AND',
diff --git a/tests/phpunit/CRM/Core/BAO/OpenIDTest.php b/tests/phpunit/CRM/Core/BAO/OpenIDTest.php
index 85b5899d440e..726134128a13 100644
--- a/tests/phpunit/CRM/Core/BAO/OpenIDTest.php
+++ b/tests/phpunit/CRM/Core/BAO/OpenIDTest.php
@@ -16,7 +16,7 @@ public function tearDown(): void {
   /**
    * Add() method (create and update modes)
    */
-  public function testAdd() {
+  public function testAdd(): void {
     $contactId = $this->individualCreate();
     $this->assertDBRowExist('CRM_Contact_DAO_Contact', $contactId);
 
@@ -55,7 +55,7 @@ public function testAdd() {
   /**
    * AllOpenIDs() method - get all OpenIDs for the given contact
    */
-  public function testAllOpenIDs() {
+  public function testAllOpenIDs(): void {
     $contactId = $this->individualCreate();
     $this->assertDBRowExist('CRM_Contact_DAO_Contact', $contactId);
 
diff --git a/tests/phpunit/CRM/Core/BAO/OptionGroupTest.php b/tests/phpunit/CRM/Core/BAO/OptionGroupTest.php
index ef9d7d5d5252..cd45b4a04483 100644
--- a/tests/phpunit/CRM/Core/BAO/OptionGroupTest.php
+++ b/tests/phpunit/CRM/Core/BAO/OptionGroupTest.php
@@ -29,7 +29,7 @@ public function setUp(): void {
   /**
    * Ensure only one option value exists after calling ensureOptionValueExists.
    */
-  public function testEnsureOptionGroupExistsExistingValue() {
+  public function testEnsureOptionGroupExistsExistingValue(): void {
     CRM_Core_BAO_OptionGroup::ensureOptionGroupExists(['name' => 'contribution_status']);
     $this->callAPISuccessGetSingle('OptionGroup', ['name' => 'contribution_status']);
   }
@@ -37,7 +37,7 @@ public function testEnsureOptionGroupExistsExistingValue() {
   /**
    * Ensure only one option value exists adds a new value.
    */
-  public function testEnsureOptionGroupExistsNewValue() {
+  public function testEnsureOptionGroupExistsNewValue(): void {
     CRM_Core_BAO_OptionGroup::ensureOptionGroupExists(['name' => 'Bombed']);
     $optionGroups = $this->callAPISuccess('OptionValue', 'getoptions', ['context' => 'validate', 'field' => 'option_group_id'])['values'];
     $this->assertTrue(in_array('bombed', $optionGroups));
diff --git a/tests/phpunit/CRM/Core/BAO/PhoneTest.php b/tests/phpunit/CRM/Core/BAO/PhoneTest.php
index bf1a3734e3ab..9b0d26302041 100644
--- a/tests/phpunit/CRM/Core/BAO/PhoneTest.php
+++ b/tests/phpunit/CRM/Core/BAO/PhoneTest.php
@@ -18,7 +18,7 @@ class CRM_Core_BAO_PhoneTest extends CiviUnitTestCase {
   /**
    * Add() method (create and update modes)
    */
-  public function testAdd() {
+  public function testAdd(): void {
     $contactId = $this->individualCreate();
 
     $params = [
@@ -59,7 +59,7 @@ public function testAdd() {
   /**
    * AllPhones() method - get all Phones for our contact, with primary Phone first.
    */
-  public function testAllPhones() {
+  public function testAllPhones(): void {
     $contactParams = [
       'first_name' => 'Alan',
       'last_name' => 'Smith',
diff --git a/tests/phpunit/CRM/Core/BAO/PreferencesTest.php b/tests/phpunit/CRM/Core/BAO/PreferencesTest.php
index 56ed1cf814f4..22cb1bad4207 100644
--- a/tests/phpunit/CRM/Core/BAO/PreferencesTest.php
+++ b/tests/phpunit/CRM/Core/BAO/PreferencesTest.php
@@ -15,7 +15,7 @@
  */
 class CRM_Core_BAO_PreferencesTest extends CiviUnitTestCase {
 
-  public function testValueOptions() {
+  public function testValueOptions(): void {
 
     $addressOptions = CRM_Core_BAO_Setting::valueOptions(CRM_Core_BAO_Setting::SYSTEM_PREFERENCES_NAME,
       'address_options'
diff --git a/tests/phpunit/CRM/Core/BAO/PrevNextCacheTest.php b/tests/phpunit/CRM/Core/BAO/PrevNextCacheTest.php
index 3c1e92fc8b63..895996580b0a 100644
--- a/tests/phpunit/CRM/Core/BAO/PrevNextCacheTest.php
+++ b/tests/phpunit/CRM/Core/BAO/PrevNextCacheTest.php
@@ -15,7 +15,7 @@
  */
 class CRM_Core_BAO_PrevNextCacheTest extends CiviUnitTestCase {
 
-  public function testFlipData() {
+  public function testFlipData(): void {
     $dao = new CRM_Core_BAO_PrevNextCache();
     $dao->entity_id1 = 1;
     $dao->entity_id2 = 2;
diff --git a/tests/phpunit/CRM/Core/BAO/RecurringEntityTest.php b/tests/phpunit/CRM/Core/BAO/RecurringEntityTest.php
index a20b8cd6a4ba..4c0e73c06616 100644
--- a/tests/phpunit/CRM/Core/BAO/RecurringEntityTest.php
+++ b/tests/phpunit/CRM/Core/BAO/RecurringEntityTest.php
@@ -23,7 +23,7 @@ public function tearDown(): void {
   /**
    * Testing Activity Generation through Entity Recursion.
    */
-  public function testActivityGeneration() {
+  public function testActivityGeneration(): void {
     //Activity set initial params
     $daoActivity = new CRM_Activity_DAO_Activity();
     $daoActivity->activity_type_id = 1;
@@ -144,7 +144,7 @@ public function testRepeatEventCreation(): void {
   /**
    * Testing Event Generation through Entity Recursion.
    */
-  public function testEventGeneration() {
+  public function testEventGeneration(): void {
     //Event set initial params
     $daoEvent = new CRM_Event_DAO_Event();
     $daoEvent->title = 'Test event for Recurring Entity';
@@ -294,7 +294,7 @@ public function testEventGeneration() {
   /**
    * Testing Activity Generation through Entity Recursion with Custom Data and Tags.
    */
-  public function testRecurringEntityGenerationWithCustomDataAndTags() {
+  public function testRecurringEntityGenerationWithCustomDataAndTags(): void {
 
     // Create custom group and field
     $customGroup = $this->customGroupCreate([
@@ -373,7 +373,7 @@ public function testRecurringEntityGenerationWithCustomDataAndTags() {
   /**
    * Testing Activity Generation through Entity Recursion with minute units.
    */
-  public function testRecurringEntityGenerationWithMinuteUnit() {
+  public function testRecurringEntityGenerationWithMinuteUnit(): void {
     // Create original activity
     $activityDateTime = '2021-11-11 15:00:00';
     $activityId = $this->activityCreate([
diff --git a/tests/phpunit/CRM/Core/BAO/SettingTest.php b/tests/phpunit/CRM/Core/BAO/SettingTest.php
index 3aecff724747..79ed20f4b812 100644
--- a/tests/phpunit/CRM/Core/BAO/SettingTest.php
+++ b/tests/phpunit/CRM/Core/BAO/SettingTest.php
@@ -44,7 +44,7 @@ public function tearDown(): void {
   /**
    * Test that enabling a valid component works.
    */
-  public function testEnableComponentValid() {
+  public function testEnableComponentValid(): void {
     CRM_Core_Config::singleton(TRUE, TRUE);
     $result = CRM_Core_BAO_ConfigSetting::enableComponent('CiviCampaign');
     $this->assertTrue($result);
@@ -53,7 +53,7 @@ public function testEnableComponentValid() {
   /**
    * Test that we get a success result if we try to enable an enabled component.
    */
-  public function testEnableComponentAlreadyPresent() {
+  public function testEnableComponentAlreadyPresent(): void {
     CRM_Core_Config::singleton(TRUE, TRUE);
     CRM_Core_BAO_ConfigSetting::enableComponent('CiviCampaign');
     $result = CRM_Core_BAO_ConfigSetting::enableComponent('CiviCampaign');
@@ -63,7 +63,7 @@ public function testEnableComponentAlreadyPresent() {
   /**
    * Test that we get a false result if we try to enable an invalid component.
    */
-  public function testEnableComponentInvalid() {
+  public function testEnableComponentInvalid(): void {
     CRM_Core_Config::singleton(TRUE, TRUE);
     $result = CRM_Core_BAO_ConfigSetting::enableComponent('CiviFake');
     $this->assertFalse($result);
@@ -82,7 +82,7 @@ public function testEnableComponentInvalid() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testHandlingOfContributionInvoiceSetting() {
+  public function testHandlingOfContributionInvoiceSetting(): void {
     $contributionSettings = [
       'invoice_prefix' => 'G_',
       'credit_notes_prefix' => 'XX_',
@@ -117,7 +117,7 @@ public function testHandlingOfContributionInvoiceSetting() {
    * Ensure that overrides in $civicrm_setting apply when
    * using getItem($group,$name).
    */
-  public function testGetItem_Override() {
+  public function testGetItem_Override(): void {
     global $civicrm_setting;
     $civicrm_setting[CRM_Core_BAO_Setting::DIRECTORY_PREFERENCES_NAME]['imageUploadDir'] = '/test/override';
     Civi::service('settings_manager')->useMandatory();
@@ -140,7 +140,7 @@ public function testGetItem_Override() {
     CRM_Core_DAO::executeQuery($query);
   }
 
-  public function testDefaults() {
+  public function testDefaults(): void {
     CRM_Core_DAO::executeQuery('DELETE FROM civicrm_setting WHERE name = "max_attachments"');
     Civi::service('settings_manager')->flush();
     $this->assertEquals(3, Civi::settings()->get('max_attachments'));
@@ -154,7 +154,7 @@ public function testDefaults() {
    * are very similar, but they exercise different codepaths. The first uses the API
    * and setItems [plural]; the second uses setItem [singular].
    */
-  public function testOnChange() {
+  public function testOnChange(): void {
     global $_testOnChange_hookCalls;
     $this->setMockSettingsMetaData([
       'onChangeExample' => [
@@ -213,7 +213,7 @@ public static function _testOnChange_onChangeExample($oldValue, $newValue, $meta
    * Test to set isProductionEnvironment
    *
    */
-  public function testSetCivicrmEnvironment() {
+  public function testSetCivicrmEnvironment(): void {
     Civi::settings()->set('environment', 'Staging');
     $values = Civi::settings()->get('environment');
     $this->assertEquals('Staging', $values);
@@ -227,7 +227,7 @@ public function testSetCivicrmEnvironment() {
   /**
    * Test that options defined as a pseudoconstant can be converted to options.
    */
-  public function testPseudoConstants() {
+  public function testPseudoConstants(): void {
     $this->contributionPageCreate();
     $metadata = \Civi\Core\SettingsMetadata::getMetadata(['name' => ['default_invoice_page']], NULL, TRUE);
     $this->assertEquals('Test Contribution Page', $metadata['default_invoice_page']['options'][1]);
diff --git a/tests/phpunit/CRM/Core/BAO/TagTest.php b/tests/phpunit/CRM/Core/BAO/TagTest.php
index c3672c0d45e8..fa395dba0343 100644
--- a/tests/phpunit/CRM/Core/BAO/TagTest.php
+++ b/tests/phpunit/CRM/Core/BAO/TagTest.php
@@ -1,149 +1,149 @@
-<?php
-
-/**
- * Class CRM_Core_BAO_TagTest
- * @group headless
- */
-class CRM_Core_BAO_TagTest extends CiviUnitTestCase {
-
-  /**
-   * Set up for class.
-   *
-   * @throws \CRM_Core_Exception
-   */
-  public function setUp(): void {
-    parent::setUp();
-    $this->quickCleanup(['civicrm_tag']);
-
-    // Create an example hierarchy of tags.
-    // The family tree of Abraham is used as a well known example of a hierarchy (no statement intended).
-    // The order of ids is important because of: https://lab.civicrm.org/dev/core/-/issues/4049, that's why we create Isaac before Abraham.
-    CRM_Core_DAO::executeQuery("INSERT INTO civicrm_tag (id,name,used_for,is_tagset) VALUES(1, 'Isaac', 'civicrm_contact', 0);");
-    CRM_Core_DAO::executeQuery("INSERT INTO civicrm_tag (id,name,used_for,is_tagset) VALUES(2, 'Abraham', 'civicrm_contact', 0);");
-    CRM_Core_DAO::executeQuery("INSERT INTO civicrm_tag (id,name,used_for,is_tagset) VALUES(3, 'Jacob', 'civicrm_contact', 0);");
-    CRM_Core_DAO::executeQuery("INSERT INTO civicrm_tag (id,name,used_for,is_tagset) VALUES(4, 'Ishmael', 'civicrm_contact', 1);");
-    CRM_Core_DAO::executeQuery("INSERT INTO civicrm_tag (id,name,used_for,is_tagset) VALUES(5, 'Kedar', 'civicrm_contact', 1);");
-    CRM_Core_DAO::executeQuery("INSERT INTO civicrm_tag (id,name,used_for,is_tagset) VALUES(6, 'Working', 'civicrm_activity', 1);");
-    CRM_Core_DAO::executeQuery("INSERT INTO civicrm_tag (id,name,used_for,is_tagset) VALUES(7, 'Eating', 'civicrm_activity', 1);");
-
-    // Isaac is the son of abraham
-    CRM_Core_DAO::executeQuery("UPDATE civicrm_tag SET parent_id = 2 WHERE name = 'Isaac';");
-
-    // Jacob is the son of Isaac
-    CRM_Core_DAO::executeQuery("UPDATE civicrm_tag SET parent_id = 1 WHERE name = 'Jacob';");
-
-    // Ishmael is the son of abraham
-    CRM_Core_DAO::executeQuery("UPDATE civicrm_tag SET parent_id = 2 WHERE name = 'Ishmael';");
-
-    // Kedar is the son of Ishmael
-    CRM_Core_DAO::executeQuery("UPDATE civicrm_tag SET parent_id = 4 WHERE name = 'Kedar';");
-  }
-
-  /**
-   * Test that we can generate a correct tree of tags without suppliying additional filters.
-   *
-   * @throws \CRM_Core_Exception
-   */
-  public function testGetTreeWithoutFilters() {
-    $bao = new CRM_Core_BAO_Tag();
-
-    $tree = $bao->getTree();
-
-    $expected = [
-      2 => [
-        'parent_id' => NULL,
-        'name' => 'Abraham',
-        'description' => NULL,
-        'is_selectable' => '1',
-        'children' => [
-          1 => [
-            'parent_id' => '2',
-            'name' => 'Isaac',
-            'description' => NULL,
-            'is_selectable' => '1',
-            'children' => [
-              3 => [
-                'parent_id' => '1',
-                'name' => 'Jacob',
-                'description' => NULL,
-                'is_selectable' => '1',
-                'children' => [],
-              ],
-            ],
-          ],
-          4 => [
-            'parent_id' => '2',
-            'name' => 'Ishmael',
-            'is_selectable' => '1',
-            'description' => NULL,
-            'children' => [
-              5 => [
-                'parent_id' => '4',
-                'name' => 'Kedar',
-                'description' => NULL,
-                'is_selectable' => '1',
-                'children' => [],
-              ],
-            ],
-          ],
-        ],
-      ],
-      7 => [
-        'parent_id' => NULL,
-        'name' => 'Eating',
-        'description' => NULL,
-        'is_selectable' => '1',
-        'children' => [],
-      ],
-      6 => [
-        'parent_id' => NULL,
-        'name' => 'Working',
-        'description' => NULL,
-        'is_selectable' => '1',
-        'children' => [],
-      ],
-    ];
-
-    $this->assertEquals($expected, $tree);
-  }
-
-  /**
-   * Test that we can generate a correct tree of tags when using a usedFor filter and we're excluding hidden tags.
-   *
-   * @throws \CRM_Core_Exception
-   */
-  public function testGetTreeWithFilters() {
-    $bao = new CRM_Core_BAO_Tag();
-
-    $tree = $bao->getTree('civicrm_contact', TRUE);
-
-    $expected = [
-      2 => [
-        'parent_id' => NULL,
-        'name' => 'Abraham',
-        'description' => NULL,
-        'is_selectable' => '1',
-        'children' => [
-          1 => [
-            'parent_id' => '2',
-            'name' => 'Isaac',
-            'description' => NULL,
-            'is_selectable' => '1',
-            'children' => [
-              3 => [
-                'parent_id' => '1',
-                'name' => 'Jacob',
-                'description' => NULL,
-                'is_selectable' => '1',
-                'children' => [],
-              ],
-            ],
-          ],
-        ],
-      ],
-    ];
-
-    $this->assertEquals($expected, $tree);
-  }
-
-}
+<?php
+
+/**
+ * Class CRM_Core_BAO_TagTest
+ * @group headless
+ */
+class CRM_Core_BAO_TagTest extends CiviUnitTestCase {
+
+  /**
+   * Set up for class.
+   *
+   * @throws \CRM_Core_Exception
+   */
+  public function setUp(): void {
+    parent::setUp();
+    $this->quickCleanup(['civicrm_tag']);
+
+    // Create an example hierarchy of tags.
+    // The family tree of Abraham is used as a well known example of a hierarchy (no statement intended).
+    // The order of ids is important because of: https://lab.civicrm.org/dev/core/-/issues/4049, that's why we create Isaac before Abraham.
+    CRM_Core_DAO::executeQuery("INSERT INTO civicrm_tag (id,name,used_for,is_tagset) VALUES(1, 'Isaac', 'civicrm_contact', 0);");
+    CRM_Core_DAO::executeQuery("INSERT INTO civicrm_tag (id,name,used_for,is_tagset) VALUES(2, 'Abraham', 'civicrm_contact', 0);");
+    CRM_Core_DAO::executeQuery("INSERT INTO civicrm_tag (id,name,used_for,is_tagset) VALUES(3, 'Jacob', 'civicrm_contact', 0);");
+    CRM_Core_DAO::executeQuery("INSERT INTO civicrm_tag (id,name,used_for,is_tagset) VALUES(4, 'Ishmael', 'civicrm_contact', 1);");
+    CRM_Core_DAO::executeQuery("INSERT INTO civicrm_tag (id,name,used_for,is_tagset) VALUES(5, 'Kedar', 'civicrm_contact', 1);");
+    CRM_Core_DAO::executeQuery("INSERT INTO civicrm_tag (id,name,used_for,is_tagset) VALUES(6, 'Working', 'civicrm_activity', 1);");
+    CRM_Core_DAO::executeQuery("INSERT INTO civicrm_tag (id,name,used_for,is_tagset) VALUES(7, 'Eating', 'civicrm_activity', 1);");
+
+    // Isaac is the son of abraham
+    CRM_Core_DAO::executeQuery("UPDATE civicrm_tag SET parent_id = 2 WHERE name = 'Isaac';");
+
+    // Jacob is the son of Isaac
+    CRM_Core_DAO::executeQuery("UPDATE civicrm_tag SET parent_id = 1 WHERE name = 'Jacob';");
+
+    // Ishmael is the son of abraham
+    CRM_Core_DAO::executeQuery("UPDATE civicrm_tag SET parent_id = 2 WHERE name = 'Ishmael';");
+
+    // Kedar is the son of Ishmael
+    CRM_Core_DAO::executeQuery("UPDATE civicrm_tag SET parent_id = 4 WHERE name = 'Kedar';");
+  }
+
+  /**
+   * Test that we can generate a correct tree of tags without suppliying additional filters.
+   *
+   * @throws \CRM_Core_Exception
+   */
+  public function testGetTreeWithoutFilters(): void {
+    $bao = new CRM_Core_BAO_Tag();
+
+    $tree = $bao->getTree();
+
+    $expected = [
+      2 => [
+        'parent_id' => NULL,
+        'name' => 'Abraham',
+        'description' => NULL,
+        'is_selectable' => '1',
+        'children' => [
+          1 => [
+            'parent_id' => '2',
+            'name' => 'Isaac',
+            'description' => NULL,
+            'is_selectable' => '1',
+            'children' => [
+              3 => [
+                'parent_id' => '1',
+                'name' => 'Jacob',
+                'description' => NULL,
+                'is_selectable' => '1',
+                'children' => [],
+              ],
+            ],
+          ],
+          4 => [
+            'parent_id' => '2',
+            'name' => 'Ishmael',
+            'is_selectable' => '1',
+            'description' => NULL,
+            'children' => [
+              5 => [
+                'parent_id' => '4',
+                'name' => 'Kedar',
+                'description' => NULL,
+                'is_selectable' => '1',
+                'children' => [],
+              ],
+            ],
+          ],
+        ],
+      ],
+      7 => [
+        'parent_id' => NULL,
+        'name' => 'Eating',
+        'description' => NULL,
+        'is_selectable' => '1',
+        'children' => [],
+      ],
+      6 => [
+        'parent_id' => NULL,
+        'name' => 'Working',
+        'description' => NULL,
+        'is_selectable' => '1',
+        'children' => [],
+      ],
+    ];
+
+    $this->assertEquals($expected, $tree);
+  }
+
+  /**
+   * Test that we can generate a correct tree of tags when using a usedFor filter and we're excluding hidden tags.
+   *
+   * @throws \CRM_Core_Exception
+   */
+  public function testGetTreeWithFilters(): void {
+    $bao = new CRM_Core_BAO_Tag();
+
+    $tree = $bao->getTree('civicrm_contact', TRUE);
+
+    $expected = [
+      2 => [
+        'parent_id' => NULL,
+        'name' => 'Abraham',
+        'description' => NULL,
+        'is_selectable' => '1',
+        'children' => [
+          1 => [
+            'parent_id' => '2',
+            'name' => 'Isaac',
+            'description' => NULL,
+            'is_selectable' => '1',
+            'children' => [
+              3 => [
+                'parent_id' => '1',
+                'name' => 'Jacob',
+                'description' => NULL,
+                'is_selectable' => '1',
+                'children' => [],
+              ],
+            ],
+          ],
+        ],
+      ],
+    ];
+
+    $this->assertEquals($expected, $tree);
+  }
+
+}
diff --git a/tests/phpunit/CRM/Core/BAO/UFMatchTest.php b/tests/phpunit/CRM/Core/BAO/UFMatchTest.php
index e9916b8ebc15..c18da7fb46ea 100644
--- a/tests/phpunit/CRM/Core/BAO/UFMatchTest.php
+++ b/tests/phpunit/CRM/Core/BAO/UFMatchTest.php
@@ -9,7 +9,7 @@ class CRM_Core_BAO_UFMatchTest extends CiviUnitTestCase {
   /**
    * Don't crash if the uf_id doesn't exist
    */
-  public function testGetUFValuesWithNonexistentUFId() {
+  public function testGetUFValuesWithNonexistentUFId(): void {
     $max_id = (int) CRM_Core_DAO::singleValueQuery('SELECT MAX(uf_id) FROM civicrm_uf_match');
     $dontcrash = CRM_Core_BAO_UFMatch::getUFValues($max_id + 1);
     $this->assertNull($dontcrash);
diff --git a/tests/phpunit/CRM/Core/CodeGen/FreshnessTest.php b/tests/phpunit/CRM/Core/CodeGen/FreshnessTest.php
index 2cd67ff18823..dc269fc1d03d 100644
--- a/tests/phpunit/CRM/Core/CodeGen/FreshnessTest.php
+++ b/tests/phpunit/CRM/Core/CodeGen/FreshnessTest.php
@@ -9,7 +9,7 @@
  */
 class CRM_Core_CodeGen_FreshnessTest extends CiviUnitTestCase {
 
-  public function testDAOs() {
+  public function testDAOs(): void {
     $tasks = $this->findTasks('CRM_Core_CodeGen_DAO');
     $names = [];
     foreach ($tasks as $task) {
@@ -23,7 +23,7 @@ public function testDAOs() {
       'Expect the list of tables to include civicrm_contact');
   }
 
-  public function testReflection() {
+  public function testReflection(): void {
     $tasks = $this->findTasks('CRM_Core_CodeGen_Reflection');
     $this->assertEquals(1, count($tasks), 'Expect to find one Reflection task');
     foreach ($tasks as $task) {
diff --git a/tests/phpunit/CRM/Core/CommunityMessagesTest.php b/tests/phpunit/CRM/Core/CommunityMessagesTest.php
index 34104e7cb8ac..e396799602a3 100644
--- a/tests/phpunit/CRM/Core/CommunityMessagesTest.php
+++ b/tests/phpunit/CRM/Core/CommunityMessagesTest.php
@@ -151,7 +151,7 @@ public function badWebResponses() {
     return $result;
   }
 
-  public function testIsEnabled() {
+  public function testIsEnabled(): void {
     $communityMessages = new CRM_Core_CommunityMessages(
       $this->cache,
       $this->expectNoHttpRequest()
@@ -159,7 +159,7 @@ public function testIsEnabled() {
     $this->assertTrue($communityMessages->isEnabled());
   }
 
-  public function testIsEnabled_false() {
+  public function testIsEnabled_false(): void {
     $communityMessages = new CRM_Core_CommunityMessages(
       $this->cache,
       $this->expectNoHttpRequest(),
@@ -171,7 +171,7 @@ public function testIsEnabled_false() {
   /**
    * Download a document; after the set expiration period, download again.
    */
-  public function testGetDocument_NewOK_CacheOK_UpdateOK() {
+  public function testGetDocument_NewOK_CacheOK_UpdateOK(): void {
     // first try, good response
     CRM_Utils_Time::setTime('2013-03-01 10:00:00');
     $communityMessages = new CRM_Core_CommunityMessages(
@@ -306,7 +306,7 @@ public function testGetDocument_NewOK_UpdateFailure_CacheOK_UpdateOK($badWebResp
   /**
    * Randomly pick among two options.
    */
-  public function testPick_rand() {
+  public function testPick_rand(): void {
     $communityMessages = new CRM_Core_CommunityMessages(
       $this->cache,
       $this->expectOneHttpRequest(self::$webResponses['two-messages'])
@@ -334,7 +334,7 @@ public function testPick_rand() {
    * When presented with two options using component filters, always
    * choose the one which references an active component.
    */
-  public function testPick_componentFilter() {
+  public function testPick_componentFilter(): void {
     $communityMessages = new CRM_Core_CommunityMessages(
       $this->cache,
       $this->expectOneHttpRequest(self::$webResponses['two-messages-halfbadcomp'])
@@ -355,7 +355,7 @@ public function testPick_componentFilter() {
     $this->assertEquals($trials, $freq['<h1>Two</h1>']);
   }
 
-  public function testEvalMarkup() {
+  public function testEvalMarkup(): void {
     $communityMessages = new CRM_Core_CommunityMessages(
       $this->cache,
       $this->expectNoHttpRequest()
diff --git a/tests/phpunit/CRM/Core/ComposerConfigTest.php b/tests/phpunit/CRM/Core/ComposerConfigTest.php
index f6e22ba58ff7..1d68fdf2ddbd 100644
--- a/tests/phpunit/CRM/Core/ComposerConfigTest.php
+++ b/tests/phpunit/CRM/Core/ComposerConfigTest.php
@@ -19,7 +19,7 @@ class CRM_Core_ComposerConfigTest extends \PHPUnit\Framework\TestCase {
    * `composer.lock`, and no one would notice the change in policy
    * because reviewers' eyes tend to gloss over `composer.lock`.
    */
-  public function testHardLocks() {
+  public function testHardLocks(): void {
     $hardLocks = [
       'symfony/config' => '/^v4\.4\./',
       'symfony/dependency-injection' => '/^v4\.4\./',
diff --git a/tests/phpunit/CRM/Core/Config/MailerTest.php b/tests/phpunit/CRM/Core/Config/MailerTest.php
index 9f24e4ae326e..86fbdd258993 100644
--- a/tests/phpunit/CRM/Core/Config/MailerTest.php
+++ b/tests/phpunit/CRM/Core/Config/MailerTest.php
@@ -38,7 +38,7 @@ public function setUp(): void {
     parent::setUp();
   }
 
-  public function testHookAlterMailer() {
+  public function testHookAlterMailer(): void {
     $test = $this;
     $mockMailer = new CRM_Utils_FakeObject([
       'send' => function ($recipients, $headers, $body) use ($test) {
diff --git a/tests/phpunit/CRM/Core/CopyTest.php b/tests/phpunit/CRM/Core/CopyTest.php
index 6881796f0ef0..dad899768434 100644
--- a/tests/phpunit/CRM/Core/CopyTest.php
+++ b/tests/phpunit/CRM/Core/CopyTest.php
@@ -66,7 +66,7 @@ public function testEventCopy(): void {
   /**
    * @group locale
    */
-  public function testI18nEventCopy() {
+  public function testI18nEventCopy(): void {
 
     $locales = ['en_US', 'fr_CA', 'nl_NL'];
 
diff --git a/tests/phpunit/CRM/Core/DAO/AllCoreTablesTest.php b/tests/phpunit/CRM/Core/DAO/AllCoreTablesTest.php
index cc66c601bf90..12c8f9ee23c3 100644
--- a/tests/phpunit/CRM/Core/DAO/AllCoreTablesTest.php
+++ b/tests/phpunit/CRM/Core/DAO/AllCoreTablesTest.php
@@ -6,7 +6,7 @@
  */
 class CRM_Core_DAO_AllCoreTablesTest extends CiviUnitTestCase {
 
-  public function testGetTableForClass() {
+  public function testGetTableForClass(): void {
     $this->assertEquals('civicrm_email', CRM_Core_DAO_AllCoreTables::getTableForClass('CRM_Core_DAO_Email'));
     $this->assertEquals('civicrm_email', CRM_Core_DAO_AllCoreTables::getTableForClass('CRM_Core_BAO_Email'));
   }
@@ -15,7 +15,7 @@ public function testGetTableForClass() {
    * Ensure that hook_civicrm_entityTypes runs and correctly handles the
    * 'fields_callback' option.
    */
-  public function testHook() {
+  public function testHook(): void {
     // 1. First, check the baseline fields()...
     $fields = CRM_Core_DAO_Email::fields();
     $this->assertFalse(isset($fields['location_type_id']['foo']));
@@ -61,7 +61,7 @@ protected function tearDown(): void {
    *
    * @group locale
    */
-  public function testIndices() {
+  public function testIndices(): void {
     // civicrm_group UI_title is localizable
     // Check indices without localization
     $indices = CRM_Core_DAO_AllCoreTables::indices(FALSE);
@@ -86,7 +86,7 @@ public function testIndices() {
   /**
    * Check CRM_Core_DAO_AllCoreTables::multilingualize()
    */
-  public function testMultilingualize() {
+  public function testMultilingualize(): void {
     // in civicrm_group, title is localizable, name is not
     $originalIndices = [
       'test_index1' => [
@@ -210,23 +210,23 @@ public function testMultilingualize() {
   /**
    * Test CRM_Core_DAO_AllCoreTables::isCoreTable
    */
-  public function testIsCoreTable() {
+  public function testIsCoreTable(): void {
     $this->assertTrue(CRM_Core_DAO_AllCoreTables::isCoreTable('civicrm_contact'), 'civicrm_contact should be a core table');
     $this->assertFalse(CRM_Core_DAO_AllCoreTables::isCoreTable('civicrm_invalid_table'), 'civicrm_invalid_table should NOT be a core table');
   }
 
-  public function testGetBriefName() {
+  public function testGetBriefName(): void {
     $this->assertEquals('Contact', CRM_Core_DAO_AllCoreTables::getBriefName('CRM_Contact_BAO_Contact'));
     $this->assertEquals('Contact', CRM_Core_DAO_AllCoreTables::getBriefName('CRM_Contact_DAO_Contact'));
     $this->assertNull(CRM_Core_DAO_AllCoreTables::getBriefName('CRM_Core_DAO_XqZy'));
   }
 
-  public function testGetFullName() {
+  public function testGetFullName(): void {
     $this->assertEquals('CRM_Contact_DAO_Contact', CRM_Core_DAO_AllCoreTables::getFullName('Contact'));
     $this->assertNull(CRM_Core_DAO_AllCoreTables::getFullName('XqZy'));
   }
 
-  public function testGetEntityNameForTable() {
+  public function testGetEntityNameForTable(): void {
     $this->assertEquals('Contact', CRM_Core_DAO_AllCoreTables::getEntityNameForTable('civicrm_contact'));
     $this->assertEquals('RelationshipCache', CRM_Core_DAO_AllCoreTables::getEntityNameForTable('civicrm_relationship_cache'));
     $this->assertNull(CRM_Core_DAO_AllCoreTables::getEntityNameForTable('civicrm_invalid_table'));
diff --git a/tests/phpunit/CRM/Core/DAOConformanceTest.php b/tests/phpunit/CRM/Core/DAOConformanceTest.php
index a89af22d8931..fa49907edfc4 100644
--- a/tests/phpunit/CRM/Core/DAOConformanceTest.php
+++ b/tests/phpunit/CRM/Core/DAOConformanceTest.php
@@ -10,7 +10,7 @@ class CRM_Core_DAOConformanceTest extends CiviUnitTestCase {
   /**
    * Check all fields have defined titles.
    */
-  public function testFieldsHaveTitles() {
+  public function testFieldsHaveTitles(): void {
     foreach (CRM_Core_DAO_AllCoreTables::getClasses() as $class) {
       $dao = new $class();
       $fields = $dao->fields();
diff --git a/tests/phpunit/CRM/Core/DAOTest.php b/tests/phpunit/CRM/Core/DAOTest.php
index ea4c58285d79..5dbdcd8632b9 100644
--- a/tests/phpunit/CRM/Core/DAOTest.php
+++ b/tests/phpunit/CRM/Core/DAOTest.php
@@ -8,7 +8,7 @@ class CRM_Core_DAOTest extends CiviUnitTestCase {
 
   const ABORTED_SQL = "_aborted_sql_";
 
-  public function testGetReferenceColumns() {
+  public function testGetReferenceColumns(): void {
     // choose CRM_Core_DAO_Email as an arbitrary example
     $emailRefs = CRM_Core_DAO_Email::getReferenceColumns();
     $refsByTarget = [];
@@ -22,7 +22,7 @@ public function testGetReferenceColumns() {
     $this->assertInstanceOf(\CRM_Core_Reference_Basic::class, $contactRef);
   }
 
-  public function testGetReferencesToTable() {
+  public function testGetReferencesToTable(): void {
     $refs = CRM_Core_DAO::getReferencesToTable(CRM_Financial_DAO_FinancialType::getTableName());
     $refsBySource = [];
     foreach ($refs as $refSpec) {
@@ -36,7 +36,7 @@ public function testGetReferencesToTable() {
     $this->assertEquals('CRM_Core_Reference_Dynamic', get_class($genericRef));
   }
 
-  public function testFindReferences() {
+  public function testFindReferences(): void {
     $params = [
       'first_name' => 'Testy',
       'last_name' => 'McScallion',
@@ -183,7 +183,7 @@ public function testComposeQuery($inputSql, $inputParams, $expectSql) {
    * $params[3] = array('Bob', 'String');
    * i.e. the place holder should be unique and should not contain in any other operational use in query
    */
-  public function testComposeQueryFailure() {
+  public function testComposeQueryFailure(): void {
     $cases[] = [
       'SELECT * FROM whatever WHERE name = %1 AND title = %2 AND year LIKE \'%2012\' ',
       [
@@ -242,7 +242,7 @@ public function testShortenSQLName($inputData, $length, $makeRandom, $expectedRe
     $this->assertEquals($expectedResult, CRM_Core_DAO::shortenSQLName($inputData, $length, $makeRandom));
   }
 
-  public function testFindById() {
+  public function testFindById(): void {
     $params = $this->sampleContact('Individual', 4);
     $existing_contact = $this->callAPISuccess('Contact', 'create', $params);
     /** @var CRM_Contact_DAO_Contact $contact */
@@ -263,7 +263,7 @@ public function testFindById() {
   /**
    * requireSafeDBName() method (to check valid database name)
    */
-  public function testRequireSafeDBName() {
+  public function testRequireSafeDBName(): void {
     $databases = [
       'testdb' => TRUE,
       'test_db' => TRUE,
@@ -287,7 +287,7 @@ public function testRequireSafeDBName() {
   /**
    * Test the function designed to find myIsam tables.
    */
-  public function testMyISAMCheck() {
+  public function testMyISAMCheck(): void {
     // Cleanup previous, failed tests.
     CRM_Core_DAO::executeQuery('DROP TABLE IF EXISTS civicrm_my_isam');
 
@@ -310,7 +310,7 @@ public function testMyISAMCheck() {
   /**
    * CRM-19930: Test toArray() function with $format param
    */
-  public function testDAOtoArray() {
+  public function testDAOtoArray(): void {
     $format = 'user[%s]';
     $params = [
       'first_name' => 'Testy',
@@ -341,7 +341,7 @@ public function testDAOtoArray() {
   /**
    * CRM-17748: Test internal DAO options
    */
-  public function testDBOptions() {
+  public function testDBOptions(): void {
     $contactIDs = [];
     for ($i = 0; $i < 10; $i++) {
       $contactIDs[] = $this->individualCreate([
@@ -377,7 +377,7 @@ public function _testMemoryUsageForUnbufferedQuery() {
   /**
    * Test that known sql modes are present in session.
    */
-  public function testSqlModePresent() {
+  public function testSqlModePresent(): void {
     $sqlModes = CRM_Utils_SQL::getSqlModes();
     // assert we have strict trans
     $this->assertContains('STRICT_TRANS_TABLES', $sqlModes);
@@ -420,7 +420,7 @@ public function serializationMethods() {
     return $constants;
   }
 
-  public function testFetchGeneratorDao() {
+  public function testFetchGeneratorDao(): void {
     $this->individualCreate([], 0);
     $this->individualCreate([], 1);
     $this->individualCreate([], 2);
@@ -434,7 +434,7 @@ public function testFetchGeneratorDao() {
     $this->assertEquals(3, $count);
   }
 
-  public function testFetchGeneratorArray() {
+  public function testFetchGeneratorArray(): void {
     $this->individualCreate([], 0);
     $this->individualCreate([], 1);
     $this->individualCreate([], 2);
@@ -462,7 +462,7 @@ public function testFieldSerialization($method, $sampleData) {
   /**
    * Test the DAO cloning method does not hit issues with freeing the result.
    */
-  public function testCloneDAO() {
+  public function testCloneDAO(): void {
     $dao = CRM_Core_DAO::executeQuery('SELECT * FROM civicrm_domain');
     $i = 0;
     while ($dao->fetch()) {
@@ -480,7 +480,7 @@ public function testCloneDAO() {
    *
    * @throws \Exception
    */
-  public function testModifyQuery() {
+  public function testModifyQuery(): void {
     /**
      * @param \Civi\Core\Event\QueryEvent $e
      */
@@ -498,7 +498,7 @@ public function testModifyQuery() {
    *
    * Demonstrate it is modified showing the query now breaks.
    */
-  public function testModifyAndBreakQuery() {
+  public function testModifyAndBreakQuery(): void {
     $dbNameString = stripos(CRM_Utils_SQL::getDatabaseVersion(), 'mariadb') !== FALSE ? 'MariaDB' : 'MySQL';
     /**
      * @param \Civi\Core\Event\QueryEvent $e
@@ -522,7 +522,7 @@ public function testModifyAndBreakQuery() {
     $this->fail('String not altered');
   }
 
-  public function testSupportedFields() {
+  public function testSupportedFields(): void {
     // Hack a different db version which will trigger getSupportedFields to filter out newer fields
     CRM_Core_BAO_Domain::getDomain()->version = '5.26.0';
 
@@ -548,7 +548,7 @@ public function testSupportedFields() {
     $this->assertArrayNotHasKey('api_key', $permissionedContactFields);
   }
 
-  public function testTableHasBeenAdded() {
+  public function testTableHasBeenAdded(): void {
     // Hack a different db version
     CRM_Core_BAO_Domain::getDomain()->version = '5.28.0';
 
@@ -568,7 +568,7 @@ public function testTableHasBeenAdded() {
    *
    * @throws CRM_Core_Exception
    */
-  public function testUpdateTimestampWithBlankDate() {
+  public function testUpdateTimestampWithBlankDate(): void {
     // Arbitrarily using "Cache" since it has a desired type of timestamp field and is simple.
     $dao = new CRM_Core_DAO_Cache();
     $fields = $dao->fields();
@@ -602,7 +602,7 @@ public function testUpdateTimestampWithBlankDate() {
     $this->assertNull($dao->expired_date);
   }
 
-  public function testFillValues() {
+  public function testFillValues(): void {
     $label = uniqid();
     $saved = CRM_Contact_BAO_SavedSearch::writeRecord([
       'label' => $label,
diff --git a/tests/phpunit/CRM/Core/FieldOptionsTest.php b/tests/phpunit/CRM/Core/FieldOptionsTest.php
index 32b80f46fbfc..826ba3bddb67 100644
--- a/tests/phpunit/CRM/Core/FieldOptionsTest.php
+++ b/tests/phpunit/CRM/Core/FieldOptionsTest.php
@@ -44,7 +44,7 @@ public function tearDown(): void {
    * Assure CRM_Core_PseudoConstant::get() is working properly for a range of
    * DAO fields having a <pseudoconstant> tag in the XML schema.
    */
-  public function testOptionValues() {
+  public function testOptionValues(): void {
     /**
      * baoName/field combinations to test
      * Format: array[BAO Name] = $properties, where properties is an array whose
@@ -101,7 +101,7 @@ public function testOptionValues() {
   /**
    * Ensure hook_civicrm_fieldOptions is working
    */
-  public function testHookFieldOptions() {
+  public function testHookFieldOptions(): void {
     CRM_Core_PseudoConstant::flush();
 
     // Test replacing all options with a hook
@@ -126,7 +126,7 @@ public function testHookFieldOptions() {
   /**
    * Ensure hook_civicrm_fieldOptions works with custom fields
    */
-  public function testHookFieldOptionsWithCustomFields() {
+  public function testHookFieldOptionsWithCustomFields(): void {
     // Create a custom field group for testing.
     $custom_group_name = md5(microtime());
     $api_params = [
diff --git a/tests/phpunit/CRM/Core/I18n/LocaleTest.php b/tests/phpunit/CRM/Core/I18n/LocaleTest.php
index 47f6cd7bff47..6189141b9332 100644
--- a/tests/phpunit/CRM/Core/I18n/LocaleTest.php
+++ b/tests/phpunit/CRM/Core/I18n/LocaleTest.php
@@ -18,7 +18,7 @@ class CRM_Core_I18n_LocaleTest extends CiviUnitTestCase {
   /**
    *
    */
-  public function testI18nLocaleChange() {
+  public function testI18nLocaleChange(): void {
     $cleanup = $this->useMultilingual(['en_US' => 'fr_CA']);
 
     CRM_Core_I18n::singleton()->setLocale('fr_CA');
@@ -26,7 +26,7 @@ public function testI18nLocaleChange() {
     $this->assertEquals('fr_CA', $locale);
   }
 
-  public function testUiLanguages() {
+  public function testUiLanguages(): void {
     $languages = [
       'en_US' => 'English (United States)',
       'fr_CA' => 'French (Canada)',
@@ -139,7 +139,7 @@ public function testPartialLocale(array $settings, string $preferred, array $exp
   /**
    * Quirk in strtolower does not handle "I" as expected, compared to mb_strtolower.
    */
-  public function testInsertTurkish() {
+  public function testInsertTurkish(): void {
     CRM_Core_DAO::executeQuery("DROP TABLE IF EXISTS foo");
     CRM_Core_DAO::executeQuery("CREATE TABLE foo ( bar varchar(32) )");
     // Change locale - assert it actually changed.
diff --git a/tests/phpunit/CRM/Core/I18n/SchemaTest.php b/tests/phpunit/CRM/Core/I18n/SchemaTest.php
index daaa49a93784..46532063472d 100644
--- a/tests/phpunit/CRM/Core/I18n/SchemaTest.php
+++ b/tests/phpunit/CRM/Core/I18n/SchemaTest.php
@@ -105,7 +105,7 @@ public function testI18nSchemaRewrite($table, $expectedRewrite) {
     }
   }
 
-  public function testSchemaBuild() {
+  public function testSchemaBuild(): void {
     $this->enableMultilingual();
     $inUseCollation = CRM_Core_BAO_SchemaHandler::getInUseCollation();
     $testCreateTable = CRM_Core_DAO::executeQuery("show create table civicrm_price_set", [], TRUE, NULL, FALSE, FALSE);
@@ -115,7 +115,7 @@ public function testSchemaBuild() {
     }
   }
 
-  public function testMultilingualCustomFieldCreation() {
+  public function testMultilingualCustomFieldCreation(): void {
     $this->enableMultilingual(['en_US' => 'fr_CA']);
     $id = $this->customGroupCreate()['id'];
     $this->customFieldCreate(['custom_group_id' => $id]);
diff --git a/tests/phpunit/CRM/Core/JobManagerTest.php b/tests/phpunit/CRM/Core/JobManagerTest.php
index d8f910e836a5..4f28bb47634a 100644
--- a/tests/phpunit/CRM/Core/JobManagerTest.php
+++ b/tests/phpunit/CRM/Core/JobManagerTest.php
@@ -15,7 +15,7 @@
  */
 class CRM_Core_JobManagerTest extends CiviUnitTestCase {
 
-  public function testHookCron() {
+  public function testHookCron(): void {
     $hook = $this->getMockBuilder(stdClass::class)
       ->setMethods(['civicrm_cron'])
       ->getMock();
diff --git a/tests/phpunit/CRM/Core/KeyTest.php b/tests/phpunit/CRM/Core/KeyTest.php
index 66e95042a2c4..89ebbdfb7bf5 100644
--- a/tests/phpunit/CRM/Core/KeyTest.php
+++ b/tests/phpunit/CRM/Core/KeyTest.php
@@ -15,19 +15,19 @@
  */
 class CRM_Core_KeyTest extends CiviUnitTestCase {
 
-  public function testOK() {
+  public function testOK(): void {
     $key = CRM_Core_Key::get('CRM_Bread_Butter');
     $this->assertTrue(CRM_Core_Key::valid($key));
     $this->assertEquals($key, CRM_Core_Key::validate($key, 'CRM_Bread_Butter'));
   }
 
-  public function testMalformed() {
+  public function testMalformed(): void {
     $key = CRM_Core_Key::get('CRM_Bread_Butter') . '<script>';
     $this->assertFalse(CRM_Core_Key::valid($key));
     $this->assertEquals(NULL, CRM_Core_Key::validate($key, 'CRM_Bread_Butter'));
   }
 
-  public function testMixedUp() {
+  public function testMixedUp(): void {
     $key = CRM_Core_Key::get('CRM_Toast_Jam');
     $this->assertTrue(CRM_Core_Key::valid($key));
     $this->assertEquals(NULL, CRM_Core_Key::validate($key, 'CRM_Bread_Butter'));
diff --git a/tests/phpunit/CRM/Core/ManagedEntitiesTest.php b/tests/phpunit/CRM/Core/ManagedEntitiesTest.php
index d2bdbd81ae0d..43876a6b0bc2 100644
--- a/tests/phpunit/CRM/Core/ManagedEntitiesTest.php
+++ b/tests/phpunit/CRM/Core/ManagedEntitiesTest.php
@@ -175,7 +175,7 @@ private function getManagedEntity(string $moduleName, string $managedName):? arr
    * to (1) create 'foo' entity, (2) create 'bar' entity', (3) remove 'foo'
    * entity
    */
-  public function testAddRemoveEntitiesModule_UpdateAlways_DeleteAlways() {
+  public function testAddRemoveEntitiesModule_UpdateAlways_DeleteAlways(): void {
     // create first managed entity ('foo')
     $this->managedEntities = [$this->fixtures['com.example.one-foo']];
     $me = new CRM_Core_ManagedEntities($this->modules);
@@ -627,7 +627,7 @@ public function testDependentEntitiesUninstallCleanly(): void {
    * Pre-existing implementations may over-report (ie return entities despite the `$modules` filter).
    * This test ensures that the framework respects the `$modules` filter (even if specific implementations don't).
    */
-  public function testHookManaged_FilterModule() {
+  public function testHookManaged_FilterModule(): void {
     $this->managedEntities = [
       $this->fixtures['com.example.one-bar'],
       $this->fixtures['com.example.two-CustomGroup'],
diff --git a/tests/phpunit/CRM/Core/MenuTest.php b/tests/phpunit/CRM/Core/MenuTest.php
index a01842077648..f8677603a8c6 100644
--- a/tests/phpunit/CRM/Core/MenuTest.php
+++ b/tests/phpunit/CRM/Core/MenuTest.php
@@ -6,7 +6,7 @@
  */
 class CRM_Core_MenuTest extends CiviUnitTestCase {
 
-  public function testReadXML() {
+  public function testReadXML(): void {
     $xmlString = '<?xml version="1.0" encoding="iso-8859-1" ?>
     <menu>
       <item>
@@ -31,7 +31,7 @@ public function testReadXML() {
     $this->assertTrue(!isset($menu['civicrm/foo/bar']['ids_arguments']));
   }
 
-  public function testReadXML_IDS() {
+  public function testReadXML_IDS(): void {
     $xmlString = '<?xml version="1.0" encoding="iso-8859-1" ?>
     <menu>
       <item>
@@ -69,7 +69,7 @@ public function testReadXML_IDS() {
    * Check that novel data elements in the menu are correctly
    * stored and loaded.
    */
-  public function testModuleData() {
+  public function testModuleData(): void {
     CRM_Core_Menu::store(TRUE);
     $item = CRM_Core_Menu::get('civicrm/case');
     $this->assertFalse(isset($item['ids_arguments']['exceptions']));
diff --git a/tests/phpunit/CRM/Core/OptionGroupTest.php b/tests/phpunit/CRM/Core/OptionGroupTest.php
index 5c3295b62642..2b50d1b960eb 100644
--- a/tests/phpunit/CRM/Core/OptionGroupTest.php
+++ b/tests/phpunit/CRM/Core/OptionGroupTest.php
@@ -25,7 +25,7 @@ public function setUp(): void {
   /**
    * Ensure only one option value exists after calling ensureOptionValueExists.
    */
-  public function testWeightOptionGroup() {
+  public function testWeightOptionGroup(): void {
     $values = [];
     $options1 = CRM_Core_OptionGroup::values('activity_type', FALSE, FALSE, FALSE, NULL, 'label', FALSE);
     $options2 = CRM_Core_OptionGroup::values('activity_type', FALSE, FALSE, FALSE, NULL, 'label', FALSE, FALSE, 'value', 'name');
@@ -91,7 +91,7 @@ public function testSanitizeFromEmailAddress($dirty, $clean) {
     $this->assertEquals($actual, $clean);
   }
 
-  public function testDomainSpecificValueCache() {
+  public function testDomainSpecificValueCache(): void {
     $original_domain = \CRM_Core_Config::domainID();
     $domainIDs = [];
     $optionValues = [];
diff --git a/tests/phpunit/CRM/Core/Page/AJAXTest.php b/tests/phpunit/CRM/Core/Page/AJAXTest.php
index 6855a6dbf977..7bc2dab62f57 100644
--- a/tests/phpunit/CRM/Core/Page/AJAXTest.php
+++ b/tests/phpunit/CRM/Core/Page/AJAXTest.php
@@ -6,7 +6,7 @@
  */
 class CRM_Core_Page_AJAXTest extends CiviUnitTestCase {
 
-  public function testCheckAuthz() {
+  public function testCheckAuthz(): void {
     $cases = [];
 
     $cases[] = ['method', 'CRM_Foo', FALSE, 'method'];
diff --git a/tests/phpunit/CRM/Core/Page/HookTest.php b/tests/phpunit/CRM/Core/Page/HookTest.php
index aee9f327cba5..d34886efd0dc 100644
--- a/tests/phpunit/CRM/Core/Page/HookTest.php
+++ b/tests/phpunit/CRM/Core/Page/HookTest.php
@@ -133,7 +133,7 @@ private function runTestAssert($pageName) {
   /**
    * Make sure pageRun hook is only invoked once.
    */
-  public function testPagesCallPageRunOnce() {
+  public function testPagesCallPageRunOnce(): void {
     CRM_Utils_Hook_UnitTests::singleton()->setHook('civicrm_pageRun', [$this, 'onPageRun']);
     $_REQUEST = ['action' => 'browse'];
     foreach ($this->basicPages as $pageName) {
diff --git a/tests/phpunit/CRM/Core/Payment/AuthorizeNetTest.php b/tests/phpunit/CRM/Core/Payment/AuthorizeNetTest.php
index faf935b2c25a..86763601cbc3 100644
--- a/tests/phpunit/CRM/Core/Payment/AuthorizeNetTest.php
+++ b/tests/phpunit/CRM/Core/Payment/AuthorizeNetTest.php
@@ -46,7 +46,7 @@ public function tearDown(): void {
    * @throws \Civi\Payment\Exception\PaymentProcessorException
    * @throws \CRM_Core_Exception
    */
-  public function testSinglePayment() {
+  public function testSinglePayment(): void {
     $this->setupMockHandler();
     $params = $this->getBillingParams();
     $params['amount'] = 5.24;
@@ -59,7 +59,7 @@ public function testSinglePayment() {
    *
    * Test works but not both due to some form of caching going on in the SmartySingleton
    */
-  public function testCreateSingleNowDated() {
+  public function testCreateSingleNowDated(): void {
     $this->isRecur = TRUE;
     $this->setupMockHandler();
     $firstName = 'John';
@@ -181,7 +181,7 @@ public function testCreateSingleNowDated() {
   /**
    * Create a single post dated payment as a recurring transaction.
    */
-  public function testCreateSinglePostDated() {
+  public function testCreateSinglePostDated(): void {
     $this->isRecur = TRUE;
     $this->setupMockHandler();
     $start_date = date('Ymd', strtotime('+ 1 week'));
@@ -400,7 +400,7 @@ protected function getBillingParams(): array {
   /**
    * Test the update billing function.
    */
-  public function testUpdateBilling() {
+  public function testUpdateBilling(): void {
     $this->setUpClient($this->getExpectedUpdateResponse());
     $params = [
       'qfKey' => '52e3078a34158a80b18d0e3c690c5b9f_2369',
@@ -437,7 +437,7 @@ public function testUpdateBilling() {
    *
    * @throws \Civi\Payment\Exception\PaymentProcessorException
    */
-  public function testChangeSubscription() {
+  public function testChangeSubscription(): void {
     $this->setUpClient($this->getExpectedUpdateResponse());
     $params = [
       'hidden_custom' => '1',
@@ -579,7 +579,7 @@ protected function setUpClient($response) {
   /**
    * @throws \Civi\Payment\Exception\PaymentProcessorException
    */
-  public function testCancelRecurring() {
+  public function testCancelRecurring(): void {
     $this->setUpClient($this->getExpectedCancelResponse());
     $propertyBag = new PropertyBag();
     $propertyBag->setContributionRecurID(9);
diff --git a/tests/phpunit/CRM/Core/Payment/PaypalProTest.php b/tests/phpunit/CRM/Core/Payment/PaypalProTest.php
index 94dbc7663bf9..6cd7ceac6e2a 100644
--- a/tests/phpunit/CRM/Core/Payment/PaypalProTest.php
+++ b/tests/phpunit/CRM/Core/Payment/PaypalProTest.php
@@ -39,7 +39,7 @@ public function tearDown(): void {
    * @throws \Civi\Payment\Exception\PaymentProcessorException
    * @throws \CRM_Core_Exception
    */
-  public function testSinglePayment() {
+  public function testSinglePayment(): void {
     $this->setupMockHandler();
     $params = $this->getBillingParams();
     $params['amount'] = 5.24;
diff --git a/tests/phpunit/CRM/Core/Payment/PaypalStdTest.php b/tests/phpunit/CRM/Core/Payment/PaypalStdTest.php
index 214e815a180f..c95fc0d38ca8 100644
--- a/tests/phpunit/CRM/Core/Payment/PaypalStdTest.php
+++ b/tests/phpunit/CRM/Core/Payment/PaypalStdTest.php
@@ -50,7 +50,7 @@ public function tearDown(): void {
    *
    * @throws \Civi\Payment\Exception\PaymentProcessorException
    */
-  public function testSinglePayment() {
+  public function testSinglePayment(): void {
     $params = [];
     $params['amount'] = 5.24;
     $params['currency'] = 'USD';
diff --git a/tests/phpunit/CRM/Core/Payment/ProcessorFormTest.php b/tests/phpunit/CRM/Core/Payment/ProcessorFormTest.php
index 680b62fd8596..d358f271679c 100644
--- a/tests/phpunit/CRM/Core/Payment/ProcessorFormTest.php
+++ b/tests/phpunit/CRM/Core/Payment/ProcessorFormTest.php
@@ -228,7 +228,7 @@ public function testPaymentProcessorWithStandardBillingRequirements(): void {
    * Checks that, if the payment processor doesn't declare a field
    * as needed, the field shouldn't be considered mandatory.
    */
-  public function testPaymentProcessorWithCustomRequirements() {
+  public function testPaymentProcessorWithCustomRequirements(): void {
     $canBeHiddenWithTheCustomProfile = $this->checkPaymentProcessorWithProfile(
       "PaymentProcessorWithCustomBillingRequirements",
       "custom"
diff --git a/tests/phpunit/CRM/Core/PaymentTest.php b/tests/phpunit/CRM/Core/PaymentTest.php
index 3615719a072a..d5de27f55c65 100644
--- a/tests/phpunit/CRM/Core/PaymentTest.php
+++ b/tests/phpunit/CRM/Core/PaymentTest.php
@@ -20,7 +20,7 @@ class CRM_Core_PaymentTest extends CiviUnitTestCase {
   /**
    * Test the payment method is adequately logged - we don't expect the processing to succeed
    */
-  public function testHandlePaymentMethodLogging() {
+  public function testHandlePaymentMethodLogging(): void {
     $params = ['processor_name' => 'Paypal', 'data' => 'blah'];
     try {
       CRM_Core_Payment::handlePaymentMethod('method', $params);
@@ -35,7 +35,7 @@ public function testHandlePaymentMethodLogging() {
   /**
    * Test that CVV is always required for front facing pages.
    */
-  public function testCVVSettingForContributionPages() {
+  public function testCVVSettingForContributionPages(): void {
     Civi::settings()->set('cvv_backoffice_required', 0);
     $processor = NULL;
     $dummyPayment = new CRM_Core_Payment_Dummy("test", $processor);
@@ -58,7 +58,7 @@ public function testCVVSettingForContributionPages() {
     $this->assertEquals(1, $paymentMetaData["cvv2"]["is_required"], "CVV should always be required for front office.");
   }
 
-  public function testSettingUrl() {
+  public function testSettingUrl(): void {
     /** @var CRM_Core_Payment_Dummy $processor */
     $processor = \Civi\Payment\System::singleton()->getById($this->processorCreate());
     $success = 'http://success.com';
diff --git a/tests/phpunit/CRM/Core/PseudoConstantTest.php b/tests/phpunit/CRM/Core/PseudoConstantTest.php
index 3f3768db3d6b..af22edd07448 100644
--- a/tests/phpunit/CRM/Core/PseudoConstantTest.php
+++ b/tests/phpunit/CRM/Core/PseudoConstantTest.php
@@ -28,7 +28,7 @@ public function setUp(): void {
    * Assure CRM_Core_PseudoConstant::get() is working properly for a range of
    * DAO fields having a <pseudoconstant> tag in the XML schema.
    */
-  public function testOptionValues() {
+  public function testOptionValues(): void {
 
     // Create a custom field group for testing.
     $custom_group_name = md5(microtime());
@@ -975,7 +975,7 @@ public function testOptionValues() {
     }
   }
 
-  public function testContactTypes() {
+  public function testContactTypes(): void {
     $byName = [
       'Individual' => 'Individual',
       'Household' => 'Household',
@@ -1004,7 +1004,7 @@ public function testContactTypes() {
     $this->assertEquals(array_flip($byId), $result);
   }
 
-  public function testGetTaxRates() {
+  public function testGetTaxRates(): void {
     $contact = $this->createLoggedInUser();
     $financialType = $this->callAPISuccess('financial_type', 'create', [
       'name' => 'Test taxable financial Type',
diff --git a/tests/phpunit/CRM/Core/RegionTest.php b/tests/phpunit/CRM/Core/RegionTest.php
index e46f6f5c1aa0..e25a1986eb71 100644
--- a/tests/phpunit/CRM/Core/RegionTest.php
+++ b/tests/phpunit/CRM/Core/RegionTest.php
@@ -40,7 +40,7 @@ public function createEmptyCollection() {
    * When a {crmRegion} is blank and when there are no extra snippets, the
    * output is blank.
    */
-  public function testBlank() {
+  public function testBlank(): void {
     $smarty = CRM_Core_Smarty::singleton();
     $actual = $smarty->fetch('string:{crmRegion name=testBlank}{/crmRegion}');
     $expected = '';
@@ -51,7 +51,7 @@ public function testBlank() {
    * When a {crmRegion} is not blank and when there are no extra snippets,
    * the output is only determined by the {crmRegion} block.
    */
-  public function testDefault() {
+  public function testDefault(): void {
     $smarty = CRM_Core_Smarty::singleton();
     $actual = $smarty->fetch('string:{crmRegion name=testDefault}default<br/>{/crmRegion}');
     $expected = 'default<br/>';
@@ -61,7 +61,7 @@ public function testDefault() {
   /**
    * Disable the normal content of a {crmRegion} and apply different content from a snippet
    */
-  public function testOverride() {
+  public function testOverride(): void {
     CRM_Core_Region::instance('testOverride')->update('default', [
       'disabled' => TRUE,
     ]);
@@ -78,7 +78,7 @@ public function testOverride() {
   /**
    * Test that each of the major content formats are correctly evaluated.
    */
-  public function testAllTypes() {
+  public function testAllTypes(): void {
     CRM_Core_Region::instance('testAllTypes')->add([
       'markup' => 'some-markup<br/>',
     ]);
@@ -189,7 +189,7 @@ public function testEsm(string $loader) {
   /**
    * Test of nested arrangement in which one {crmRegion} directly includes another {crmRegion}
    */
-  public function testDirectNest() {
+  public function testDirectNest(): void {
     CRM_Core_Region::instance('testDirectNestOuter')->add([
       'template' => 'string:O={$snippet.weight} ',
       'weight' => -5,
@@ -217,7 +217,7 @@ public function testDirectNest() {
   /**
    * Test of nested arrangement in which one {crmRegion} is enhanced with a snippet which, in turn, includes another {crmRegion}
    */
-  public function testIndirectNest() {
+  public function testIndirectNest(): void {
     CRM_Core_Region::instance('testIndirectNestOuter')->add([
       // Note: all three $snippet references are bound to the $snippet which caused this template to be included,
       // regardless of any nested {crmRegion}s
@@ -237,7 +237,7 @@ public function testIndirectNest() {
   /**
    * Output from an inner-region should not be executed verbatim; this is obvious but good to verify
    */
-  public function testNoInjection() {
+  public function testNoInjection(): void {
     CRM_Core_Region::instance('testNoInjectionOuter')->add([
       'template' => 'string:{$snippet.scarystuff} ',
       'scarystuff' => '{$is_outer_scary}',
@@ -260,7 +260,7 @@ public function testNoInjection() {
    * Make sure that standard Smarty variables ($smarty->assign(...)) as well
    * as the magical $snippet variable both evaluate correctly.
    */
-  public function testSmartyVars() {
+  public function testSmartyVars(): void {
     $smarty = CRM_Core_Smarty::singleton();
     $smarty->assign('extrainfo', 'one');
     CRM_Core_Region::instance('testSmartyVars')->add([
@@ -277,7 +277,7 @@ public function testSmartyVars() {
     $this->assertEquals($expected, $actual);
   }
 
-  public function testWeight() {
+  public function testWeight(): void {
     CRM_Core_Region::instance('testWeight')->add([
       'markup' => 'prepend-5<br/>',
       'weight' => -5,
diff --git a/tests/phpunit/CRM/Core/Resources/BundleTest.php b/tests/phpunit/CRM/Core/Resources/BundleTest.php
index b456b8665718..cf056981e818 100644
--- a/tests/phpunit/CRM/Core/Resources/BundleTest.php
+++ b/tests/phpunit/CRM/Core/Resources/BundleTest.php
@@ -28,7 +28,7 @@ public function createEmptyCollection() {
   /**
    * Create two bundles (parent, child) - and merge the child into the parent.
    */
-  public function testMergeIntoRegion() {
+  public function testMergeIntoRegion(): void {
     $bundle = $this->createEmptyCollection();
     $region = CRM_Core_Region::instance(__FUNCTION__);
 
@@ -59,7 +59,7 @@ public function testMergeIntoRegion() {
   /**
    * Add some resources - sometimes forgetting to set a 'region'. Fill in missing regions.
    */
-  public function testFillDefaults() {
+  public function testFillDefaults(): void {
     $bundle = new CRM_Core_Resources_Bundle(__FUNCTION__, ['scriptUrl', 'styleUrl', 'markup']);
     $bundle->addScriptUrl('http://example.com/myscript.js');
     $bundle->addStyleUrl('http://example.com/yonder-style.css', ['region' => 'yonder']);
@@ -75,7 +75,7 @@ public function testFillDefaults() {
   /**
    * Test creation of coreStyles bundle
    */
-  public function testCoreStylesBundle() {
+  public function testCoreStylesBundle(): void {
     $config = CRM_Core_Config::singleton();
     $config->customCSSURL = "http://example.com/css/custom.css";
     $bundle = CRM_Core_Resources_Common::createStyleBundle('coreStyles');
diff --git a/tests/phpunit/CRM/Core/Resources/CollectionTestTrait.php b/tests/phpunit/CRM/Core/Resources/CollectionTestTrait.php
index 05594c7fd81e..f335728dd89a 100644
--- a/tests/phpunit/CRM/Core/Resources/CollectionTestTrait.php
+++ b/tests/phpunit/CRM/Core/Resources/CollectionTestTrait.php
@@ -292,7 +292,7 @@ public function testAddDefaults($callbackArgs, $expectSnippet) {
    * Create a few resources with aliases. Use a mix of reads+writes on both the
    * canonical names and aliased names.
    */
-  public function testAliases() {
+  public function testAliases(): void {
     $b = $this->createEmptyCollection();
     $b->add([
       'styleUrl' => 'https://example.com/foo.css',
@@ -330,7 +330,7 @@ public function testAliases() {
   /**
    * Add some items to a bundle - then clear() all of them.
    */
-  public function testClear() {
+  public function testClear(): void {
     $b = $this->createEmptyCollection();
     $b->addScriptUrl('http://example.com/child.js');
     $this->assertEquals(1, count($b->getAll()));
@@ -347,7 +347,7 @@ public function testClear() {
   /**
    * Create two bundles (parent, child) - and merge the child into the parent.
    */
-  public function testMerge() {
+  public function testMerge(): void {
     $child = $this->createEmptyCollection();
     $parent = $this->createEmptyCollection();
 
@@ -375,7 +375,7 @@ public function testMerge() {
     $this->assertEquals('http://example.com/parent.css', $parent->get('http://example.com/parent.css')['styleUrl']);
   }
 
-  public function testAddBundle() {
+  public function testAddBundle(): void {
     $part1 = $this->createEmptyCollection();
     $part2 = $this->createEmptyCollection();
     $part1->add(['script' => 'doPart1()']);
@@ -393,7 +393,7 @@ public function testAddBundle() {
    * Functions like `addScriptFile()` accept positional arguments
    * in the order ($weight, $region, $translate).
    */
-  public function testStandardSplatParser() {
+  public function testStandardSplatParser(): void {
     $parse = function(...$options) {
       return self::mergeStandardOptions($options, []);
     };
@@ -410,7 +410,7 @@ public function testStandardSplatParser() {
    * Functions like `addVars()` accept positional arguments
    * in the order ($region).
    */
-  public function testSettingsSplatParser() {
+  public function testSettingsSplatParser(): void {
     $parse = function(...$options) {
       return self::mergeSettingOptions($options, []);
     };
diff --git a/tests/phpunit/CRM/Core/Resources/StringsTest.php b/tests/phpunit/CRM/Core/Resources/StringsTest.php
index 6196c688ca86..c18a2d6c4d34 100644
--- a/tests/phpunit/CRM/Core/Resources/StringsTest.php
+++ b/tests/phpunit/CRM/Core/Resources/StringsTest.php
@@ -19,7 +19,7 @@ class CRM_Core_Resources_StringsTest extends CiviUnitTestCase {
   /**
    * Get strings from files.
    */
-  public function testGet() {
+  public function testGet(): void {
     $basedir = $this->createExamples();
     $strings = new CRM_Core_Resources_Strings(
       new CRM_Utils_Cache_ArrayCache(NULL)
diff --git a/tests/phpunit/CRM/Core/ResourcesTest.php b/tests/phpunit/CRM/Core/ResourcesTest.php
index 425f56bf2c31..2c35c8f508bd 100644
--- a/tests/phpunit/CRM/Core/ResourcesTest.php
+++ b/tests/phpunit/CRM/Core/ResourcesTest.php
@@ -63,7 +63,7 @@ public function tearDown(): void {
     parent::tearDown();
   }
 
-  public function testCreateBasicBundle() {
+  public function testCreateBasicBundle(): void {
     $hits = [];
 
     $init = function(CRM_Core_Resources_Bundle $b) use (&$hits) {
@@ -86,7 +86,7 @@ public function testCreateBasicBundle() {
    * Make two bundles (multi-regional). Add them to CRM_Core_Resources.
    * Ensure that the resources land in the right regions.
    */
-  public function testAddBundle() {
+  public function testAddBundle(): void {
     $foo = new CRM_Core_Resources_Bundle('foo', ['scriptUrl', 'styleUrl', 'markup']);
     $bar = new CRM_Core_Resources_Bundle('bar', ['scriptUrl', 'styleUrl', 'markup']);
 
@@ -127,7 +127,7 @@ public function testAddBundle() {
     );
   }
 
-  public function testAddScriptFile() {
+  public function testAddScriptFile(): void {
     $this->res
       ->addScriptFile('com.example.ext', 'foo%20bar.js', 0, 'testAddScriptFile')
       // extra
@@ -148,7 +148,7 @@ public function testAddScriptFile() {
    *
    * FIXME: This can't work because the tests run in English and CRM_Core_Resources optimizes
    * away the English data from $settings['strings']
-   * public function testAddScriptFile_strings() {
+   * public function testAddScriptFile_strings(): void {
    * file_put_contents($this->mapper->keyToBasePath('com.example.ext') . '/hello.js', 'alert(ts("Hello world"));');
    * $this->res->addScriptFile('com.example.ext', 'hello.js', 0, 'testAddScriptFile_strings');
    * $settings = $this->res->getSettings();
@@ -160,7 +160,7 @@ public function testAddScriptFile() {
   /**
    * Ensure that adding a script URL creates expected markup.
    */
-  public function testAddScriptURL() {
+  public function testAddScriptURL(): void {
     $this->res
       ->addScriptUrl('/whiz/foo%20bar.js', 0, 'testAddScriptURL')
       // extra
@@ -176,7 +176,7 @@ public function testAddScriptURL() {
     $this->assertEquals($expected, $actual);
   }
 
-  public function testAddScript() {
+  public function testAddScript(): void {
     $this->res
       ->addScript('alert("hi");', 0, 'testAddScript')
       ->addScript('alert("there");', 0, 'testAddScript');
@@ -189,7 +189,7 @@ public function testAddScript() {
     $this->assertEquals($expected, $actual);
   }
 
-  public function testAddVars() {
+  public function testAddVars(): void {
     $this->res
       ->addVars('food', ['fruit' => ['mine' => 'apple', 'ours' => 'banana']])
       ->addVars('food', ['fruit' => ['mine' => 'new apple', 'yours' => 'orange']]);
@@ -209,7 +209,7 @@ public function testAddVars() {
     );
   }
 
-  public function testAddSetting() {
+  public function testAddSetting(): void {
     $this->res
       ->addSetting(['fruit' => ['mine' => 'apple']])
       ->addSetting(['fruit' => ['yours' => 'orange']]);
@@ -222,7 +222,7 @@ public function testAddSetting() {
     $this->assertTrue(strpos($actual, $expected) !== FALSE);
   }
 
-  public function testAddSettingToBillingBlock() {
+  public function testAddSettingToBillingBlock(): void {
     $this->res
       ->addSetting(['cheese' => ['cheddar' => 'yellow']], 'billing-block')
       ->addSetting(['cheese' => ['edam' => 'red']], 'billing-block');
@@ -235,7 +235,7 @@ public function testAddSettingToBillingBlock() {
     $this->assertTrue(strpos($actual, $expected) !== FALSE);
   }
 
-  public function testAddSettingHook() {
+  public function testAddSettingHook(): void {
     $test = $this;
     Civi::dispatcher()->addListener('hook_civicrm_alterResourceSettings', function($event) use ($test) {
       $test->assertEquals('apple', $event->data['fruit']['mine']);
@@ -246,7 +246,7 @@ public function testAddSettingHook() {
     $this->assertTreeEquals(['fruit' => ['mine' => 'banana']], $settings);
   }
 
-  public function testAddSettingFactory() {
+  public function testAddSettingFactory(): void {
     $this->res->addSettingsFactory(function () {
       return ['fruit' => ['yours' => 'orange']];
     });
@@ -259,7 +259,7 @@ public function testAddSettingFactory() {
     $this->assertTreeEquals($expected, $actual);
   }
 
-  public function testAddSettingAndSettingFactory() {
+  public function testAddSettingAndSettingFactory(): void {
     $this->res->addSetting(['fruit' => ['mine' => 'apple']]);
 
     $muckableValue = ['fruit' => ['yours' => 'orange', 'theirs' => 'apricot']];
@@ -278,7 +278,7 @@ public function testAddSettingAndSettingFactory() {
     $this->assertTreeEquals($expected, $actual);
   }
 
-  public function testCrmJS() {
+  public function testCrmJS(): void {
     $smarty = CRM_Core_Smarty::singleton();
 
     $actual = $smarty->fetch('string:{crmScript ext=com.example.ext file=foo%20bar.js region=testCrmJS}');
@@ -295,7 +295,7 @@ public function testCrmJS() {
     $this->assertEquals($expected, $actual);
   }
 
-  public function testAddStyleFile() {
+  public function testAddStyleFile(): void {
     $this->res
       ->addStyleFile('com.example.ext', 'foo%20bar.css', 0, 'testAddStyleFile')
       // extra
@@ -311,7 +311,7 @@ public function testAddStyleFile() {
     $this->assertEquals($expected, $actual);
   }
 
-  public function testAddStyleURL() {
+  public function testAddStyleURL(): void {
     $this->res
       ->addStyleUrl('/whiz/foo%20bar.css', 0, 'testAddStyleURL')
       // extra
@@ -327,7 +327,7 @@ public function testAddStyleURL() {
     $this->assertEquals($expected, $actual);
   }
 
-  public function testAddStyle() {
+  public function testAddStyle(): void {
     $this->res
       ->addStyle('body { background: black; }', 0, 'testAddStyle')
       ->addStyle('body { text-color: black; }', 0, 'testAddStyle');
@@ -340,7 +340,7 @@ public function testAddStyle() {
     $this->assertEquals($expected, $actual);
   }
 
-  public function testCrmCSS() {
+  public function testCrmCSS(): void {
     $smarty = CRM_Core_Smarty::singleton();
 
     $actual = $smarty->fetch('string:{crmStyle ext=com.example.ext file=foo%20bar.css region=testCrmCSS}');
@@ -357,7 +357,7 @@ public function testCrmCSS() {
     $this->assertEquals($expected, $actual);
   }
 
-  public function testGetURL() {
+  public function testGetURL(): void {
     $this->assertEquals(
       'http://core-app/dir/file%20name.txt',
       $this->res->getURL('civicrm', 'dir/file%20name.txt')
@@ -376,7 +376,7 @@ public function testGetURL() {
     );
   }
 
-  public function testCrmResURL() {
+  public function testCrmResURL(): void {
     $smarty = CRM_Core_Smarty::singleton();
 
     $actual = $smarty->fetch('string:{crmResURL ext=com.example.ext file=foo%20bar.png}');
@@ -392,7 +392,7 @@ public function testCrmResURL() {
     $this->assertEquals(Civi::paths()->getUrl('[civicrm.root]/foo'), $actual);
   }
 
-  public function testGlob() {
+  public function testGlob(): void {
     $this->assertEquals(
       ['info.xml'],
       $this->res->glob('com.example.ext', 'info.xml')
@@ -504,7 +504,7 @@ public function testIsFullyFormedUrl($url, $expected) {
    * Test for hook_civicrm_entityRefFilters().
    *
    */
-  public function testEntityRefFiltersHook() {
+  public function testEntityRefFiltersHook(): void {
     CRM_Utils_Hook_UnitTests::singleton()->setHook('civicrm_entityRefFilters', [$this, 'entityRefFilters']);
     $data = Invasive::call(['CRM_Core_Resources', 'getEntityRefMetadata']);
     $this->assertEquals(count($data['links']['Contact']), 4);
diff --git a/tests/phpunit/CRM/Core/SessionTest.php b/tests/phpunit/CRM/Core/SessionTest.php
index a3264feeede3..1e99a615093a 100644
--- a/tests/phpunit/CRM/Core/SessionTest.php
+++ b/tests/phpunit/CRM/Core/SessionTest.php
@@ -19,7 +19,7 @@ public function setUp(): void {
    * Test that the template setStatus uses gives reasonable output.
    * Test with text only.
    */
-  public function testSetStatusWithTextOnly() {
+  public function testSetStatusWithTextOnly(): void {
     $smarty = CRM_Core_Smarty::singleton();
     $smarty->assign('infoMessage', 'Your refridgerator door is open.');
     $output = $smarty->fetch('CRM/common/info.tpl');
@@ -30,7 +30,7 @@ public function testSetStatusWithTextOnly() {
    * Test that the template setStatus uses gives reasonable output.
    * Test with title only.
    */
-  public function testSetStatusWithTitleOnly() {
+  public function testSetStatusWithTitleOnly(): void {
     $smarty = CRM_Core_Smarty::singleton();
     $smarty->assign('infoTitle', 'Error Error Error.');
     $output = $smarty->fetch('CRM/common/info.tpl');
@@ -41,7 +41,7 @@ public function testSetStatusWithTitleOnly() {
    * Test that the template setStatus uses gives reasonable output.
    * Test with both text and title.
    */
-  public function testSetStatusWithBoth() {
+  public function testSetStatusWithBoth(): void {
     $smarty = CRM_Core_Smarty::singleton();
     $smarty->assign('infoTitle', 'Spoiler alert!');
     $smarty->assign('infoMessage', 'Your refridgerator door is open.');
diff --git a/tests/phpunit/CRM/Core/Smarty/plugins/CrmUpperTest.php b/tests/phpunit/CRM/Core/Smarty/plugins/CrmUpperTest.php
index 4d32e40c9267..c06b139c3721 100644
--- a/tests/phpunit/CRM/Core/Smarty/plugins/CrmUpperTest.php
+++ b/tests/phpunit/CRM/Core/Smarty/plugins/CrmUpperTest.php
@@ -18,7 +18,7 @@ public function setUp(): void {
   /**
    * Test accents with upper
    */
-  public function testUpper() {
+  public function testUpper(): void {
     $smarty = CRM_Core_Smarty::singleton();
     $actual = $smarty->fetch('string:{assign var="nom" value="Pièrre"}{$nom|crmUpper}');
     $this->assertEquals('PIÈRRE', $actual);
diff --git a/tests/phpunit/CRM/Core/SmartyTest.php b/tests/phpunit/CRM/Core/SmartyTest.php
index 9ba928ed93c0..ca1ee8bebcb4 100644
--- a/tests/phpunit/CRM/Core/SmartyTest.php
+++ b/tests/phpunit/CRM/Core/SmartyTest.php
@@ -24,7 +24,7 @@ public function setUp(): void {
    *
    * @see \CRM_Core_Smarty_plugins_CrmScopeTest
    */
-  public function testFetchWith_CleanNonExistent() {
+  public function testFetchWith_CleanNonExistent(): void {
     $smarty = CRM_Core_Smarty::singleton();
     $this->assertFalse(array_key_exists('my_variable', $smarty->get_template_vars()));
 
@@ -44,7 +44,7 @@ public function testFetchWith_CleanNonExistent() {
    *
    * @see \CRM_Core_Smarty_plugins_CrmScopeTest
    */
-  public function testFetchWith_CleanNull() {
+  public function testFetchWith_CleanNull(): void {
     $smarty = CRM_Core_Smarty::singleton();
     $smarty->assign('my_variable', NULL);
     $this->assertEquals(NULL, $smarty->get_template_vars()['my_variable']);
diff --git a/tests/phpunit/CRM/Core/TokenSmartyTest.php b/tests/phpunit/CRM/Core/TokenSmartyTest.php
index 193b4a7c9de1..1c475b6b5711 100644
--- a/tests/phpunit/CRM/Core/TokenSmartyTest.php
+++ b/tests/phpunit/CRM/Core/TokenSmartyTest.php
@@ -25,7 +25,7 @@ public function setUp(): void {
   /**
    * A template which uses both token-data and Smarty-data.
    */
-  public function testMixedData() {
+  public function testMixedData(): void {
     $rendered = CRM_Core_TokenSmarty::render(
       ['msg_subject' => 'First name is {contact.first_name}. ExtraFoo is {$extra.foo}.'],
       ['contactId' => $this->contactId],
@@ -57,7 +57,7 @@ public function testMixedData() {
   /**
    * A template which uses token-data as part of a Smarty expression.
    */
-  public function testTokenInSmarty() {
+  public function testTokenInSmarty(): void {
     \CRM_Utils_Time::setTime('2022-04-08 16:32:04');
     $resetTime = \CRM_Utils_AutoClean::with(['CRM_Utils_Time', 'resetTime']);
 
@@ -132,7 +132,7 @@ public function getDateFormats(): array {
     ];
   }
 
-  public function testTokenDataEscape() {
+  public function testTokenDataEscape(): void {
     $cutesyContactId = $this->individualCreate([
       'first_name' => 'Ivan\'s "The Ter<r>ib`le"',
     ]);
diff --git a/tests/phpunit/CRM/Core/TransactionTest.php b/tests/phpunit/CRM/Core/TransactionTest.php
index f23f0cbe6b07..3d1db106bb81 100644
--- a/tests/phpunit/CRM/Core/TransactionTest.php
+++ b/tests/phpunit/CRM/Core/TransactionTest.php
@@ -188,7 +188,7 @@ public function testMixedBatchRollback_nesting($createStyle, $commitStyle) {
     $this->assertContactsExistByOffset([0 => FALSE, 1 => FALSE, 2 => FALSE]);
   }
 
-  public function testIsActive() {
+  public function testIsActive(): void {
     $this->assertEquals(FALSE, CRM_Core_Transaction::isActive());
     $this->assertEquals(TRUE, CRM_Core_Transaction::willCommit());
     $tx = new CRM_Core_Transaction();
@@ -199,7 +199,7 @@ public function testIsActive() {
     $this->assertEquals(TRUE, CRM_Core_Transaction::willCommit());
   }
 
-  public function testIsActive_rollback() {
+  public function testIsActive_rollback(): void {
     $this->assertEquals(FALSE, CRM_Core_Transaction::isActive());
     $this->assertEquals(TRUE, CRM_Core_Transaction::willCommit());
 
@@ -216,7 +216,7 @@ public function testIsActive_rollback() {
     $this->assertEquals(TRUE, CRM_Core_Transaction::willCommit());
   }
 
-  public function testCallback_commit() {
+  public function testCallback_commit(): void {
     $tx = new CRM_Core_Transaction();
 
     CRM_Core_Transaction::addCallback(CRM_Core_Transaction::PHASE_PRE_COMMIT, [$this, '_preCommit'], [
@@ -244,7 +244,7 @@ public function testCallback_commit() {
     $this->assertEquals(['_postCommit', 'uio', 'p[]'], $this->callbackLog[1]);
   }
 
-  public function testCallback_rollback() {
+  public function testCallback_rollback(): void {
     $tx = new CRM_Core_Transaction();
 
     CRM_Core_Transaction::addCallback(CRM_Core_Transaction::PHASE_PRE_COMMIT, [$this, '_preCommit'], [
diff --git a/tests/phpunit/CRM/Custom/Page/AJAXTest.php b/tests/phpunit/CRM/Custom/Page/AJAXTest.php
index 7735728debb9..018e7a700b11 100644
--- a/tests/phpunit/CRM/Custom/Page/AJAXTest.php
+++ b/tests/phpunit/CRM/Custom/Page/AJAXTest.php
@@ -18,7 +18,7 @@ class CRM_Custom_Page_AJAXTest extends CiviUnitTestCase {
   /**
    * Test multi-record custom fields
    */
-  public function testMultiRecordFieldList() {
+  public function testMultiRecordFieldList(): void {
     //create multi record custom group
     $ids = $this->CustomGroupMultipleCreateWithFields(['style' => 'Tab with table']);
     $params = [
diff --git a/tests/phpunit/CRM/Dedupe/BAO/RuleGroupTest.php b/tests/phpunit/CRM/Dedupe/BAO/RuleGroupTest.php
index f8034db88d29..58832447d574 100644
--- a/tests/phpunit/CRM/Dedupe/BAO/RuleGroupTest.php
+++ b/tests/phpunit/CRM/Dedupe/BAO/RuleGroupTest.php
@@ -205,7 +205,7 @@ public function getSupportedFields() {
    * In general we do have a bit of a problem with having overloaded the meaning of
    * importable & exportable fields.
    */
-  public function testSupportedFields() {
+  public function testSupportedFields(): void {
     $fields = CRM_Dedupe_BAO_DedupeRuleGroup::supportedFields('Organization');
 
     $this->assertEquals($this->getSupportedFields(), $fields);
@@ -215,7 +215,7 @@ public function testSupportedFields() {
    * Test that custom_fields are included in supported fields.
    *
    */
-  public function testSupportedCustomFields() {
+  public function testSupportedCustomFields(): void {
     //Create custom group with fields of all types to test.
     $customGroup = $this->createCustomGroup(['extends' => 'Organization']);
 
@@ -235,7 +235,7 @@ public function testSupportedCustomFields() {
    * dedupe rule.
    *
    */
-  public function testSupportedCustomFieldsSubtype() {
+  public function testSupportedCustomFieldsSubtype(): void {
 
     //Create custom group with fields of all types to test.
     $contactType = $this->callAPISuccess('ContactType', 'create', ['name' => 'Big Bank', 'label' => 'biggee', 'parent_id' => 'Organization']);
diff --git a/tests/phpunit/CRM/Dedupe/MergerTest.php b/tests/phpunit/CRM/Dedupe/MergerTest.php
index 3054a91f7c8a..a5588665be21 100644
--- a/tests/phpunit/CRM/Dedupe/MergerTest.php
+++ b/tests/phpunit/CRM/Dedupe/MergerTest.php
@@ -234,7 +234,7 @@ public function testBatchMergeSelectedDuplicates(): void {
   /**
    * Test the batch merge.
    */
-  public function testBatchMergeAllDuplicates() {
+  public function testBatchMergeAllDuplicates(): void {
     $this->createDupeContacts();
 
     // verify that all contacts have been created separately
@@ -481,7 +481,7 @@ public function testGetMatchesNoCriteriaButLimit(): void {
   /**
    * Test that if criteria are passed and there are no matching contacts no matches are returned.
    */
-  public function testGetMatchesCriteriaNotMatched() {
+  public function testGetMatchesCriteriaNotMatched(): void {
     $this->setupMatchData();
     $pairs = $this->callAPISuccess('Dedupe', 'getduplicates', [
       'rule_group_id' => 1,
@@ -574,7 +574,7 @@ public static function compareDupes($a, $b) {
    *
    * @throws \Exception
    */
-  public function testGetOrganizationMatchesInGroup() {
+  public function testGetOrganizationMatchesInGroup(): void {
     $this->setupMatchData();
     $ruleGroups = $this->callAPISuccessGetSingle('RuleGroup', [
       'contact_type' => 'Organization',
@@ -662,7 +662,7 @@ public function testGetOrganizationMatchesInGroup() {
    * It turns out there are 2 code paths retrieving this data so my initial
    * focus is on ensuring they match.
    */
-  public function testGetMatchesInGroup() {
+  public function testGetMatchesInGroup(): void {
     $this->setupMatchData();
 
     $groupID = $this->groupCreate(['title' => 'she-mice']);
@@ -749,7 +749,7 @@ public function testGetRowsElementsAndInfoSpecialInfo(): void {
   /**
    * Test migration of Membership.
    */
-  public function testMergeMembership() {
+  public function testMergeMembership(): void {
     // Contacts setup
     $this->setupMatchData();
     $originalContactID = $this->contacts[0]['id'];
@@ -884,7 +884,7 @@ public function testCreatedDatePostMerge($keepContactKey, $duplicateContactKey)
    * of the custom fields of that custom table are selected, the value is not
    * merged in.
    */
-  public function testMigrationOfUnselectedCustomDataOnEmptyCustomRecord() {
+  public function testMigrationOfUnselectedCustomDataOnEmptyCustomRecord(): void {
     // Create Custom Fields
     $createGroup = $this->setupCustomGroupForIndividual();
     $customField1 = $this->setupCustomField('TestField', $createGroup);
@@ -934,7 +934,7 @@ public function testMigrationOfUnselectedCustomDataOnEmptyCustomRecord() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testMigrationOfSomeCustomDataOnEmptyCustomRecord() {
+  public function testMigrationOfSomeCustomDataOnEmptyCustomRecord(): void {
     // Create Custom Fields
     $createGroup = $this->setupCustomGroupForIndividual();
     $customField1 = $this->setupCustomField('Test1', $createGroup);
@@ -989,7 +989,7 @@ public function testMigrationOfSomeCustomDataOnEmptyCustomRecord() {
    * @throws \CRM_Core_Exception
    * @throws \Civi\API\Exception\UnauthorizedException
    */
-  public function testMigrationOfContactReferenceCustomField() {
+  public function testMigrationOfContactReferenceCustomField(): void {
     // Create Custom Fields
     $contactGroup = $this->setupCustomGroupForIndividual();
     $activityGroup = $this->customGroupCreate([
@@ -1050,7 +1050,7 @@ public function testMigrationOfContactReferenceCustomField() {
    * Verifies that when two contacts with view only custom fields are merged,
    * the view only field of the record being deleted is merged.
    */
-  public function testMigrationOfViewOnlyCustomData() {
+  public function testMigrationOfViewOnlyCustomData(): void {
     // Create Custom Fields
     $createGroup = $this->setupCustomGroupForIndividual();
     $customField = $this->setupCustomField('TestField', $createGroup);
diff --git a/tests/phpunit/CRM/Event/BAO/ParticipantStatusTest.php b/tests/phpunit/CRM/Event/BAO/ParticipantStatusTest.php
index 7ed735291c84..190232af4328 100644
--- a/tests/phpunit/CRM/Event/BAO/ParticipantStatusTest.php
+++ b/tests/phpunit/CRM/Event/BAO/ParticipantStatusTest.php
@@ -20,7 +20,7 @@ class CRM_Event_BAO_ParticipantStatusTest extends CiviUnitTestCase {
   /**
    *  create() and deleteParticipantStatusType() method
    */
-  public function testCreateAndDelete() {
+  public function testCreateAndDelete(): void {
 
     // create using required params
     $params = [
@@ -47,7 +47,7 @@ public function testCreateAndDelete() {
   /**
    *  add() method (add and edit modes of participant status type)
    */
-  public function testAddStatusType() {
+  public function testAddStatusType(): void {
 
     $params = [
       'name' => 'testStatus',
@@ -86,7 +86,7 @@ public function testAddStatusType() {
   /**
    * Retrieve() method of participant status type
    */
-  public function testRetrieveStatusType() {
+  public function testRetrieveStatusType(): void {
 
     $params = [
       'name' => 'testStatus',
diff --git a/tests/phpunit/CRM/Event/BAO/QueryTest.php b/tests/phpunit/CRM/Event/BAO/QueryTest.php
index 89ae38ba9cec..6548c0897d0c 100644
--- a/tests/phpunit/CRM/Event/BAO/QueryTest.php
+++ b/tests/phpunit/CRM/Event/BAO/QueryTest.php
@@ -14,7 +14,7 @@ public function setUp(): void {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testParticipantNote() {
+  public function testParticipantNote(): void {
     $event = $this->eventCreateUnpaid();
     $this->individualCreate([
       'api.participant.create' => [
@@ -49,7 +49,7 @@ public function testParticipantNote() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testEventType() {
+  public function testEventType(): void {
     $event = $this->eventCreateUnpaid();
     $contactId = $this->individualCreate([
       'api.participant.create' => [
diff --git a/tests/phpunit/CRM/Event/Form/ManageEvent/EventInfoTest.php b/tests/phpunit/CRM/Event/Form/ManageEvent/EventInfoTest.php
index 6a9d7ce8ec95..180180e7e991 100644
--- a/tests/phpunit/CRM/Event/Form/ManageEvent/EventInfoTest.php
+++ b/tests/phpunit/CRM/Event/Form/ManageEvent/EventInfoTest.php
@@ -20,7 +20,7 @@ private function getCorrectFormFields() {
   /**
    * Test correct form submission.
    */
-  public function testValidFormSubmission() {
+  public function testValidFormSubmission(): void {
     $values = $this->getCorrectFormFields();
     $validationResult = \CRM_Event_Form_ManageEvent_EventInfo::formRule($values);
     $this->assertEmpty($validationResult);
@@ -29,7 +29,7 @@ public function testValidFormSubmission() {
   /**
    * Test end date not allowed with only 'time' part.
    */
-  public function testEndDateWithoutDateNotAllowed() {
+  public function testEndDateWithoutDateNotAllowed(): void {
     $values = $this->getCorrectFormFields();
     $values['end_date'] = '00:01';
     $validationResult = \CRM_Event_Form_ManageEvent_EventInfo::formRule($values);
@@ -39,7 +39,7 @@ public function testEndDateWithoutDateNotAllowed() {
   /**
    * Test end date must be after start date.
    */
-  public function testEndDateBeforeStartDateNotAllowed() {
+  public function testEndDateBeforeStartDateNotAllowed(): void {
     $values = $this->getCorrectFormFields();
     $values['end_date'] = '1900-01-01 00:00';
     $validationResult = \CRM_Event_Form_ManageEvent_EventInfo::formRule($values);
diff --git a/tests/phpunit/CRM/Event/Form/ManageEvent/RegistrationTest.php b/tests/phpunit/CRM/Event/Form/ManageEvent/RegistrationTest.php
index c1aea66c2203..f32e3fb1aef2 100644
--- a/tests/phpunit/CRM/Event/Form/ManageEvent/RegistrationTest.php
+++ b/tests/phpunit/CRM/Event/Form/ManageEvent/RegistrationTest.php
@@ -23,7 +23,7 @@ private function getCorrectFormFields() {
   /**
    * Test end date not allowed with only 'time' part.
    */
-  public function testEndDateWithoutDateNotAllowed() {
+  public function testEndDateWithoutDateNotAllowed(): void {
     $values = $this->getCorrectFormFields();
     $values['registration_end_date'] = '00:01';
     $form = new CRM_Event_Form_ManageEvent_Registration();
@@ -34,7 +34,7 @@ public function testEndDateWithoutDateNotAllowed() {
   /**
    * Test end date must be after start date.
    */
-  public function testEndDateBeforeStartDateNotAllowed() {
+  public function testEndDateBeforeStartDateNotAllowed(): void {
     $values = $this->getCorrectFormFields();
     $values['registration_end_date'] = '1900-01-01 00:00';
     $form = new CRM_Event_Form_ManageEvent_Registration();
diff --git a/tests/phpunit/CRM/Event/Form/SearchTest.php b/tests/phpunit/CRM/Event/Form/SearchTest.php
index 6d7da4f262bd..9ad8a7d27d2f 100644
--- a/tests/phpunit/CRM/Event/Form/SearchTest.php
+++ b/tests/phpunit/CRM/Event/Form/SearchTest.php
@@ -64,7 +64,7 @@ public function testSearch(): void {
     $this->assertEquals(1, count($rows), 'Exactly one row should be returned for given price field value.');
   }
 
-  public function testSearchWithPricelabelChange() {
+  public function testSearchWithPricelabelChange(): void {
     $this->callAPISuccess('PriceFieldValue', 'create', [
       'label' => 'Radio Label C',
       'id' => $this->participantPrice['id'],
diff --git a/tests/phpunit/CRM/Event/Form/Task/BatchTest.php b/tests/phpunit/CRM/Event/Form/Task/BatchTest.php
index f375583bf958..7f3fd348ae8c 100644
--- a/tests/phpunit/CRM/Event/Form/Task/BatchTest.php
+++ b/tests/phpunit/CRM/Event/Form/Task/BatchTest.php
@@ -12,7 +12,7 @@ class CRM_Event_Form_Task_BatchTest extends CiviUnitTestCase {
   /**
    * Test the the submit function on the event participant submit function.
    */
-  public function testSubmit() {
+  public function testSubmit(): void {
     $group = $this->customGroupCreate(['extends' => 'Participant', 'title' => 'Participant']);
     $field = $this->customFieldCreate(['custom_group_id' => $group['id'], 'html_type' => 'CheckBox', 'option_values' => ['two' => 'A couple', 'three' => 'A few', 'four' => 'Too Many']]);
     $participantID = $this->participantCreate();
diff --git a/tests/phpunit/CRM/Event/Form/Task/RegisterTest.php b/tests/phpunit/CRM/Event/Form/Task/RegisterTest.php
index c4aa82df2641..acbc8679fbd3 100644
--- a/tests/phpunit/CRM/Event/Form/Task/RegisterTest.php
+++ b/tests/phpunit/CRM/Event/Form/Task/RegisterTest.php
@@ -13,7 +13,7 @@ class CRM_Event_Form_Task_RegisterTest extends CiviUnitTestCase {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testGet() {
+  public function testGet(): void {
     /** @var CRM_Event_Form_Task_Register $form */
     $form = $this->getFormObject('CRM_Event_Form_Task_Register');
     $this->assertEquals(FALSE, $form->_single);
diff --git a/tests/phpunit/CRM/Extension/BrowserTest.php b/tests/phpunit/CRM/Extension/BrowserTest.php
index 05199961960a..61cc0e803bd4 100644
--- a/tests/phpunit/CRM/Extension/BrowserTest.php
+++ b/tests/phpunit/CRM/Extension/BrowserTest.php
@@ -35,14 +35,14 @@ protected function setupMockHandler() {
     $this->browser->setGuzzleClient($this->getGuzzleClient());
   }
 
-  public function testDisabled() {
+  public function testDisabled(): void {
     $this->browser = new CRM_Extension_Browser(FALSE, '/index.html');
     $this->assertEquals(FALSE, $this->browser->isEnabled());
     $this->assertEquals([], $this->browser->checkRequirements());
     $this->assertEquals([], $this->browser->getExtensions());
   }
 
-  public function testGetExtensions_good() {
+  public function testGetExtensions_good(): void {
     $this->browser = new CRM_Extension_Browser('file://' . dirname(__FILE__) . '/dataset/good-repository', NULL);
     $this->assertEquals(TRUE, $this->browser->isEnabled());
     $this->assertEquals([], $this->browser->checkRequirements());
@@ -57,7 +57,7 @@ public function testGetExtensions_good() {
     $this->assertEquals('http://example.com/test.crm.extension.browsertest.b-1.2.zip', $exts['test.crm.extension.browsertest.b']->downloadUrl);
   }
 
-  public function testGetExtension_good() {
+  public function testGetExtension_good(): void {
     $this->browser = new CRM_Extension_Browser('file://' . dirname(__FILE__) . '/dataset/good-repository', NULL);
     $this->assertEquals(TRUE, $this->browser->isEnabled());
     $this->assertEquals([], $this->browser->checkRequirements());
@@ -67,7 +67,7 @@ public function testGetExtension_good() {
     $this->assertEquals('http://example.com/test.crm.extension.browsertest.b-1.2.zip', $info->downloadUrl);
   }
 
-  public function testGetExtension_nonexistent() {
+  public function testGetExtension_nonexistent(): void {
     $this->browser = new CRM_Extension_Browser('file://' . dirname(__FILE__) . '/dataset/good-repository', NULL);
     $this->assertEquals(TRUE, $this->browser->isEnabled());
     $this->assertEquals([], $this->browser->checkRequirements());
diff --git a/tests/phpunit/CRM/Extension/Container/BasicTest.php b/tests/phpunit/CRM/Extension/Container/BasicTest.php
index a36edc3886fa..88bf5156431c 100644
--- a/tests/phpunit/CRM/Extension/Container/BasicTest.php
+++ b/tests/phpunit/CRM/Extension/Container/BasicTest.php
@@ -6,18 +6,18 @@
  */
 class CRM_Extension_Container_BasicTest extends CiviUnitTestCase {
 
-  public function testGetKeysEmpty() {
+  public function testGetKeysEmpty(): void {
     $basedir = $this->createTempDir('ext-empty-');
     $c = new CRM_Extension_Container_Basic($basedir, 'http://example/basedir', NULL, NULL);
     $this->assertEquals($c->getKeys(), []);
   }
 
-  public function testGetKeys() {
+  public function testGetKeys(): void {
     [$basedir, $c] = $this->_createContainer();
     $this->assertEquals($c->getKeys(), ['test.foo', 'test.foo.bar']);
   }
 
-  public function testGetPath() {
+  public function testGetPath(): void {
     [$basedir, $c] = $this->_createContainer();
     try {
       $c->getPath('un.kno.wn');
@@ -31,7 +31,7 @@ public function testGetPath() {
     $this->assertEquals("$basedir/foo/bar", $c->getPath('test.foo.bar'));
   }
 
-  public function testGetPath_extraSlashFromConfig() {
+  public function testGetPath_extraSlashFromConfig(): void {
     [$basedir, $c] = $this->_createContainer(NULL, NULL, '/');
     try {
       $c->getPath('un.kno.wn');
@@ -45,7 +45,7 @@ public function testGetPath_extraSlashFromConfig() {
     $this->assertEquals("$basedir/foo/bar", $c->getPath('test.foo.bar'));
   }
 
-  public function testGetResUrl() {
+  public function testGetResUrl(): void {
     [$basedir, $c] = $this->_createContainer();
     try {
       $c->getResUrl('un.kno.wn');
@@ -59,7 +59,7 @@ public function testGetResUrl() {
     $this->assertEquals('http://example/basedir/foo/bar', $c->getResUrl('test.foo.bar'));
   }
 
-  public function testGetResUrl_extraSlashFromConfig() {
+  public function testGetResUrl_extraSlashFromConfig(): void {
     [$basedir, $c] = $this->_createContainer(NULL, NULL, '/');
     try {
       $c->getResUrl('un.kno.wn');
@@ -73,7 +73,7 @@ public function testGetResUrl_extraSlashFromConfig() {
     $this->assertEquals('http://example/basedir/foo/bar', $c->getResUrl('test.foo.bar'));
   }
 
-  public function testCaching() {
+  public function testCaching(): void {
     $cache = new CRM_Utils_Cache_ArrayCache([]);
     $this->assertTrue(!is_array($cache->get('basic-scan')));
     [$basedir, $c] = $this->_createContainer($cache, 'basic-scan');
@@ -103,7 +103,7 @@ public function _createContainer(CRM_Utils_Cache_Interface $cache = NULL, $cache
     return [$basedir, $c];
   }
 
-  public function testConvertPathsToUrls() {
+  public function testConvertPathsToUrls(): void {
     $relPaths = [
       'foo.bar' => 'foo\bar',
       'whiz.bang' => 'tests\extensions\whiz\bang',
diff --git a/tests/phpunit/CRM/Extension/Container/CollectionTest.php b/tests/phpunit/CRM/Extension/Container/CollectionTest.php
index 9ecba0b5a49e..f12733ff29f3 100644
--- a/tests/phpunit/CRM/Extension/Container/CollectionTest.php
+++ b/tests/phpunit/CRM/Extension/Container/CollectionTest.php
@@ -15,12 +15,12 @@
  */
 class CRM_Extension_Container_CollectionTest extends CiviUnitTestCase {
 
-  public function testGetKeysEmpty() {
+  public function testGetKeysEmpty(): void {
     $c = new CRM_Extension_Container_Collection([]);
     $this->assertEquals($c->getKeys(), []);
   }
 
-  public function testGetKeys() {
+  public function testGetKeys(): void {
     $c = $this->_createContainer();
     $this->assertEquals([
       'test.conflict',
@@ -31,7 +31,7 @@ public function testGetKeys() {
     ], $c->getKeys());
   }
 
-  public function testGetPath() {
+  public function testGetPath(): void {
     $c = $this->_createContainer();
     try {
       $c->getPath('un.kno.wn');
@@ -48,7 +48,7 @@ public function testGetPath() {
     $this->assertEquals("/path/to/conflict-b", $c->getPath('test.conflict'));
   }
 
-  public function testGetResUrl() {
+  public function testGetResUrl(): void {
     $c = $this->_createContainer();
     try {
       $c->getResUrl('un.kno.wn');
@@ -65,7 +65,7 @@ public function testGetResUrl() {
     $this->assertEquals('http://conflict-b', $c->getResUrl('test.conflict'));
   }
 
-  public function testCaching() {
+  public function testCaching(): void {
     $cache = new CRM_Utils_Cache_ArrayCache([]);
     $this->assertTrue(!is_array($cache->get('ext-collection')));
     $c = $this->_createContainer($cache, 'ext-collection');
diff --git a/tests/phpunit/CRM/Extension/Container/StaticTest.php b/tests/phpunit/CRM/Extension/Container/StaticTest.php
index d15e0b6f1554..fbc7f107649e 100644
--- a/tests/phpunit/CRM/Extension/Container/StaticTest.php
+++ b/tests/phpunit/CRM/Extension/Container/StaticTest.php
@@ -6,17 +6,17 @@
  */
 class CRM_Extension_Container_StaticTest extends CiviUnitTestCase {
 
-  public function testGetKeysEmpty() {
+  public function testGetKeysEmpty(): void {
     $c = new CRM_Extension_Container_Static([]);
     $this->assertEquals($c->getKeys(), []);
   }
 
-  public function testGetKeys() {
+  public function testGetKeys(): void {
     $c = $this->_createContainer();
     $this->assertEquals($c->getKeys(), ['test.foo', 'test.foo.bar']);
   }
 
-  public function testGetPath() {
+  public function testGetPath(): void {
     $c = $this->_createContainer();
     try {
       $c->getPath('un.kno.wn');
@@ -30,7 +30,7 @@ public function testGetPath() {
     $this->assertEquals("/path/to/bar", $c->getPath('test.foo.bar'));
   }
 
-  public function testGetResUrl() {
+  public function testGetResUrl(): void {
     $c = $this->_createContainer();
     try {
       $c->getResUrl('un.kno.wn');
diff --git a/tests/phpunit/CRM/Extension/InfoTest.php b/tests/phpunit/CRM/Extension/InfoTest.php
index 2d3452ce1da1..d684b9cb8c6b 100644
--- a/tests/phpunit/CRM/Extension/InfoTest.php
+++ b/tests/phpunit/CRM/Extension/InfoTest.php
@@ -23,7 +23,7 @@ public function tearDown(): void {
     parent::tearDown();
   }
 
-  public function testGood_file() {
+  public function testGood_file(): void {
     $this->file = tempnam(sys_get_temp_dir(), 'infoxml-');
     file_put_contents($this->file, "<extension key='test.foo' type='module'><file>foo</file><typeInfo><extra>zamboni</extra></typeInfo></extension>");
 
@@ -33,7 +33,7 @@ public function testGood_file() {
     $this->assertEquals('zamboni', $info->typeInfo['extra']);
   }
 
-  public function testBad_file() {
+  public function testBad_file(): void {
     // <file> vs file>
     $this->file = tempnam(sys_get_temp_dir(), 'infoxml-');
     file_put_contents($this->file, "<extension key='test.foo' type='module'>file>foo</file></extension>");
@@ -48,7 +48,7 @@ public function testBad_file() {
     $this->assertTrue(is_object($exc));
   }
 
-  public function testGood_string() {
+  public function testGood_string(): void {
     $data = "<extension key='test.foo' type='module'><file>foo</file><typeInfo><extra>zamboni</extra></typeInfo></extension>";
 
     $info = CRM_Extension_Info::loadFromString($data);
@@ -59,7 +59,7 @@ public function testGood_string() {
     $this->assertEquals([], $info->requires);
   }
 
-  public function testGood_string_extras() {
+  public function testGood_string_extras(): void {
     $data = "<extension key='test.bar' type='module'><file>testbar</file>
       <classloader>
         <psr4 prefix=\"Civi\\\" path=\"Civi\"/>
@@ -115,7 +115,7 @@ public function testAuthors($xmlString, $expectAuthors, $expectMaintainer) {
     $this->assertEquals($expectMaintainer, $info->maintainer);
   }
 
-  public function testBad_string() {
+  public function testBad_string(): void {
     // <file> vs file>
     $data = "<extension key='test.foo' type='module'>file>foo</file></extension>";
 
@@ -129,7 +129,7 @@ public function testBad_string() {
     $this->assertTrue(is_object($exc));
   }
 
-  public function test_requirements() {
+  public function test_requirements(): void {
     // Quicksearch requirement should get filtered out per extension-compatibility.json
     $data = "<extension key='test.foo' type='module'><file>foo</file><requires><ext>example.test</ext><ext>com.ixiam.modules.quicksearch</ext></requires></extension>";
 
diff --git a/tests/phpunit/CRM/Extension/Manager/ModuleTest.php b/tests/phpunit/CRM/Extension/Manager/ModuleTest.php
index 3599dbe35018..682db28bb422 100644
--- a/tests/phpunit/CRM/Extension/Manager/ModuleTest.php
+++ b/tests/phpunit/CRM/Extension/Manager/ModuleTest.php
@@ -38,7 +38,7 @@ public function tearDown(): void {
   /**
    * Install an extension with a valid type name.
    */
-  public function testInstallDisableUninstall() {
+  public function testInstallDisableUninstall(): void {
     $manager = $this->system->getManager();
     $this->assertModuleActiveByName(FALSE, 'moduletest');
 
@@ -79,7 +79,7 @@ public function testInstallDisableUninstall() {
   /**
    * Install an extension with a valid type name.
    */
-  public function testInstallDisableEnable() {
+  public function testInstallDisableEnable(): void {
     $manager = $this->system->getManager();
     $this->assertModuleActiveByName(FALSE, 'moduletest');
     $this->assertModuleActiveByKey(FALSE, 'test.extension.manager.moduletest');
@@ -118,7 +118,7 @@ public function testInstallDisableEnable() {
   /**
    * Install an extension then forcibly remove the code and cleanup DB afterwards.
    */
-  public function testInstall_DirtyRemove_Disable_Uninstall() {
+  public function testInstall_DirtyRemove_Disable_Uninstall(): void {
     // create temporary extension (which can dirtily remove later)
     $this->_createExtension('test.extension.manager.module.auto1', 'module', 'test_extension_manager_module_auto1');
     $mainfile = $this->basedir . '/test.extension.manager.module.auto1/test_extension_manager_module_auto1.php';
@@ -174,7 +174,7 @@ public function testInstall_DirtyRemove_Disable_Uninstall() {
   /**
    * Install an extension then forcibly remove the code and cleanup DB afterwards.
    */
-  public function testInstall_DirtyRemove_Disable_Restore() {
+  public function testInstall_DirtyRemove_Disable_Restore(): void {
     // create temporary extension (which can dirtily remove later)
     $this->_createExtension('test.extension.manager.module.auto2', 'module', 'test_extension_manager_module_auto2');
     $mainfile = $this->basedir . '/test.extension.manager.module.auto2/test_extension_manager_module_auto2.php';
diff --git a/tests/phpunit/CRM/Extension/Manager/ModuleUpgTest.php b/tests/phpunit/CRM/Extension/Manager/ModuleUpgTest.php
index b2c67d66fbbd..4c4dc34504b3 100644
--- a/tests/phpunit/CRM/Extension/Manager/ModuleUpgTest.php
+++ b/tests/phpunit/CRM/Extension/Manager/ModuleUpgTest.php
@@ -38,7 +38,7 @@ public function tearDown(): void {
   /**
    * Install an extension with a valid type name.
    */
-  public function testInstallDisableUninstall() {
+  public function testInstallDisableUninstall(): void {
     $manager = $this->system->getManager();
     $this->assertModuleActiveByName(FALSE, 'moduleupgtest');
 
@@ -79,7 +79,7 @@ public function testInstallDisableUninstall() {
   /**
    * Install an extension with a valid type name.
    */
-  public function testInstallDisableEnable() {
+  public function testInstallDisableEnable(): void {
     $manager = $this->system->getManager();
     $this->assertModuleActiveByName(FALSE, 'moduleupgtest');
     $this->assertModuleActiveByKey(FALSE, 'test.extension.manager.moduleupgtest');
@@ -118,7 +118,7 @@ public function testInstallDisableEnable() {
   /**
    * Install an extension then forcibly remove the code and cleanup DB afterwards.
    */
-  public function testInstall_DirtyRemove_Disable_Uninstall() {
+  public function testInstall_DirtyRemove_Disable_Uninstall(): void {
     // create temporary extension (which can dirtily remove later)
     $this->_createExtension('test.extension.manager.moduleupg.auto1', 'module', 'test_extension_manager_moduleupg_auto1');
     $mainfile = $this->basedir . '/test.extension.manager.moduleupg.auto1/test_extension_manager_moduleupg_auto1.php';
@@ -174,7 +174,7 @@ public function testInstall_DirtyRemove_Disable_Uninstall() {
   /**
    * Install an extension then forcibly remove the code and cleanup DB afterwards.
    */
-  public function testInstall_DirtyRemove_Disable_Restore() {
+  public function testInstall_DirtyRemove_Disable_Restore(): void {
     // create temporary extension (which can dirtily remove later)
     $this->_createExtension('test.extension.manager.moduleupg.auto2', 'module', 'test_extension_manager_moduleupg_auto2');
     $mainfile = $this->basedir . '/test.extension.manager.moduleupg.auto2/test_extension_manager_moduleupg_auto2.php';
diff --git a/tests/phpunit/CRM/Extension/Manager/PaymentTest.php b/tests/phpunit/CRM/Extension/Manager/PaymentTest.php
index c33d56926953..f791d70c2898 100644
--- a/tests/phpunit/CRM/Extension/Manager/PaymentTest.php
+++ b/tests/phpunit/CRM/Extension/Manager/PaymentTest.php
@@ -42,7 +42,7 @@ public function tearDown(): void {
   /**
    * Install an extension with a valid type name.
    */
-  public function testInstallDisableUninstall() {
+  public function testInstallDisableUninstall(): void {
     $manager = $this->system->getManager();
     $this->assertDBQuery(0, 'SELECT count(*) FROM civicrm_payment_processor_type WHERE class_name = "test.extension.manager.paymenttest"');
     $manager->install(['test.extension.manager.paymenttest']);
@@ -62,7 +62,7 @@ public function testInstallDisableUninstall() {
   /**
    * Install an extension with a valid type name.
    */
-  public function testInstallDisableEnable() {
+  public function testInstallDisableEnable(): void {
     $manager = $this->system->getManager();
     $this->assertDBQuery(0, 'SELECT count(*) FROM civicrm_payment_processor_type WHERE class_name = "test.extension.manager.paymenttest"');
 
@@ -85,7 +85,7 @@ public function testInstallDisableEnable() {
    * Install an extension and create a payment processor which uses it.
    * Attempts to uninstall fail
    */
-  public function testInstall_Add_FailUninstall() {
+  public function testInstall_Add_FailUninstall(): void {
     $manager = $this->system->getManager();
     $this->assertDBQuery(0, 'SELECT count(*) FROM civicrm_payment_processor_type WHERE class_name = "test.extension.manager.paymenttest"');
 
diff --git a/tests/phpunit/CRM/Extension/Manager/ReportTest.php b/tests/phpunit/CRM/Extension/Manager/ReportTest.php
index 0bd742cd1115..10580e8c0a05 100644
--- a/tests/phpunit/CRM/Extension/Manager/ReportTest.php
+++ b/tests/phpunit/CRM/Extension/Manager/ReportTest.php
@@ -25,7 +25,7 @@ public function setUp(): void {
   /**
    * Install an extension with a valid type name.
    */
-  public function testInstallDisableUninstall() {
+  public function testInstallDisableUninstall(): void {
     $manager = $this->system->getManager();
     $this->assertDBQuery(0, 'SELECT count(*) FROM civicrm_option_value WHERE name = "test.extension.manager.reporttest"');
 
@@ -43,7 +43,7 @@ public function testInstallDisableUninstall() {
   /**
    * Install an extension with a valid type name.
    */
-  public function testInstallDisableEnable() {
+  public function testInstallDisableEnable(): void {
     $manager = $this->system->getManager();
     $this->assertDBQuery(0, 'SELECT count(*) FROM civicrm_option_value WHERE name = "test.extension.manager.reporttest"');
 
diff --git a/tests/phpunit/CRM/Extension/Manager/SearchTest.php b/tests/phpunit/CRM/Extension/Manager/SearchTest.php
index 6053d64e3d3a..51892c688fbf 100644
--- a/tests/phpunit/CRM/Extension/Manager/SearchTest.php
+++ b/tests/phpunit/CRM/Extension/Manager/SearchTest.php
@@ -30,7 +30,7 @@ public function tearDown(): void {
   /**
    * Install an extension with a valid type name.
    */
-  public function testInstallDisableUninstall() {
+  public function testInstallDisableUninstall(): void {
     $manager = $this->system->getManager();
     $this->assertDBQuery(0, 'SELECT count(*) FROM civicrm_option_value WHERE name = "test.extension.manager.searchtest"');
 
@@ -48,7 +48,7 @@ public function testInstallDisableUninstall() {
   /**
    * Install an extension with a valid type name.
    */
-  public function testInstallDisableEnable() {
+  public function testInstallDisableEnable(): void {
     $manager = $this->system->getManager();
     $this->assertDBQuery(0, 'SELECT count(*) FROM civicrm_option_value WHERE name = "test.extension.manager.searchtest"');
 
diff --git a/tests/phpunit/CRM/Extension/ManagerTest.php b/tests/phpunit/CRM/Extension/ManagerTest.php
index 362d9413a335..3ecb0c235a01 100644
--- a/tests/phpunit/CRM/Extension/ManagerTest.php
+++ b/tests/phpunit/CRM/Extension/ManagerTest.php
@@ -41,7 +41,7 @@ public function setUp(): void {
   /**
    * Install an extension with an invalid type name.
    */
-  public function testInstallInvalidType() {
+  public function testInstallInvalidType(): void {
     $this->expectException(CRM_Extension_Exception::class);
     $testingTypeManager = $this->getMockBuilder('CRM_Extension_Manager_Interface')->getMock();
     $testingTypeManager->expects($this->never())
@@ -59,7 +59,7 @@ public function testInstallInvalidType() {
    * the second. This controls for bad SQL queries which hit either
    * "the first row" or "all rows".
    */
-  public function testInstall_Disable_Uninstall() {
+  public function testInstall_Disable_Uninstall(): void {
     $testingTypeManager = $this->getMockBuilder('CRM_Extension_Manager_Interface')->getMock();
     $manager = $this->_createManager([
       self::TESTING_TYPE => $testingTypeManager,
@@ -105,7 +105,7 @@ public function testInstall_Disable_Uninstall() {
    *
    * @throws \CRM_Extension_Exception
    */
-  public function test_InstallAuto_DisableDownstream_UninstallDownstream() {
+  public function test_InstallAuto_DisableDownstream_UninstallDownstream(): void {
     $testingTypeManager = $this->getMockBuilder('CRM_Extension_Manager_Interface')->getMock();
     $manager = $this->_createManager([
       self::TESTING_TYPE => $testingTypeManager,
@@ -146,7 +146,7 @@ public function test_InstallAuto_DisableDownstream_UninstallDownstream() {
    *
    * @throws \CRM_Extension_Exception
    */
-  public function testInstallAuto_Twice() {
+  public function testInstallAuto_Twice(): void {
     $testingTypeManager = $this->getMockBuilder('CRM_Extension_Manager_Interface')->getMock();
     $manager = $this->_createManager([
       self::TESTING_TYPE => $testingTypeManager,
@@ -175,7 +175,7 @@ public function testInstallAuto_Twice() {
     $this->assertEquals('uninstalled', $manager->getStatus('test.whiz.bang'));
   }
 
-  public function test_InstallAuto_DisableUpstream() {
+  public function test_InstallAuto_DisableUpstream(): void {
     $testingTypeManager = $this->getMockBuilder('CRM_Extension_Manager_Interface')->getMock();
     $manager = $this->_createManager([
       self::TESTING_TYPE => $testingTypeManager,
@@ -217,7 +217,7 @@ public function test_InstallAuto_DisableUpstream() {
    * Install an extension and then harshly remove the underlying source.
    * Subseuently disable and uninstall.
    */
-  public function testInstall_DirtyRemove_Disable_Uninstall() {
+  public function testInstall_DirtyRemove_Disable_Uninstall(): void {
     $testingTypeManager = $this->getMockBuilder('CRM_Extension_Manager_Interface')->getMock();
     $manager = $this->_createManager([
       self::TESTING_TYPE => $testingTypeManager,
@@ -255,7 +255,7 @@ public function testInstall_DirtyRemove_Disable_Uninstall() {
   /**
    * Install an extension with a valid type name.
    */
-  public function testInstall_Disable_Enable() {
+  public function testInstall_Disable_Enable(): void {
     $testingTypeManager = $this->getMockBuilder('CRM_Extension_Manager_Interface')->getMock();
     $manager = $this->_createManager([
       self::TESTING_TYPE => $testingTypeManager,
@@ -297,7 +297,7 @@ public function testInstall_Disable_Enable() {
   /**
    * Performing 'install' on a 'disabled' extension performs an 'enable'
    */
-  public function testInstall_Disable_Install() {
+  public function testInstall_Disable_Install(): void {
     $testingTypeManager = $this->getMockBuilder('CRM_Extension_Manager_Interface')->getMock();
     $manager = $this->_createManager([
       self::TESTING_TYPE => $testingTypeManager,
@@ -336,7 +336,7 @@ public function testInstall_Disable_Install() {
   /**
    * Install an extension with a valid type name.
    */
-  public function testEnableBare() {
+  public function testEnableBare(): void {
     $testingTypeManager = $this->getMockBuilder('CRM_Extension_Manager_Interface')->getMock();
     $manager = $this->_createManager([
       self::TESTING_TYPE => $testingTypeManager,
@@ -363,7 +363,7 @@ public function testEnableBare() {
   /**
    * Get the status of an unknown extension.
    */
-  public function testStatusUnknownKey() {
+  public function testStatusUnknownKey(): void {
     $testingTypeManager = $this->getMockBuilder('CRM_Extension_Manager_Interface')->getMock();
     $testingTypeManager->expects($this->never())
       ->method('onPreInstall');
@@ -376,7 +376,7 @@ public function testStatusUnknownKey() {
   /**
    * Replace code for an extension that doesn't exist in the container
    */
-  public function testReplace_Unknown() {
+  public function testReplace_Unknown(): void {
     $testingTypeManager = $this->getMockBuilder('CRM_Extension_Manager_Interface')->getMock();
     $manager = $this->_createManager([
       self::TESTING_TYPE => $testingTypeManager,
@@ -404,7 +404,7 @@ public function testReplace_Unknown() {
   /**
    * Replace code for an extension that doesn't exist in the container
    */
-  public function testReplace_Uninstalled() {
+  public function testReplace_Uninstalled(): void {
     $testingTypeManager = $this->getMockBuilder('CRM_Extension_Manager_Interface')->getMock();
     $manager = $this->_createManager([
       self::TESTING_TYPE => $testingTypeManager,
@@ -437,7 +437,7 @@ public function testReplace_Uninstalled() {
    * Note that some metadata changes between versions -- the original has
    * file="oddball", and the upgrade has file="newextension".
    */
-  public function testReplace_Installed() {
+  public function testReplace_Installed(): void {
     $testingTypeManager = $this->getMockBuilder('CRM_Extension_Manager_Interface')->getMock();
     $manager = $this->_createManager([
       self::TESTING_TYPE => $testingTypeManager,
@@ -467,7 +467,7 @@ public function testReplace_Installed() {
     $this->assertDBQuery('newextension', 'SELECT file FROM civicrm_extension WHERE full_name ="test.whiz.bang"');
   }
 
-  public function testComponentExtensionSync() {
+  public function testComponentExtensionSync(): void {
     CRM_Core_BAO_ConfigSetting::enableComponent('CiviCampaign');
     $this->assertEquals(CRM_Extension_Manager::STATUS_INSTALLED, CRM_Extension_System::singleton()->getManager()->getStatus('civi_campaign'));
     CRM_Core_BAO_ConfigSetting::disableComponent('CiviCampaign');
@@ -486,7 +486,7 @@ public function testComponentExtensionSync() {
    * Note that some metadata changes between versions -- the original has
    * file="oddball", and the upgrade has file="newextension".
    */
-  public function testReplace_InstalledMissing() {
+  public function testReplace_InstalledMissing(): void {
     $testingTypeManager = $this->getMockBuilder('CRM_Extension_Manager_Interface')->getMock();
     $manager = $this->_createManager([
       self::TESTING_TYPE => $testingTypeManager,
diff --git a/tests/phpunit/CRM/Extension/MapperTest.php b/tests/phpunit/CRM/Extension/MapperTest.php
index 1f7a955c3e56..c64482dfb371 100644
--- a/tests/phpunit/CRM/Extension/MapperTest.php
+++ b/tests/phpunit/CRM/Extension/MapperTest.php
@@ -45,44 +45,44 @@ public function setUp(): void {
     $this->mapperWithSlash = new CRM_Extension_Mapper($this->containerWithSlash);
   }
 
-  public function testClassToKey() {
+  public function testClassToKey(): void {
     $this->assertEquals("test.foo.bar", $this->mapper->classToKey('test_foo_bar'));
   }
 
-  public function testClassToPath() {
+  public function testClassToPath(): void {
     $this->assertEquals("{$this->basedir}/weird/foobar/oddball.php", $this->mapper->classToPath('test_foo_bar'));
   }
 
-  public function testIsExtensionClass() {
+  public function testIsExtensionClass(): void {
     $this->assertTrue($this->mapper->isExtensionClass('test_foo_bar'));
     $this->assertFalse($this->mapper->isExtensionClass('test.foo.bar'));
     $this->assertFalse($this->mapper->isExtensionClass('CRM_Core_DAO'));
   }
 
-  public function testIsExtensionKey() {
+  public function testIsExtensionKey(): void {
     $this->assertFalse($this->mapper->isExtensionKey('test_foo_bar'));
     $this->assertTrue($this->mapper->isExtensionKey('test.foo.bar'));
     $this->assertFalse($this->mapper->isExtensionKey('CRM_Core_DAO'));
   }
 
-  public function testGetTemplateName() {
+  public function testGetTemplateName(): void {
     $this->assertEquals("oddball.tpl", $this->mapper->getTemplateName('test_foo_bar'));
   }
 
-  public function testGetTemplatePath() {
+  public function testGetTemplatePath(): void {
     $this->assertEquals("{$this->basedir}/weird/foobar/templates", $this->mapper->getTemplatePath('test_foo_bar'));
   }
 
-  public function testKeyToClass() {
+  public function testKeyToClass(): void {
     $this->assertEquals("test_foo_bar", $this->mapper->keyToClass('test.foo.bar'));
   }
 
-  public function testKeyToPath() {
+  public function testKeyToPath(): void {
     $this->assertEquals("{$this->basedir}/weird/foobar/oddball.php", $this->mapper->classToPath('test.foo.bar'));
     $this->assertEquals("{$this->basedir2}/weird/foobar/oddball.php", $this->mapperWithSlash->classToPath('test.foo.bar'));
   }
 
-  public function testKeyToBasePath() {
+  public function testKeyToBasePath(): void {
     $this->assertEquals("{$this->basedir}/weird/foobar", $this->mapper->keyToBasePath('test.foo.bar'));
     $this->assertEquals("{$this->basedir2}/weird/foobar", $this->mapperWithSlash->keyToBasePath('test.foo.bar'));
 
@@ -90,7 +90,7 @@ public function testKeyToBasePath() {
     $this->assertEquals(rtrim($civicrm_root, '/'), $this->mapper->keyToBasePath('civicrm'));
   }
 
-  public function testKeyToUrl() {
+  public function testKeyToUrl(): void {
     $this->assertEquals("http://example/basedir/weird/foobar", $this->mapper->keyToUrl('test.foo.bar'));
     $this->assertEquals("http://example/basedir/weird/foobar", $this->mapperWithSlash->keyToUrl('test.foo.bar'));
 
@@ -99,7 +99,7 @@ public function testKeyToUrl() {
     $this->assertEquals(rtrim($config->resourceBase, '/'), $this->mapperWithSlash->keyToUrl('civicrm'));
   }
 
-  public function testGetKeysByPath() {
+  public function testGetKeysByPath(): void {
     $mappers = [
       $this->basedir => $this->mapper,
       $this->basedir2 => $this->mapperWithSlash,
@@ -120,7 +120,7 @@ public function testGetKeysByPath() {
     }
   }
 
-  public function testGetKeysByTag() {
+  public function testGetKeysByTag(): void {
     $this->assertEquals([], $this->mapper->getKeysByTag('big-rock-candy-mountain'));
     $this->assertEquals(['test.foo.bar'], $this->mapper->getKeysByTag('wakka'));
   }
diff --git a/tests/phpunit/CRM/Financial/BAO/FinancialAccountTest.php b/tests/phpunit/CRM/Financial/BAO/FinancialAccountTest.php
index 2b6100a29477..bb634d93f786 100644
--- a/tests/phpunit/CRM/Financial/BAO/FinancialAccountTest.php
+++ b/tests/phpunit/CRM/Financial/BAO/FinancialAccountTest.php
@@ -27,7 +27,7 @@ public function setUp(): void {
   /**
    * Check method add()
    */
-  public function testAdd() {
+  public function testAdd(): void {
     $params = [
       'name' => 'Donations',
       'is_deductible' => 0,
@@ -49,7 +49,7 @@ public function testAdd() {
   /**
    * Check method retrive()
    */
-  public function testRetrieve() {
+  public function testRetrieve(): void {
     $params = [
       'name' => 'Donations',
       'is_deductible' => 0,
@@ -68,7 +68,7 @@ public function testRetrieve() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testDel() {
+  public function testDel(): void {
     $params = [
       'name' => 'Donations',
       'is_deductible' => 0,
@@ -117,7 +117,7 @@ public function testDeleteIfHasContribution(): void {
   /**
    * Check method getAccountingCode()
    */
-  public function testGetAccountingCode() {
+  public function testGetAccountingCode(): void {
     $params = [
       'name' => 'Donations',
       'is_active' => 1,
@@ -134,14 +134,14 @@ public function testGetAccountingCode() {
   /**
    * Test getting financial account for a given financial Type with a particular relationship.
    */
-  public function testGetFinancialAccountByFinancialTypeAndRelationshipBuiltIn() {
+  public function testGetFinancialAccountByFinancialTypeAndRelationshipBuiltIn(): void {
     $this->assertEquals(2, CRM_Financial_BAO_FinancialAccount::getFinancialAccountForFinancialTypeByRelationship(2, 'Income Account is'));
   }
 
   /**
    * Test getting financial account for a given financial Type with a particular relationship with label changed.
    */
-  public function testGetFinancialAccountByFinancialTypeAndRelationshipBuiltInLabel() {
+  public function testGetFinancialAccountByFinancialTypeAndRelationshipBuiltInLabel(): void {
     // change the label
     $optionValue = $this->callAPISuccess('OptionValue', 'get', [
       'option_group_id' => 'account_relationship',
@@ -163,14 +163,14 @@ public function testGetFinancialAccountByFinancialTypeAndRelationshipBuiltInLabe
   /**
    * Test getting financial account for a given financial Type with a particular relationship.
    */
-  public function testGetFinancialAccountByFinancialTypeAndRelationshipBuiltInRefunded() {
+  public function testGetFinancialAccountByFinancialTypeAndRelationshipBuiltInRefunded(): void {
     $this->assertEquals(2, CRM_Financial_BAO_FinancialAccount::getFinancialAccountForFinancialTypeByRelationship(2, 'Credit/Contra Revenue Account is'));
   }
 
   /**
    * Test getting financial account for a given financial Type with a particular relationship with label changed.
    */
-  public function testGetFinancialAccountByFinancialTypeAndRelationshipBuiltInRefundedLabel() {
+  public function testGetFinancialAccountByFinancialTypeAndRelationshipBuiltInRefundedLabel(): void {
     // change the label
     $optionValue = $this->callAPISuccess('OptionValue', 'get', [
       'option_group_id' => 'account_relationship',
@@ -192,14 +192,14 @@ public function testGetFinancialAccountByFinancialTypeAndRelationshipBuiltInRefu
   /**
    * Test getting financial account for a given financial Type with a particular relationship.
    */
-  public function testGetFinancialAccountByFinancialTypeAndRelationshipBuiltInChargeBack() {
+  public function testGetFinancialAccountByFinancialTypeAndRelationshipBuiltInChargeBack(): void {
     $this->assertEquals(2, CRM_Financial_BAO_FinancialAccount::getFinancialAccountForFinancialTypeByRelationship(2, 'Chargeback Account is'));
   }
 
   /**
    * Test getting financial account for a given financial Type with a particular relationship with label changed.
    */
-  public function testGetFinancialAccountByFinancialTypeAndRelationshipBuiltInChargeBackLabel() {
+  public function testGetFinancialAccountByFinancialTypeAndRelationshipBuiltInChargeBackLabel(): void {
     // change the label
     $optionValue = $this->callAPISuccess('OptionValue', 'get', [
       'option_group_id' => 'account_relationship',
@@ -221,7 +221,7 @@ public function testGetFinancialAccountByFinancialTypeAndRelationshipBuiltInChar
   /**
    * Test getting financial account for a given financial Type with a particular relationship.
    */
-  public function testGetFinancialAccountByFinancialTypeAndRelationshipCustomAddedRefunded() {
+  public function testGetFinancialAccountByFinancialTypeAndRelationshipCustomAddedRefunded(): void {
     $financialAccount = $this->callAPISuccess('FinancialAccount', 'create', [
       'name' => 'Refund Account',
       'is_active' => TRUE,
@@ -240,7 +240,7 @@ public function testGetFinancialAccountByFinancialTypeAndRelationshipCustomAdded
   /**
    * Test getting financial account relations for a given financial type.
    */
-  public function testGetFinancialAccountRelations() {
+  public function testGetFinancialAccountRelations(): void {
     $fAccounts = $rAccounts = [];
     $relations = CRM_Financial_BAO_FinancialAccount::getfinancialAccountRelations();
     $links = [
@@ -277,7 +277,7 @@ public function testGetFinancialAccountRelations() {
   /**
    * Test getting deferred financial type.
    */
-  public function testGetDeferredFinancialType() {
+  public function testGetDeferredFinancialType(): void {
     $result = $this->_createDeferredFinancialAccount();
     $financialTypes = CRM_Financial_BAO_FinancialAccount::getDeferredFinancialType();
     $this->assertTrue(array_key_exists($result, $financialTypes), "The financial type created does not have a deferred account relationship");
@@ -286,7 +286,7 @@ public function testGetDeferredFinancialType() {
   /**
    * Test getting financial account for a given financial Type with a particular relationship.
    */
-  public function testValidateFinancialAccount() {
+  public function testValidateFinancialAccount(): void {
     // Create a record with financial item having financial account as Event Fee.
     $this->createPartiallyPaidParticipantOrder();
     $financialAccounts = CRM_Contribute_PseudoConstant::financialAccount();
@@ -303,7 +303,7 @@ public function testValidateFinancialAccount() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testcheckFinancialTypeHasDeferred() {
+  public function testcheckFinancialTypeHasDeferred(): void {
     Civi::settings()->set('deferred_revenue_enabled', TRUE);
     $params = [];
     $valid = CRM_Financial_BAO_FinancialAccount::checkFinancialTypeHasDeferred($params);
@@ -367,7 +367,7 @@ public function testcheckFinancialTypeHasDeferred() {
   /**
    * Test testGetAllDeferredFinancialAccount.
    */
-  public function testGetAllDeferredFinancialAccount() {
+  public function testGetAllDeferredFinancialAccount(): void {
     $financialAccount = CRM_Financial_BAO_FinancialAccount::getAllDeferredFinancialAccount();
     // The two deferred financial accounts which are created by default.
     $expected = [
@@ -384,7 +384,7 @@ public function testGetAllDeferredFinancialAccount() {
   /**
    * CRM-20037: Test balance due amount, if contribution is done using deferred Financial Type
    */
-  public function testBalanceDueIfDeferredRevenueEnabled() {
+  public function testBalanceDueIfDeferredRevenueEnabled(): void {
     Civi::settings()->set('deferred_revenue_enabled', TRUE);
     $deferredFinancialTypeID = $this->_createDeferredFinancialAccount();
 
diff --git a/tests/phpunit/CRM/Financial/BAO/FinancialTypeAccountTest.php b/tests/phpunit/CRM/Financial/BAO/FinancialTypeAccountTest.php
index 43ded2fa2372..72e9a8b6f561 100644
--- a/tests/phpunit/CRM/Financial/BAO/FinancialTypeAccountTest.php
+++ b/tests/phpunit/CRM/Financial/BAO/FinancialTypeAccountTest.php
@@ -23,7 +23,7 @@ public function setUp(): void {
   /**
    * Check method add()
    */
-  public function testAdd() {
+  public function testAdd(): void {
     list($financialAccount, $financialType, $financialAccountType) = $this->createFinancialAccount(
       'Revenue',
       'Income Account is'
@@ -41,7 +41,7 @@ public function testAdd() {
   /**
    * Check method retrieve()
    */
-  public function testRetrieve() {
+  public function testRetrieve(): void {
     list($financialAccount, $financialType, $financialAccountType) = $this->createFinancialAccount(
       'Asset',
       'Asset Account is'
@@ -63,7 +63,7 @@ public function testRetrieve() {
   /**
    * Check method getInstrumentFinancialAccount()
    */
-  public function testGetInstrumentFinancialAccount() {
+  public function testGetInstrumentFinancialAccount(): void {
     $paymentInstrumentValue = 1;
     list($financialAccount, $financialType, $financialAccountType) = $this->createFinancialAccount(
       'Asset'
@@ -90,7 +90,7 @@ public function testGetInstrumentFinancialAccount() {
   /**
    * Test validate account relationship with financial account type.
    */
-  public function testValidateRelationship() {
+  public function testValidateRelationship(): void {
     $params = ['labelColumn' => 'name'];
     $financialAccount = CRM_Core_PseudoConstant::get('CRM_Financial_DAO_FinancialAccount', 'financial_account_type_id', $params);
     $accountRelationships = CRM_Core_PseudoConstant::get('CRM_Financial_DAO_EntityFinancialAccount', 'account_relationship', $params);
diff --git a/tests/phpunit/CRM/Financial/BAO/PaymentProcessorTest.php b/tests/phpunit/CRM/Financial/BAO/PaymentProcessorTest.php
index fafef3ef7c29..4ca0f0d9a560 100644
--- a/tests/phpunit/CRM/Financial/BAO/PaymentProcessorTest.php
+++ b/tests/phpunit/CRM/Financial/BAO/PaymentProcessorTest.php
@@ -20,7 +20,7 @@ class CRM_Financial_BAO_PaymentProcessorTest extends CiviUnitTestCase {
   /**
    * Check method create()
    */
-  public function testGetCreditCards() {
+  public function testGetCreditCards(): void {
     $params = [
       'name' => 'API_Test_PP_Type',
       'title' => 'API Test Payment Processor Type',
@@ -51,7 +51,7 @@ public function testGetCreditCards() {
    * @throws \CRM_Core_Exception
    * @throws \Civi\API\Exception\UnauthorizedException
    */
-  public function testGetProcessors() {
+  public function testGetProcessors(): void {
     $testProcessor = $this->dummyProcessorCreate();
     $testProcessorID = $testProcessor->getID();
     $liveProcessorID = $testProcessorID + 1;
@@ -90,7 +90,7 @@ public function testGetProcessors() {
   /**
    * Test the Manual processor supports 'NoEmailProvided'
    */
-  public function testManualProcessorSupportsNoEmailProvided() {
+  public function testManualProcessorSupportsNoEmailProvided(): void {
     $processors = CRM_Financial_BAO_PaymentProcessor::getPaymentProcessors(['NoEmailProvided']);
     $found = FALSE;
     foreach ($processors as $processor) {
diff --git a/tests/phpunit/CRM/Financial/BAO/PaymentProcessorTypeTest.php b/tests/phpunit/CRM/Financial/BAO/PaymentProcessorTypeTest.php
index 68b3e2be70e6..a8def20da0a6 100644
--- a/tests/phpunit/CRM/Financial/BAO/PaymentProcessorTypeTest.php
+++ b/tests/phpunit/CRM/Financial/BAO/PaymentProcessorTypeTest.php
@@ -18,7 +18,7 @@ class CRM_Financial_BAO_PaymentProcessorTypeTest extends CiviUnitTestCase {
   /**
    * Check method create()
    */
-  public function testCreate() {
+  public function testCreate(): void {
     $params = [
       'name' => 'Test_Payment_Processor',
       'title' => 'Test Payment Processor',
@@ -39,7 +39,7 @@ public function testCreate() {
   /**
    * Check method retrieve()
    */
-  public function testRetrieve() {
+  public function testRetrieve(): void {
     $params = [
       'name' => 'Test_Retrieve_Payment_Processor',
       'title' => 'Test Retrieve Payment Processor',
@@ -55,7 +55,7 @@ public function testRetrieve() {
   /**
    * Check method setIsActive()
    */
-  public function testSetIsActive() {
+  public function testSetIsActive(): void {
     $params = [
       'name' => 'Test_Set_Payment_Processor',
       'title' => 'Test Set Payment Processor',
@@ -81,7 +81,7 @@ public function testSetIsActive() {
   /**
    * Check method getDefault()
    */
-  public function testGetDefault() {
+  public function testGetDefault(): void {
     $params = ['is_default' => 1];
     $defaults = [];
     $result = CRM_Financial_BAO_PaymentProcessorType::retrieve($params, $defaults);
@@ -93,7 +93,7 @@ public function testGetDefault() {
   /**
    * Check method del()
    */
-  public function testDel() {
+  public function testDel(): void {
     $params = [
       'name' => 'Test_Del_Payment_Processor',
       'title' => 'Test Del Payment Processor',
diff --git a/tests/phpunit/CRM/Group/Page/AjaxTest.php b/tests/phpunit/CRM/Group/Page/AjaxTest.php
index 8ea08a099021..398e84f1dda6 100644
--- a/tests/phpunit/CRM/Group/Page/AjaxTest.php
+++ b/tests/phpunit/CRM/Group/Page/AjaxTest.php
@@ -148,7 +148,7 @@ public function testGroupListViewAllContacts(): void {
    *
    * FIXME permissions to edit groups can only be determined by the links, which is ridiculously long
    */
-  public function testGroupEditWithAndWithoutPermission() {
+  public function testGroupEditWithAndWithoutPermission(): void {
     $this->setPermissionAndRequest('view all contacts');
     $params = $this->_params;
     $groups = CRM_Contact_BAO_Group::getGroupListSelector($params);
@@ -170,7 +170,7 @@ public function testGroupEditWithAndWithoutPermission() {
    * Without setting params the default is both enabled & disabled
    * (if you do set default it is enabled only)
    */
-  public function testGroupListViewAllContactsFoundTitle() {
+  public function testGroupListViewAllContactsFoundTitle(): void {
     $this->_params['title'] = 'p';
     $this->setPermissionAndRequest(['view all contacts', 'edit groups']);
     $params = $this->_params;
@@ -183,7 +183,7 @@ public function testGroupListViewAllContactsFoundTitle() {
   /**
    * Retrieve groups as 'view all contacts'
    */
-  public function testGroupListViewAllContactsNotFoundTitle() {
+  public function testGroupListViewAllContactsNotFoundTitle(): void {
     $this->_params['title'] = 'z';
     $this->setPermissionAndRequest('view all contacts');
     $params = $this->_params;
@@ -194,7 +194,7 @@ public function testGroupListViewAllContactsNotFoundTitle() {
   /**
    * Retrieve groups as 'edit all contacts'
    */
-  public function testGroupListEditAllContacts() {
+  public function testGroupListEditAllContacts(): void {
     $this->setPermissionAndRequest(['edit all contacts', 'edit groups']);
     $params = $this->_params;
     $groups = CRM_Contact_BAO_Group::getGroupListSelector($params);
@@ -206,7 +206,7 @@ public function testGroupListEditAllContacts() {
   /**
    * Retrieve groups as 'view all contacts'
    */
-  public function testGroupListViewAllContactsEnabled() {
+  public function testGroupListViewAllContactsEnabled(): void {
     $this->_params['status'] = 1;
     $this->setPermissionAndRequest(['view all contacts', 'edit groups']);
     $params = $this->_params;
@@ -219,7 +219,7 @@ public function testGroupListViewAllContactsEnabled() {
   /**
    * Retrieve groups as 'view all contacts'
    */
-  public function testGroupListViewAllContactsDisabled() {
+  public function testGroupListViewAllContactsDisabled(): void {
     $this->_params['status'] = 2;
     $this->setPermissionAndRequest(['view all contacts', 'edit groups']);
     $params = $this->_params;
@@ -232,7 +232,7 @@ public function testGroupListViewAllContactsDisabled() {
   /**
    * Retrieve groups as 'view all contacts'
    */
-  public function testGroupListViewAllContactsDisabledNotFoundTitle() {
+  public function testGroupListViewAllContactsDisabledNotFoundTitle(): void {
     $this->_params['status'] = 2;
     $this->_params['title'] = 'n';
     $this->setPermissionAndRequest(['view all contacts', 'edit groups']);
@@ -245,7 +245,7 @@ public function testGroupListViewAllContactsDisabledNotFoundTitle() {
   /**
    * Retrieve groups as 'view all contacts'
    */
-  public function testGroupListViewAllContactsDisabledFoundTitle() {
+  public function testGroupListViewAllContactsDisabledFoundTitle(): void {
     $this->_params['status'] = 2;
     $this->_params['title'] = 'p';
     $this->setPermissionAndRequest(['view all contacts', 'edit groups']);
@@ -258,7 +258,7 @@ public function testGroupListViewAllContactsDisabledFoundTitle() {
   /**
    * Retrieve groups as 'view all contacts'
    */
-  public function testGroupListViewAllContactsAll() {
+  public function testGroupListViewAllContactsAll(): void {
     $this->_params['status'] = 3;
     $this->setPermissionAndRequest(['view all contacts', 'edit groups']);
     $params = $this->_params;
@@ -273,7 +273,7 @@ public function testGroupListViewAllContactsAll() {
   /**
    * Retrieve groups as 'view all contacts'
    */
-  public function testGroupListAccessCiviCRM() {
+  public function testGroupListAccessCiviCRM(): void {
     $this->setPermissionAndRequest('access CiviCRM');
     $permissionClause = CRM_Contact_BAO_Group::getPermissionClause();
     $this->assertEquals('1 = 0', $permissionClause);
@@ -286,7 +286,7 @@ public function testGroupListAccessCiviCRM() {
   /**
    * Retrieve groups as 'view all contacts'
    */
-  public function testGroupListAccessCiviCRMEnabled() {
+  public function testGroupListAccessCiviCRMEnabled(): void {
     $this->_params['status'] = 1;
     $this->setPermissionAndRequest('access CiviCRM');
     $params = $this->_params;
@@ -298,7 +298,7 @@ public function testGroupListAccessCiviCRMEnabled() {
   /**
    * Retrieve groups as 'view all contacts'
    */
-  public function testGroupListAccessCiviCRMDisabled() {
+  public function testGroupListAccessCiviCRMDisabled(): void {
     $this->_params['status'] = 2;
     $this->setPermissionAndRequest('access CiviCRM');
     $params = $this->_params;
@@ -310,7 +310,7 @@ public function testGroupListAccessCiviCRMDisabled() {
   /**
    * Retrieve groups as 'view all contacts'
    */
-  public function testGroupListAccessCiviCRMAll() {
+  public function testGroupListAccessCiviCRMAll(): void {
     $this->_params['status'] = 2;
     $this->setPermissionAndRequest('access CiviCRM');
     $params = $this->_params;
@@ -322,7 +322,7 @@ public function testGroupListAccessCiviCRMAll() {
   /**
    * Retrieve groups as 'view all contacts'
    */
-  public function testGroupListAccessCiviCRMFound() {
+  public function testGroupListAccessCiviCRMFound(): void {
     $this->_params['title'] = 'p';
     $this->setPermissionAndRequest('access CiviCRM');
     $params = $this->_params;
@@ -334,7 +334,7 @@ public function testGroupListAccessCiviCRMFound() {
   /**
    * Retrieve groups as 'view all contacts'
    */
-  public function testGroupListAccessCiviCRMNotFound() {
+  public function testGroupListAccessCiviCRMNotFound(): void {
     $this->_params['title'] = 'z';
     $this->setPermissionAndRequest('access CiviCRM');
     $params = $this->_params;
@@ -343,7 +343,7 @@ public function testGroupListAccessCiviCRMNotFound() {
     $this->assertEquals(0, $groups['recordsTotal'], 'Total returned should be accurate based on permissions');
   }
 
-  public function testTraditionalACL() {
+  public function testTraditionalACL(): void {
     $this->setupACL();
     $this->setPermissionAndRequest('edit groups');
     $params = $this->_params;
@@ -353,7 +353,7 @@ public function testTraditionalACL() {
     $this->assertEquals('pick-me-active', $groups['data'][0]['title']);
   }
 
-  public function testTraditionalACLNotFoundTitle() {
+  public function testTraditionalACLNotFoundTitle(): void {
     $this->_params['title'] = 'n';
     $this->setupACL();
     $params = $this->_params;
@@ -362,7 +362,7 @@ public function testTraditionalACLNotFoundTitle() {
     $this->assertEquals(0, $groups['recordsTotal'], 'Total needs to be set correctly');
   }
 
-  public function testTraditionalACLFoundTitle() {
+  public function testTraditionalACLFoundTitle(): void {
     $this->_params['title'] = 'p';
     $this->setupACL();
     $this->setPermissionAndRequest('edit groups');
@@ -374,7 +374,7 @@ public function testTraditionalACLFoundTitle() {
     $this->assertEquals('pick-me-disabled', $groups['data'][1]['title']);
   }
 
-  public function testTraditionalACLDisabled() {
+  public function testTraditionalACLDisabled(): void {
     $this->_params['status'] = 2;
     $this->setupACL();
     $this->setPermissionAndRequest('edit groups');
@@ -385,7 +385,7 @@ public function testTraditionalACLDisabled() {
     $this->assertEquals('pick-me-disabled', $groups['data'][0]['title']);
   }
 
-  public function testTraditionalACLDisabledFoundTitle() {
+  public function testTraditionalACLDisabledFoundTitle(): void {
     $this->_params['status'] = 2;
     $this->_params['title'] = 'p';
     $this->setupACL();
@@ -397,7 +397,7 @@ public function testTraditionalACLDisabledFoundTitle() {
     $this->assertEquals('pick-me-disabled', $groups['data'][0]['title']);
   }
 
-  public function testTraditionalACLDisabledNotFoundTitle() {
+  public function testTraditionalACLDisabledNotFoundTitle(): void {
     $this->_params['status'] = 2;
     $this->_params['title'] = 'n';
     $this->setupACL();
@@ -407,7 +407,7 @@ public function testTraditionalACLDisabledNotFoundTitle() {
     $this->assertEquals(0, $groups['recordsTotal'], 'Total needs to be set correctly');
   }
 
-  public function testTraditionalACLEnabled() {
+  public function testTraditionalACLEnabled(): void {
     $this->_params['status'] = 1;
     $this->setupACL();
     $this->setPermissionAndRequest('edit groups');
@@ -418,7 +418,7 @@ public function testTraditionalACLEnabled() {
     $this->assertEquals('pick-me-active', $groups['data'][0]['title']);
   }
 
-  public function testTraditionalACLAll() {
+  public function testTraditionalACLAll(): void {
     $this->_params['status'] = 3;
     $this->setupACL();
     $this->setPermissionAndRequest('edit groups');
@@ -433,7 +433,7 @@ public function testTraditionalACLAll() {
   /**
    * ACL Group hook.
    */
-  public function testGroupListAclGroupHookDisabled() {
+  public function testGroupListAclGroupHookDisabled(): void {
     $this->_params['status'] = 2;
     $this->setHookAndRequest(['access CiviCRM', 'edit groups'], 'hook_civicrm_aclGroup');
     $params = $this->_params;
@@ -446,7 +446,7 @@ public function testGroupListAclGroupHookDisabled() {
   /**
    * ACL Group hook.
    */
-  public function testGroupListAclGroupHookDisabledFound() {
+  public function testGroupListAclGroupHookDisabledFound(): void {
     $this->_params['status'] = 2;
     $this->_params['title'] = 'p';
     $this->setHookAndRequest(['access CiviCRM', 'edit groups'], 'hook_civicrm_aclGroup');
@@ -460,7 +460,7 @@ public function testGroupListAclGroupHookDisabledFound() {
   /**
    * ACL Group hook.
    */
-  public function testGroupListAclGroupHookDisabledNotFound() {
+  public function testGroupListAclGroupHookDisabledNotFound(): void {
     $this->_params['status'] = 2;
     $this->_params['title'] = 'n';
     $this->setHookAndRequest('access CiviCRM', 'hook_civicrm_aclGroup');
@@ -473,7 +473,7 @@ public function testGroupListAclGroupHookDisabledNotFound() {
   /**
    * ACL Group hook.
    */
-  public function testGroupListAclGroupHook() {
+  public function testGroupListAclGroupHook(): void {
     $this->setHookAndRequest(['access CiviCRM', 'edit groups'], 'hook_civicrm_aclGroup');
     $params = $this->_params;
     $groups = CRM_Contact_BAO_Group::getGroupListSelector($params);
@@ -485,7 +485,7 @@ public function testGroupListAclGroupHook() {
   /**
    * ACL Group hook.
    */
-  public function testGroupListAclGroupHookTitleNotFound() {
+  public function testGroupListAclGroupHookTitleNotFound(): void {
     $this->_params['title'] = 'n';
     $this->setHookAndRequest('access CiviCRM', 'hook_civicrm_aclGroup');
     $params = $this->_params;
@@ -497,7 +497,7 @@ public function testGroupListAclGroupHookTitleNotFound() {
   /**
    * ACL Group hook.
    */
-  public function testGroupListAclGroupHookTitleFound() {
+  public function testGroupListAclGroupHookTitleFound(): void {
     $this->_params['title'] = 'p';
     $this->setHookAndRequest(['access CiviCRM', 'edit groups'], 'hook_civicrm_aclGroup');
     $params = $this->_params;
@@ -511,7 +511,7 @@ public function testGroupListAclGroupHookTitleFound() {
   /**
    * ACL Group hook.
    */
-  public function testGroupListAclGroupHookAll() {
+  public function testGroupListAclGroupHookAll(): void {
     $this->_params['status'] = 3;
     $this->setHookAndRequest(['access CiviCRM', 'edit groups'], 'hook_civicrm_aclGroup');
     $params = $this->_params;
@@ -525,7 +525,7 @@ public function testGroupListAclGroupHookAll() {
   /**
    * ACL Group hook.
    */
-  public function testGroupListAclGroupHookEnabled() {
+  public function testGroupListAclGroupHookEnabled(): void {
     $this->_params['status'] = 1;
     $this->setHookAndRequest(['access CiviCRM', 'edit groups'], 'hook_civicrm_aclGroup');
     $params = $this->_params;
@@ -540,7 +540,7 @@ public function testGroupListAclGroupHookEnabled() {
    *
    * It takes forever, especially if you have lots of smart groups.
    */
-  public function testGroupDontRegenerateSmartGroups() {
+  public function testGroupDontRegenerateSmartGroups(): void {
     // Create a contact.
     $firstName = 'Tweak';
     $lastName = 'Octonaut';
@@ -685,7 +685,7 @@ public function hook_civicrm_aclGroup($type, $contactID, $tableName, &$allGroups
     }
   }
 
-  public function testEditAllGroupsACL() {
+  public function testEditAllGroupsACL(): void {
     $this->setupEditAllGroupsACL();
     $params = $this->_params;
     $groups = CRM_Contact_BAO_Group::getGroupListSelector($params);
diff --git a/tests/phpunit/CRM/Logging/SchemaTest.php b/tests/phpunit/CRM/Logging/SchemaTest.php
index 769fbd89fadd..b71f80375f7f 100644
--- a/tests/phpunit/CRM/Logging/SchemaTest.php
+++ b/tests/phpunit/CRM/Logging/SchemaTest.php
@@ -145,7 +145,7 @@ public function alterLogTables(&$logTableSpec) {
    *
    * (At point of writing this the modification was leaking to the mailing table).
    */
-  public function testTriggers() {
+  public function testTriggers(): void {
     $customGroup = $this->entityCustomGroupWithSingleFieldCreate('Contact', 'ContactTest....');
     Civi::service('sql_triggers')->rebuild();
     $log_table = CRM_Core_DAO::executeQuery("SHOW TRIGGERS WHERE `Trigger` LIKE 'civicrm_value_contact_{$customGroup['custom_group_id']}_after_insert%'");
@@ -160,7 +160,7 @@ public function testTriggers() {
   /**
    * Test that autoincrement keys are handled sensibly in logging table reconciliation.
    */
-  public function testAutoIncrementNonIdColumn() {
+  public function testAutoIncrementNonIdColumn(): void {
     CRM_Core_DAO::executeQuery("CREATE TABLE `civicrm_test_table` (
       test_id  int(10) unsigned NOT NULL AUTO_INCREMENT,
       PRIMARY KEY (`test_id`)
@@ -212,7 +212,7 @@ public function testAutoIncrementNonIdColumn() {
   /**
    * Test logging trigger definition
    */
-  public function testTriggerInfo() {
+  public function testTriggerInfo(): void {
     $info = [];
     $schema = new CRM_Logging_Schema();
     Civi::settings()->set('logging', TRUE);
@@ -281,7 +281,7 @@ public function testColumnInfo(): void {
     $this->assertEquals('date', $ci['test_date']['DATA_TYPE']);
   }
 
-  public function testIndexes() {
+  public function testIndexes(): void {
     $schema = new CRM_Logging_Schema();
     $indexes = $schema->getIndexesForTable('civicrm_contact');
     $this->assertContains('PRIMARY', $indexes);
@@ -290,7 +290,7 @@ public function testIndexes() {
     $this->assertContains('index_sort_name', $indexes);
   }
 
-  public function testLengthChange() {
+  public function testLengthChange(): void {
     CRM_Core_DAO::executeQuery("CREATE TABLE `civicrm_test_length_change` (
       test_id int(10) unsigned NOT NULL AUTO_INCREMENT,
       test_integer int(4) NULL,
diff --git a/tests/phpunit/CRM/Mailing/BAO/MailingTest.php b/tests/phpunit/CRM/Mailing/BAO/MailingTest.php
index 9af4831d169a..c6b82883f3bd 100644
--- a/tests/phpunit/CRM/Mailing/BAO/MailingTest.php
+++ b/tests/phpunit/CRM/Mailing/BAO/MailingTest.php
@@ -163,7 +163,7 @@ public function testMailingIncludePreviousMailingExcludeGroup(): void {
   /**
    * Test verify that a disabled mailing group doesn't prvent access to the mailing generated with the group.
    */
-  public function testGetMailingDisabledGroup() {
+  public function testGetMailingDisabledGroup(): void {
     $this->prepareForACLs();
     $this->createLoggedInUser();
     // create hook to build ACL where clause which choses $this->allowedContactId as the only contact to be considered as mail recipient
@@ -408,7 +408,7 @@ public function testGetRecipientsEmailGroupIncludeExclude(): void {
   /**
    * Test That No BUlk Emails User Optt Out is resepected when constructing a mailing
    */
-  public function testGetReceipientNoBulkEmails() {
+  public function testGetReceipientNoBulkEmails(): void {
     // Set up groups; 3 standard, 4 smart
     $groupIDs = [];
     $params = [
@@ -451,7 +451,7 @@ public function testGetReceipientNoBulkEmails() {
   /**
    * Test CRM_Mailing_BAO_Mailing::getRecipients() on sms mode
    */
-  public function testgetRecipientsSMS() {
+  public function testgetRecipientsSMS(): void {
     // Tests for SMS bulk mailing recipients
     // +CRM-21320 Ensure primary mobile number is selected over non-primary
     // +core/384 Ensure that a secondary mobile number is selected if the primary can not receive SMS
@@ -582,7 +582,7 @@ public function testgetRecipientsSMS() {
    *  1. In the first call we will modify the mailing filter to include only deceased recipients
    *  2. In the second call we will check if only deceased recipient is populated in MailingRecipient table
    */
-  public function testAlterMailingRecipientsHook() {
+  public function testAlterMailingRecipientsHook(): void {
     $groupID = $this->groupCreate();
     $this->tagCreate(['name' => 'Tagged']);
 
diff --git a/tests/phpunit/CRM/Mailing/BAO/QueryTest.php b/tests/phpunit/CRM/Mailing/BAO/QueryTest.php
index 125f4de936e5..65a43ad1c6cf 100644
--- a/tests/phpunit/CRM/Mailing/BAO/QueryTest.php
+++ b/tests/phpunit/CRM/Mailing/BAO/QueryTest.php
@@ -64,7 +64,7 @@ public function testSearch($fv, $count, $ids, $full) {
   /**
    * CRM-20412: Test accurate count for unique open details
    */
-  public function testOpenedMailingQuery() {
+  public function testOpenedMailingQuery(): void {
 
     $this->loadXMLDataSet(dirname(__FILE__) . '/queryDataset.xml');
     // ensure that total unique opened mail count is same while
@@ -79,7 +79,7 @@ public function testOpenedMailingQuery() {
   /**
    * CRM-21194: Test accurate count for unique trackable URLs
    */
-  public function testTrackableUrlMailingQuery() {
+  public function testTrackableUrlMailingQuery(): void {
     $this->loadXMLDataSet(dirname(__FILE__) . '/queryDataset.xml');
 
     // ensure that total unique clicked mail count is same while
diff --git a/tests/phpunit/CRM/Mailing/BAO/SpoolTest.php b/tests/phpunit/CRM/Mailing/BAO/SpoolTest.php
index 9cd504024dc0..7bf32bcd60a1 100644
--- a/tests/phpunit/CRM/Mailing/BAO/SpoolTest.php
+++ b/tests/phpunit/CRM/Mailing/BAO/SpoolTest.php
@@ -27,7 +27,7 @@ public function tearDown(): void {
   /**
    * Basic send.
    */
-  public function testSend() {
+  public function testSend(): void {
     $contact_params_1 = [
       'first_name' => substr(sha1(rand()), 0, 7),
       'last_name' => 'Anderson',
diff --git a/tests/phpunit/CRM/Mailing/BaseMailingSystemTest.php b/tests/phpunit/CRM/Mailing/BaseMailingSystemTest.php
index 0904541155c5..7884ec4f4818 100644
--- a/tests/phpunit/CRM/Mailing/BaseMailingSystemTest.php
+++ b/tests/phpunit/CRM/Mailing/BaseMailingSystemTest.php
@@ -67,7 +67,7 @@ public function tearDown(): void {
   /**
    * Generate a fully-formatted mailing with standard email headers.
    */
-  public function testBasicHeaders() {
+  public function testBasicHeaders(): void {
     $allMessages = $this->runMailingSuccess([
       'subject' => 'Accidents in cars cause children for {contact.display_name}!',
       'body_text' => 'BEWARE children need regular infusions of toys. Santa knows your {domain.address}. There is no {action.optOutUrl}.',
@@ -93,7 +93,7 @@ public function testBasicHeaders() {
   /**
    * Generate a fully-formatted mailing (with body_text content).
    */
-  public function testText() {
+  public function testText(): void {
     $allMessages = $this->runMailingSuccess([
       'subject' => 'Accidents in cars cause children for {contact.display_name}!',
       'body_text' => 'BEWARE children need regular infusions of toys. Santa knows your {domain.address}. There is no {action.optOutUrl}.',
@@ -123,7 +123,7 @@ public function testText() {
   /**
    * Generate a fully-formatted mailing (with body_html content).
    */
-  public function testHtmlWithOpenTracking() {
+  public function testHtmlWithOpenTracking(): void {
     $allMessages = $this->runMailingSuccess([
       'subject' => 'Example Subject',
       'body_html' => '<p>You can go to <a href="http://example.net/first?{contact.checksum}">Google</a> or <a href="{action.optOutUrl}">opt out</a>.</p>',
@@ -180,7 +180,7 @@ public function testHtmlWithOpenTracking() {
   /**
    * Generate a fully-formatted mailing (with body_html content).
    */
-  public function testHtmlWithOpenAndUrlTracking() {
+  public function testHtmlWithOpenAndUrlTracking(): void {
     $allMessages = $this->runMailingSuccess([
       'subject' => 'Example Subject',
       'body_html' => '<p>You can go to <a href="http://example.net">Google</a> or <a href="{action.optOutUrl}">opt out</a>.</p>',
diff --git a/tests/phpunit/CRM/Mailing/Form/Task/AdhocMailingTest.php b/tests/phpunit/CRM/Mailing/Form/Task/AdhocMailingTest.php
index 7d196ada74f9..267bb380c08b 100644
--- a/tests/phpunit/CRM/Mailing/Form/Task/AdhocMailingTest.php
+++ b/tests/phpunit/CRM/Mailing/Form/Task/AdhocMailingTest.php
@@ -22,7 +22,7 @@ class CRM_Mailing_Form_Task_AdhocMailingTest extends CiviUnitTestCase {
    * @throws \CRM_Core_Exception
    * @throws \Exception
    */
-  public function testCreateHiddenGroupFromSearchBuilder() {
+  public function testCreateHiddenGroupFromSearchBuilder(): void {
     $this->createLoggedInUser();
     $formValues = [
       'entryURL' => 'http://dmaster.local/civicrm/contact/search/builder?reset=1',
diff --git a/tests/phpunit/CRM/Mailing/MailStoreTest.php b/tests/phpunit/CRM/Mailing/MailStoreTest.php
index 4472ac2edc2a..4c60427f2259 100644
--- a/tests/phpunit/CRM/Mailing/MailStoreTest.php
+++ b/tests/phpunit/CRM/Mailing/MailStoreTest.php
@@ -24,7 +24,7 @@ public function tearDown(): void {
   /**
    * Create an example store (maildir) using default behaviors (no hooks).
    */
-  public function testMaildirBasic() {
+  public function testMaildirBasic(): void {
     $this->createMaildirSettings([
       'name' => __FUNCTION__,
     ]);
@@ -35,7 +35,7 @@ public function testMaildirBasic() {
   /**
    * Create an example store (maildir) and change the driver via hook.
    */
-  public function testMaildirHook() {
+  public function testMaildirHook(): void {
     // This hook swaps out the implementation used for 'Maildir' stores.
     Civi::dispatcher()
       ->addListener('hook_civicrm_alterMailStore', function ($e) {
diff --git a/tests/phpunit/CRM/Mailing/MailingSystemTest.php b/tests/phpunit/CRM/Mailing/MailingSystemTest.php
index 50e49d037397..20d7bd08c4ea 100644
--- a/tests/phpunit/CRM/Mailing/MailingSystemTest.php
+++ b/tests/phpunit/CRM/Mailing/MailingSystemTest.php
@@ -118,19 +118,19 @@ public function testUrlTracking(
     parent::testUrlTracking($inputHtml, $htmlUrlRegex, $textUrlRegex, $params);
   }
 
-  public function testBasicHeaders() {
+  public function testBasicHeaders(): void {
     parent::testBasicHeaders();
   }
 
-  public function testText() {
+  public function testText(): void {
     parent::testText();
   }
 
-  public function testHtmlWithOpenTracking() {
+  public function testHtmlWithOpenTracking(): void {
     parent::testHtmlWithOpenTracking();
   }
 
-  public function testHtmlWithOpenAndUrlTracking() {
+  public function testHtmlWithOpenAndUrlTracking(): void {
     parent::testHtmlWithOpenAndUrlTracking();
   }
 
@@ -138,7 +138,7 @@ public function testHtmlWithOpenAndUrlTracking() {
    * Test to check Activity being created on mailing Job.
    *
    */
-  public function testMailingActivityCreate() {
+  public function testMailingActivityCreate(): void {
     $subject = uniqid('testMailingActivityCreate');
     $this->runMailingSuccess([
       'subject' => $subject,
diff --git a/tests/phpunit/CRM/Mailing/TokensTest.php b/tests/phpunit/CRM/Mailing/TokensTest.php
index 7577ab70bd90..d949c774272d 100644
--- a/tests/phpunit/CRM/Mailing/TokensTest.php
+++ b/tests/phpunit/CRM/Mailing/TokensTest.php
@@ -68,7 +68,7 @@ public function testTokensWithMailingId($inputTemplateFormat, $inputTemplate, $e
   /**
    * Check that mailing-tokens are generated (given a mailing DAO as input).
    */
-  public function testTokensWithMailingObject() {
+  public function testTokensWithMailingObject(): void {
     // We only need one case to see that the mailing-object works as
     // an alternative to the mailing-id.
     $inputTemplateFormat = 'text/plain';
diff --git a/tests/phpunit/CRM/Member/BAO/MembershipLogTest.php b/tests/phpunit/CRM/Member/BAO/MembershipLogTest.php
index d0ebb5479f99..4ec755281541 100644
--- a/tests/phpunit/CRM/Member/BAO/MembershipLogTest.php
+++ b/tests/phpunit/CRM/Member/BAO/MembershipLogTest.php
@@ -114,7 +114,7 @@ public function tearDown(): void {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testDel() {
+  public function testDel(): void {
     list($contactID, $membershipID) = $this->setupMembership();
     CRM_Member_BAO_MembershipLog::deleteRecord(['id' => $membershipID]);
     $this->assertDBNull('CRM_Member_BAO_MembershipLog', $membershipID, 'membership_id',
@@ -130,7 +130,7 @@ public function testDel() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testResetModifiedID() {
+  public function testResetModifiedID(): void {
     list($contactID, $membershipID) = $this->setupMembership();
     CRM_Member_BAO_MembershipLog::resetModifiedID($contactID);
     $this->assertDBNull('CRM_Member_BAO_MembershipLog', $contactID, 'modified_id',
diff --git a/tests/phpunit/CRM/Member/BAO/MembershipStatusTest.php b/tests/phpunit/CRM/Member/BAO/MembershipStatusTest.php
index 0d06eee9f25c..4654dd367181 100644
--- a/tests/phpunit/CRM/Member/BAO/MembershipStatusTest.php
+++ b/tests/phpunit/CRM/Member/BAO/MembershipStatusTest.php
@@ -27,7 +27,7 @@ protected function tearDown(): void {
   /**
    * Check function add()
    */
-  public function testAdd() {
+  public function testAdd(): void {
     $params = [
       'name' => 'added',
       'is_active' => 1,
@@ -45,7 +45,7 @@ public function testAdd() {
   /**
    * @throws \CRM_Core_Exception
    */
-  public function testExpiredDisabled() {
+  public function testExpiredDisabled(): void {
     $this->callAPISuccess('MembershipStatus', 'get', [
       'name' => 'Expired',
       'api.MembershipStatus.create' => ['label' => 'Expiiiired'],
@@ -88,7 +88,7 @@ public function testExpiredDisabled() {
 
   }
 
-  public function testGetMembershipStatusByDate() {
+  public function testGetMembershipStatusByDate(): void {
     $params = [
       'name' => 'Current',
       'is_active' => 1,
@@ -341,7 +341,7 @@ public function statusByDateProvider():array {
     ];
   }
 
-  public function testgetMembershipStatusCurrent() {
+  public function testgetMembershipStatusCurrent(): void {
     $params = [
       'name' => 'Current',
       'is_active' => 1,
diff --git a/tests/phpunit/CRM/Member/BAO/MembershipTest.php b/tests/phpunit/CRM/Member/BAO/MembershipTest.php
index 4368d25acad0..325dc033e990 100644
--- a/tests/phpunit/CRM/Member/BAO/MembershipTest.php
+++ b/tests/phpunit/CRM/Member/BAO/MembershipTest.php
@@ -330,7 +330,7 @@ public function testGetContactMembership(): void {
     $this->contactDelete($contactId);
   }
 
-  public function testGetAllContactMembership() {
+  public function testGetAllContactMembership(): void {
     $lifetimeTypeId = $this->membershipTypeCreate([
       'name' => 'Lifetime',
       'duration_unit' => 'lifetime',
@@ -928,7 +928,7 @@ public function testMembershipUpdateDoesNotDeleteRelatedMembershipsByMistake():
     $this->assertMembershipExists($relatedMembership2['id']);
   }
 
-  public function testRelatedMembershipWithContactReferenceCustomField() {
+  public function testRelatedMembershipWithContactReferenceCustomField(): void {
     $relatedContactId = $this->individualCreate();
     $customContactId = $this->individualCreate();
     $membershipOrganizationId = $this->organizationCreate();
diff --git a/tests/phpunit/CRM/Member/BAO/QueryTest.php b/tests/phpunit/CRM/Member/BAO/QueryTest.php
index 460cb6ac4d74..3a07218945e6 100644
--- a/tests/phpunit/CRM/Member/BAO/QueryTest.php
+++ b/tests/phpunit/CRM/Member/BAO/QueryTest.php
@@ -22,7 +22,7 @@ public function setUp(): void {
    * We want to see the following syntaxes for membership_type_id field handled:
    *   1) membership_type_id => 1
    */
-  public function testConvertEntityFieldSingleValue() {
+  public function testConvertEntityFieldSingleValue(): void {
     $formValues = ['membership_type_id' => 2];
     $params = CRM_Contact_BAO_Query::convertFormValues($formValues, 0, FALSE, NULL, ['membership_type_id']);
     $this->assertEquals(['membership_type_id', '=', 2, 0, 0], $params[0]);
@@ -38,7 +38,7 @@ public function testConvertEntityFieldSingleValue() {
    *
    * The last of these is the format used prior to converting membership_type_id to an entity reference field.
    */
-  public function testConvertEntityFieldMultipleValueEntityRef() {
+  public function testConvertEntityFieldMultipleValueEntityRef(): void {
     $formValues = ['membership_type_id' => '1,2'];
     $params = CRM_Contact_BAO_Query::convertFormValues($formValues, 0, FALSE, NULL, ['membership_type_id']);
     $this->assertEquals(['membership_type_id', 'IN', [1, 2], 0, 0], $params[0]);
@@ -55,7 +55,7 @@ public function testConvertEntityFieldMultipleValueEntityRef() {
    * The last of these is the format used prior to converting membership_type_id to an entity reference field. It will
    * be used by pre-existing smart groups.
    */
-  public function testConvertEntityFieldMultipleValueLegacy() {
+  public function testConvertEntityFieldMultipleValueLegacy(): void {
     $formValues = ['membership_type_id' => [1, 2]];
     $params = CRM_Contact_BAO_Query::convertFormValues($formValues, 0, FALSE, NULL, ['membership_type_id']);
     $this->assertEquals(['membership_type_id', 'IN', [1, 2], 0, 0], $params[0]);
@@ -70,7 +70,7 @@ public function testConvertEntityFieldMultipleValueLegacy() {
    *
    * The convertFormValues function should cope with this until such time as we can rationalise that.
    */
-  public function testConvertEntityFieldMultipleValueEntityRefDoubleRun() {
+  public function testConvertEntityFieldMultipleValueEntityRefDoubleRun(): void {
     $formValues = ['membership_type_id' => '1,2'];
     $params = CRM_Contact_BAO_Query::convertFormValues($formValues, 0, FALSE, NULL, ['membership_type_id']);
     $this->assertEquals(['membership_type_id', 'IN', [1, 2], 0, 0], $params[0]);
diff --git a/tests/phpunit/CRM/Member/Form/MembershipTest.php b/tests/phpunit/CRM/Member/Form/MembershipTest.php
index 45ec1b6a2cd2..059dd6f3ca16 100644
--- a/tests/phpunit/CRM/Member/Form/MembershipTest.php
+++ b/tests/phpunit/CRM/Member/Form/MembershipTest.php
@@ -295,7 +295,7 @@ public function testFormRuleRollingLifetimeEnd(): void {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testFormRulePermanentOverrideWithNoStatus() {
+  public function testFormRulePermanentOverrideWithNoStatus(): void {
     $params = [
       'join_date' => date('Y-m-d'),
       'membership_type_id' => [$this->ids['contact']['organization'], $this->ids['membership_type']['AnnualFixed']],
@@ -308,7 +308,7 @@ public function testFormRulePermanentOverrideWithNoStatus() {
     $this->assertTrue(array_key_exists('status_id', $rc));
   }
 
-  public function testFormRuleUntilDateOverrideWithValidOverrideEndDate() {
+  public function testFormRuleUntilDateOverrideWithValidOverrideEndDate(): void {
     $params = [
       'join_date' => date('Y-m-d'),
       'membership_type_id' => [$this->ids['contact']['organization'], $this->ids['membership_type']['AnnualFixed']],
@@ -364,7 +364,7 @@ public function testFormRuleRollingJoin1MonthFromNow(): void {
   /**
    * Test CRM_Member_Form_Membership::formRule() with a join date of today and a rolling membership type.
    */
-  public function testFormRuleRollingJoinToday() {
+  public function testFormRuleRollingJoinToday(): void {
     $params = [
       'join_date' => date('Y-m-d'),
       'start_date' => '',
@@ -383,7 +383,7 @@ public function testFormRuleRollingJoinToday() {
    *  Test CRM_Member_Form_Membership::formRule() with a join date
    *  of one month ago and a rolling membership type
    */
-  public function testFormRuleRollingJoin1MonthAgo() {
+  public function testFormRuleRollingJoin1MonthAgo(): void {
     $unixNow = time();
     $unix1MAgo = $unixNow - (31 * 24 * 60 * 60);
     $params = [
@@ -403,7 +403,7 @@ public function testFormRuleRollingJoin1MonthAgo() {
   /**
    *  Test CRM_Member_Form_Membership::formRule() with a join date of six months ago and a rolling membership type.
    */
-  public function testFormRuleRollingJoin6MonthsAgo() {
+  public function testFormRuleRollingJoin6MonthsAgo(): void {
     $unixNow = time();
     $unix6MAgo = $unixNow - (180 * 24 * 60 * 60);
     $params = [
@@ -424,7 +424,7 @@ public function testFormRuleRollingJoin6MonthsAgo() {
    *  Test CRM_Member_Form_Membership::formRule() with a join date
    *  of one year+ ago and a rolling membership type
    */
-  public function testFormRuleRollingJoin1YearAgo() {
+  public function testFormRuleRollingJoin1YearAgo(): void {
     $unixNow = time();
     $unix1YAgo = $unixNow - (370 * 24 * 60 * 60);
     $params = [
@@ -445,7 +445,7 @@ public function testFormRuleRollingJoin1YearAgo() {
    *  Test CRM_Member_Form_Membership::formRule() with a join date
    *  of two years ago and a rolling membership type
    */
-  public function testFormRuleRollingJoin2YearsAgo() {
+  public function testFormRuleRollingJoin2YearsAgo(): void {
     $unixNow = time();
     $unix2YAgo = $unixNow - (2 * 365 * 24 * 60 * 60);
     $params = [
@@ -467,7 +467,7 @@ public function testFormRuleRollingJoin2YearsAgo() {
    *
    * The setup is a join date of six months ago and a fixed membership type.
    */
-  public function testFormRuleFixedJoin6MonthsAgo() {
+  public function testFormRuleFixedJoin6MonthsAgo(): void {
     $unixNow = time();
     $unix6MAgo = $unixNow - (180 * 24 * 60 * 60);
     $params = [
diff --git a/tests/phpunit/CRM/Member/Form/Task/BatchTest.php b/tests/phpunit/CRM/Member/Form/Task/BatchTest.php
index 230dd2c0093a..3eb04cffbe80 100644
--- a/tests/phpunit/CRM/Member/Form/Task/BatchTest.php
+++ b/tests/phpunit/CRM/Member/Form/Task/BatchTest.php
@@ -35,7 +35,7 @@ public function tearDown(): void {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testBatchSubmit() {
+  public function testBatchSubmit(): void {
     $form = $this->getFormObject('CRM_Member_Form_Task_Batch');
     $membership1 = $this->contactMembershipCreate(['contact_id' => $this->individualCreate()]);
     $membership2 = $this->contactMembershipCreate(['contact_id' => $this->individualCreate()]);
diff --git a/tests/phpunit/CRM/Member/StatusOverrideTypesTest.php b/tests/phpunit/CRM/Member/StatusOverrideTypesTest.php
index 59f6229671a0..f337471d9be1 100644
--- a/tests/phpunit/CRM/Member/StatusOverrideTypesTest.php
+++ b/tests/phpunit/CRM/Member/StatusOverrideTypesTest.php
@@ -15,31 +15,31 @@
  */
 class CRM_Member_StatusOverrideTypesTest extends CiviUnitTestCase {
 
-  public function testIsOverriddenReturnFalseForNoStatusOverrideType() {
+  public function testIsOverriddenReturnFalseForNoStatusOverrideType(): void {
     $statusOverrideTypes = new CRM_Member_StatusOverrideTypes();
     $isOverridden = $statusOverrideTypes::isOverridden(CRM_Member_StatusOverrideTypes::NO);
     $this->assertFalse($isOverridden);
   }
 
-  public function testIsOverriddenReturnTrueForPermanentStatusOverrideType() {
+  public function testIsOverriddenReturnTrueForPermanentStatusOverrideType(): void {
     $statusOverrideTypes = new CRM_Member_StatusOverrideTypes();
     $isOverridden = $statusOverrideTypes::isOverridden(CRM_Member_StatusOverrideTypes::PERMANENT);
     $this->assertTrue($isOverridden);
   }
 
-  public function testIsOverriddenReturnTrueForUntilDateStatusOverrideType() {
+  public function testIsOverriddenReturnTrueForUntilDateStatusOverrideType(): void {
     $statusOverrideTypes = new CRM_Member_StatusOverrideTypes();
     $isOverridden = $statusOverrideTypes::isOverridden(CRM_Member_StatusOverrideTypes::UNTIL_DATE);
     $this->assertTrue($isOverridden);
   }
 
-  public function testIsNoReturnTrueForNoStatusOverrideType() {
+  public function testIsNoReturnTrueForNoStatusOverrideType(): void {
     $statusOverrideTypes = new CRM_Member_StatusOverrideTypes();
     $isNo = $statusOverrideTypes::isNo(CRM_Member_StatusOverrideTypes::NO);
     $this->assertTrue($isNo);
   }
 
-  public function testIsNoReturnFalseForOtherStatusOverrideType() {
+  public function testIsNoReturnFalseForOtherStatusOverrideType(): void {
     $statusOverrideTypes = new CRM_Member_StatusOverrideTypes();
     $isNo = $statusOverrideTypes::isNo(CRM_Member_StatusOverrideTypes::PERMANENT);
     $this->assertFalse($isNo);
@@ -48,13 +48,13 @@ public function testIsNoReturnFalseForOtherStatusOverrideType() {
     $this->assertFalse($isNo);
   }
 
-  public function testisPermanentReturnTrueForPermanentStatusOverrideType() {
+  public function testisPermanentReturnTrueForPermanentStatusOverrideType(): void {
     $statusOverrideTypes = new CRM_Member_StatusOverrideTypes();
     $isPermanent = $statusOverrideTypes::isPermanent(CRM_Member_StatusOverrideTypes::PERMANENT);
     $this->assertTrue($isPermanent);
   }
 
-  public function testisPermanentReturnFalseForOtherStatusOverrideType() {
+  public function testisPermanentReturnFalseForOtherStatusOverrideType(): void {
     $statusOverrideTypes = new CRM_Member_StatusOverrideTypes();
     $isPermanent = $statusOverrideTypes::isPermanent(CRM_Member_StatusOverrideTypes::NO);
     $this->assertFalse($isPermanent);
@@ -63,13 +63,13 @@ public function testisPermanentReturnFalseForOtherStatusOverrideType() {
     $this->assertFalse($isPermanent);
   }
 
-  public function testisUntilDateReturnTrueForUntilDateStatusOverrideType() {
+  public function testisUntilDateReturnTrueForUntilDateStatusOverrideType(): void {
     $statusOverrideTypes = new CRM_Member_StatusOverrideTypes();
     $isUntilDate = $statusOverrideTypes::isUntilDate(CRM_Member_StatusOverrideTypes::UNTIL_DATE);
     $this->assertTrue($isUntilDate);
   }
 
-  public function testisUntilDateReturnFalseForOtherStatusOverrideType() {
+  public function testisUntilDateReturnFalseForOtherStatusOverrideType(): void {
     $statusOverrideTypes = new CRM_Member_StatusOverrideTypes();
     $isUntilDate = $statusOverrideTypes::isUntilDate(CRM_Member_StatusOverrideTypes::NO);
     $this->assertFalse($isUntilDate);
diff --git a/tests/phpunit/CRM/PCP/BAO/PCPTest.php b/tests/phpunit/CRM/PCP/BAO/PCPTest.php
index 7954a4e45a9d..2f8a25c2f706 100644
--- a/tests/phpunit/CRM/PCP/BAO/PCPTest.php
+++ b/tests/phpunit/CRM/PCP/BAO/PCPTest.php
@@ -29,7 +29,7 @@ public function tearDown(): void {
     parent::tearDown();
   }
 
-  public function testAddPCPBlock() {
+  public function testAddPCPBlock(): void {
 
     $params = $this->pcpBlockParams();
     $pcpBlock = CRM_PCP_BAO_PCPBlock::writeRecord($params);
@@ -50,13 +50,13 @@ public function testAddPCPBlock() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testCreatePCP() {
+  public function testCreatePCP(): void {
     $params = $this->pcpParams();
     $pcpID = $this->createPCPBlock($params);
     $this->getAndCheck($params, $pcpID, 'Pcp');
   }
 
-  public function testAddPCPNoStatus() {
+  public function testAddPCPNoStatus(): void {
     $blockParams = $this->pcpBlockParams();
     $pcpBlock = CRM_PCP_BAO_PCPBlock::writeRecord($blockParams);
 
@@ -79,7 +79,7 @@ public function testAddPCPNoStatus() {
     $this->assertEquals($params['is_active'], $pcp->is_active, 'Check for is_active.');
   }
 
-  public function testDeletePCP() {
+  public function testDeletePCP(): void {
 
     $pcp = CRM_Core_DAO::createTestObject('CRM_PCP_DAO_PCP');
     $pcpId = $pcp->id;
@@ -92,7 +92,7 @@ public function testDeletePCP() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testGetPcpDashboardInfo() {
+  public function testGetPcpDashboardInfo(): void {
     $block = CRM_PCP_BAO_PCPBlock::writeRecord($this->pcpBlockParams());
     $contactID = $this->individualCreate();
     $submitParams = [
@@ -123,7 +123,7 @@ public function testGetPcpDashboardInfo() {
   /**
    * Test that hook_civicrm_links is called.
    */
-  public function testPcpInfoLinksHook() {
+  public function testPcpInfoLinksHook(): void {
     Civi::dispatcher()->addListener('hook_civicrm_links', [$this, 'hookLinks']);
 
     // Reset the cache otherwise our hook will not be called
@@ -170,7 +170,7 @@ public function hookLinks(\Civi\Core\Event\GenericHookEvent $e) {
    * Test that CRM_Contribute_BAO_Contribution::_gatherMessageValues() works
    * with PCP.
    */
-  public function testGatherMessageValuesForPCP() {
+  public function testGatherMessageValuesForPCP(): void {
     // set up a pcp page
     $block = CRM_PCP_BAO_PCPBlock::writeRecord($this->pcpBlockParams());
     // The owner of the pcp, who gets the soft credit
diff --git a/tests/phpunit/CRM/Pledge/BAO/PledgeBlockTest.php b/tests/phpunit/CRM/Pledge/BAO/PledgeBlockTest.php
index 3b0031dd8f16..86452b1e4dea 100644
--- a/tests/phpunit/CRM/Pledge/BAO/PledgeBlockTest.php
+++ b/tests/phpunit/CRM/Pledge/BAO/PledgeBlockTest.php
@@ -35,7 +35,7 @@ protected function setUp(): void {
   /**
    *  create() and deletepledgeblock() method
    */
-  public function testCreateAndDeletePledgeBlock() {
+  public function testCreateAndDeletePledgeBlock(): void {
 
     $pledgeFrequencyUnit = [
       'week' => 1,
@@ -68,7 +68,7 @@ public function testCreateAndDeletePledgeBlock() {
   /**
    * Add() method (add and edit modes of pledge block)
    */
-  public function testAddPledgeBlock() {
+  public function testAddPledgeBlock(): void {
 
     $pledgeFrequencyUnit = [
       'week' => 1,
@@ -117,7 +117,7 @@ public function testAddPledgeBlock() {
   /**
    * Retrieve() and getPledgeBlock() method of  pledge block
    */
-  public function testRetrieveAndGetPledgeBlock() {
+  public function testRetrieveAndGetPledgeBlock(): void {
 
     $pledgeFrequencyUnit = [
       'week' => 1,
diff --git a/tests/phpunit/CRM/Pledge/BAO/PledgePaymentTest.php b/tests/phpunit/CRM/Pledge/BAO/PledgePaymentTest.php
index 6860097c8809..bb1ba71cfe16 100644
--- a/tests/phpunit/CRM/Pledge/BAO/PledgePaymentTest.php
+++ b/tests/phpunit/CRM/Pledge/BAO/PledgePaymentTest.php
@@ -20,7 +20,7 @@ class CRM_Pledge_BAO_PledgePaymentTest extends CiviUnitTestCase {
   /**
    *  Test for Add/Update Pledge Payment.
    */
-  public function testAdd() {
+  public function testAdd(): void {
     $pledge = CRM_Core_DAO::createTestObject('CRM_Pledge_BAO_Pledge');
     $params = [
       'pledge_id' => $pledge->id,
@@ -60,7 +60,7 @@ public function testAdd() {
   /**
    *  Retrieve a payment based on a pledge id = 0
    */
-  public function testRetrieveZeroPledeID() {
+  public function testRetrieveZeroPledeID(): void {
     $payment = CRM_Core_DAO::createTestObject('CRM_Pledge_BAO_PledgePayment');
     $params = ['pledge_id' => 0];
     $defaults = [];
@@ -73,7 +73,7 @@ public function testRetrieveZeroPledeID() {
   /**
    *  Retrieve a payment based on a Null pledge id.
    */
-  public function testRetrieveStringPledgeID() {
+  public function testRetrieveStringPledgeID(): void {
     $payment = CRM_Core_DAO::createTestObject('CRM_Pledge_BAO_PledgePayment');
     $params = ['pledge_id' => 'Test'];
     $defaults = [];
@@ -86,7 +86,7 @@ public function testRetrieveStringPledgeID() {
   /**
    *  Test that payment retrieve wrks based on known pledge id.
    */
-  public function testRetrieveKnownPledgeID() {
+  public function testRetrieveKnownPledgeID(): void {
     $payment = CRM_Core_DAO::createTestObject('CRM_Pledge_BAO_PledgePayment');
     $pledgeId = $payment->pledge_id;
     $params = ['pledge_id' => $pledgeId];
@@ -100,7 +100,7 @@ public function testRetrieveKnownPledgeID() {
   /**
    *  Delete Payments payments for one pledge.
    */
-  public function testDeletePledgePaymentsNormal() {
+  public function testDeletePledgePaymentsNormal(): void {
     $payment = CRM_Core_DAO::createTestObject('CRM_Pledge_BAO_PledgePayment');
     $paymentid = CRM_Pledge_BAO_PledgePayment::deletePayments($payment->pledge_id);
 
@@ -111,7 +111,7 @@ public function testDeletePledgePaymentsNormal() {
   /**
    *  Delete Multiple payments for one pledge.
    */
-  public function testDeletePledgePayments() {
+  public function testDeletePledgePayments(): void {
     $contactId = $this->individualCreate();
     $pledgeId = $this->pledgeCreate(['contact_id' => $contactId]);
     CRM_Pledge_BAO_PledgePayment::deletePayments($pledgeId);
@@ -124,7 +124,7 @@ public function testDeletePledgePayments() {
   /**
    *  Pass Null Id for a payment deletion for one pledge.
    */
-  public function testDeletePledgePaymentsNullId() {
+  public function testDeletePledgePaymentsNullId(): void {
     $payment = CRM_Core_DAO::createTestObject('CRM_Pledge_BAO_PledgePayment');
     $paymentid = CRM_Pledge_BAO_PledgePayment::deletePayments(NULL);
     $this->assertFalse($paymentid, "No payments deleted");
@@ -134,7 +134,7 @@ public function testDeletePledgePaymentsNullId() {
   /**
    *  Pass Zero Id for a payment deletion for one pledge.
    */
-  public function testDeletePaymentsZeroId() {
+  public function testDeletePaymentsZeroId(): void {
     $payment = CRM_Core_DAO::createTestObject('CRM_Pledge_BAO_PledgePayment');
     $paymentid = CRM_Pledge_BAO_PledgePayment::deletePayments(0);
     $result = CRM_Pledge_BAO_Pledge::deletePledge($payment->pledge_id);
@@ -143,7 +143,7 @@ public function testDeletePaymentsZeroId() {
   /**
    *  Test calculateBaseScheduleDate - should give 15th day of month
    */
-  public function testcalculateBaseScheduleDateMonth() {
+  public function testcalculateBaseScheduleDateMonth(): void {
     $params = [
       'scheduled_date' => '20110510',
       'frequency_unit' => 'month',
@@ -158,7 +158,7 @@ public function testcalculateBaseScheduleDateMonth() {
   /**
    *  Test calculateBaseScheduleDate - should give original date
    */
-  public function testcalculateBaseScheduleDateDay() {
+  public function testcalculateBaseScheduleDateDay(): void {
     $params = [
       'scheduled_date' => '20110510',
       'frequency_unit' => 'day',
@@ -174,7 +174,7 @@ public function testcalculateBaseScheduleDateDay() {
    * Test calculateBaseScheduleDateWeek - should give the day in the week as indicated
    * testing each day as this is really the only unit that does anything
    */
-  public function testcalculateBaseScheduleDateWeek() {
+  public function testcalculateBaseScheduleDateWeek(): void {
     $params = [
       'scheduled_date' => '20110510',
       'frequency_unit' => 'week',
@@ -207,7 +207,7 @@ public function testcalculateBaseScheduleDateWeek() {
   /**
    *  Test calculateBaseScheduleDate - should give original date
    */
-  public function testcalculateBaseScheduleDateYear() {
+  public function testcalculateBaseScheduleDateYear(): void {
     $params = [
       'scheduled_date' => '20110510',
       'frequency_unit' => 'year',
@@ -222,7 +222,7 @@ public function testcalculateBaseScheduleDateYear() {
   /**
    *  Test calculateNextScheduledDate - no date provided
    */
-  public function testcalculateNextScheduledDateYear() {
+  public function testcalculateNextScheduledDateYear(): void {
     $params = [
       'scheduled_date' => '20110510',
       'frequency_unit' => 'year',
@@ -238,7 +238,7 @@ public function testcalculateNextScheduledDateYear() {
    *  CRM-18316: To calculate pledge scheduled dates with end of a month.
    *  Test culateNextScheduledDateMonth for months.
    */
-  public function testcalculateNextScheduledDateMonth() {
+  public function testcalculateNextScheduledDateMonth(): void {
     $params = [
       'scheduled_date' => '20110510',
       'frequency_unit' => 'month',
@@ -302,7 +302,7 @@ public function testcalculateNextScheduledDateMonth() {
   /**
    *  Test calculateNextScheduledDate - no date provided
    */
-  public function testcalculateNextScheduledDateYearDateProvided() {
+  public function testcalculateNextScheduledDateYearDateProvided(): void {
     $params = [
       'scheduled_date' => '20110510',
       'frequency_unit' => 'year',
@@ -319,7 +319,7 @@ public function testcalculateNextScheduledDateYearDateProvided() {
    * Check for rounding bugs. NB: this cannot be done in the API, because the
    * API does not call CRM_Contribute_BAO_Contribution::updateRelatedPledge().
    */
-  public function testCreatePledgePaymentForMultipleInstallments() {
+  public function testCreatePledgePaymentForMultipleInstallments(): void {
     $scheduled_date = date('Ymd', mktime(0, 0, 0, date("m"), date("d") + 2, date("y")));
     $contact_id = 2;
 
diff --git a/tests/phpunit/CRM/Price/BAO/PriceFieldTest.php b/tests/phpunit/CRM/Price/BAO/PriceFieldTest.php
index e6374edc7159..bd65b7e66d33 100644
--- a/tests/phpunit/CRM/Price/BAO/PriceFieldTest.php
+++ b/tests/phpunit/CRM/Price/BAO/PriceFieldTest.php
@@ -22,7 +22,7 @@ class CRM_Price_BAO_PriceFieldTest extends CiviUnitTestCase {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testSubmitPriceFieldWithOptions() {
+  public function testSubmitPriceFieldWithOptions(): void {
     $priceSet = $this->callAPISuccess('PriceSet', 'create', [
       'is_active' => 1,
       'extends' => 2,
@@ -80,7 +80,7 @@ public function testSubmitPriceFieldWithOptions() {
   /**
    * Test the name can be retrieved from the id using the pseudoConstant.
    */
-  public function testGetFromPseudoConstant() {
+  public function testGetFromPseudoConstant(): void {
     $this->assertNotEmpty(CRM_Core_PseudoConstant::getKey('CRM_Price_BAO_PriceField', 'price_set_id', 'default_contribution_amount'));
   }
 
diff --git a/tests/phpunit/CRM/Price/BAO/PriceFieldValueTest.php b/tests/phpunit/CRM/Price/BAO/PriceFieldValueTest.php
index 6dc246104333..1a1cf6d2697c 100644
--- a/tests/phpunit/CRM/Price/BAO/PriceFieldValueTest.php
+++ b/tests/phpunit/CRM/Price/BAO/PriceFieldValueTest.php
@@ -19,14 +19,14 @@ class CRM_Price_BAO_PriceFieldValueTest extends CiviUnitTestCase {
    * Verifies visibility field exists and is configured as a pseudoconstant
    * referencing the 'visibility' option group.
    */
-  public function testVisibilityFieldExists() {
+  public function testVisibilityFieldExists(): void {
     $fields = CRM_Price_DAO_PriceFieldValue::fields();
 
     $this->assertArrayKeyExists('visibility_id', $fields);
     $this->assertEquals('visibility', $fields['visibility_id']['pseudoconstant']['optionGroupName']);
   }
 
-  public function testEmptyStringLabel() {
+  public function testEmptyStringLabel(): void {
     // Put stuff here that should happen before all tests in this unit.
     $priceSetParams = [
       'name' => 'default_goat_priceset',
diff --git a/tests/phpunit/CRM/Price/Form/FieldTest.php b/tests/phpunit/CRM/Price/Form/FieldTest.php
index 0314289cbbd8..dc3b03778546 100644
--- a/tests/phpunit/CRM/Price/Form/FieldTest.php
+++ b/tests/phpunit/CRM/Price/Form/FieldTest.php
@@ -29,7 +29,7 @@ public function setUp(): void {
     ]);
   }
 
-  public function testPublicFieldWithOnlyAdminOptionsIsNotAllowed() {
+  public function testPublicFieldWithOnlyAdminOptionsIsNotAllowed(): void {
     $this->publicFieldParams['option_label'][1] = 'Admin Price';
     $this->publicFieldParams['option_amount'][1] = 10;
     $this->publicFieldParams['option_visibility_id'][1] = $this->visibilityOptionsKeys['admin'];
@@ -43,7 +43,7 @@ public function testPublicFieldWithOnlyAdminOptionsIsNotAllowed() {
     $this->assertTrue(array_key_exists('visibility_id', $validationResult));
   }
 
-  public function testAdminFieldDoesNotAllowPublicOptions() {
+  public function testAdminFieldDoesNotAllowPublicOptions(): void {
     $this->adminFieldParams['option_label'][1] = 'Admin Price';
     $this->adminFieldParams['option_amount'][1] = 10;
     $this->adminFieldParams['option_visibility_id'][1] = $this->visibilityOptionsKeys['public'];
@@ -119,7 +119,7 @@ private function initializeFieldParameters($params) {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testPriceFieldFormRuleOnMembership() {
+  public function testPriceFieldFormRuleOnMembership(): void {
     $membershipTypeID = $this->membershipTypeCreate();
     $membershipTypeID2 = $this->membershipTypeCreate(['member_of_contact_id' => $this->setupIDs['contact']]);
 
@@ -305,7 +305,7 @@ public function testPriceFieldFormRuleOnMembership() {
   /**
    * Test end date not allowed with only 'time' part.
    */
-  public function testEndDateWithoutDateNotAllowed() {
+  public function testEndDateWithoutDateNotAllowed(): void {
     $form = new CRM_Price_Form_Field();
     $form->_action = CRM_Core_Action::ADD;
     $values = $this->initializeFieldParameters([
@@ -318,7 +318,7 @@ public function testEndDateWithoutDateNotAllowed() {
   /**
    * Test end date must be after start date.
    */
-  public function testEndDateBeforeStartDateNotAllowed() {
+  public function testEndDateBeforeStartDateNotAllowed(): void {
     $form = new CRM_Price_Form_Field();
     $form->_action = CRM_Core_Action::ADD;
     $values = $this->initializeFieldParameters([
diff --git a/tests/phpunit/CRM/Queue/QueueTest.php b/tests/phpunit/CRM/Queue/QueueTest.php
index 89a3f4df69b3..0471fb731320 100644
--- a/tests/phpunit/CRM/Queue/QueueTest.php
+++ b/tests/phpunit/CRM/Queue/QueueTest.php
@@ -78,7 +78,7 @@ public function tearDown(): void {
    * If the queue has an automatic background runner (`runner`), then it
    * must also have an `error` policy.
    */
-  public function testRunnerRequiresErrorPolicy() {
+  public function testRunnerRequiresErrorPolicy(): void {
     try {
       $q1 = Civi::queue('test/incomplete/1', [
         'type' => 'Sql',
@@ -98,7 +98,7 @@ public function testRunnerRequiresErrorPolicy() {
     $this->assertTrue($q2 instanceof CRM_Queue_Queue_Sql);
   }
 
-  public function testStatuses() {
+  public function testStatuses(): void {
     $q1 = Civi::queue('test/valid/default', [
       'type' => 'Sql',
       'runner' => 'task',
@@ -119,7 +119,7 @@ public function testStatuses() {
     }
   }
 
-  public function testTemplating() {
+  public function testTemplating(): void {
     \Civi\Api4\Queue::create()->setValues([
       'is_template' => TRUE,
       'name' => 'test/template',
@@ -364,7 +364,7 @@ public function testPersistentUsage_api4($queueSpec) {
     }
   }
 
-  public function testFacadeAutoCreate() {
+  public function testFacadeAutoCreate(): void {
     $this->assertDBQuery(0, 'SELECT count(*) FROM civicrm_queue');
     $q1 = Civi::queue('testFacadeAutoCreate_q1', [
       'type' => 'Sql',
@@ -513,7 +513,7 @@ public function testBatchClaim($queueSpec) {
     $this->assertQueueStats(0, 0, 0, $this->queue);
   }
 
-  public function testSetStatus() {
+  public function testSetStatus(): void {
     $fired = ['status-changes' => []];
     \Civi::dispatcher()->addListener('hook_civicrm_queueStatus', function ($e) use (&$fired) {
       $fired[$e->queue->getName()][] = $e->status;
diff --git a/tests/phpunit/CRM/Queue/RunnerTest.php b/tests/phpunit/CRM/Queue/RunnerTest.php
index aa151910d856..c1456a0e75fd 100644
--- a/tests/phpunit/CRM/Queue/RunnerTest.php
+++ b/tests/phpunit/CRM/Queue/RunnerTest.php
@@ -93,7 +93,7 @@ public function testRunAllNormal(): void {
    *
    * One of the tasks will insert more TODOs at the start of the list.
    */
-  public function testRunAll_AddMore() {
+  public function testRunAll_AddMore(): void {
     // Prepare a list of tasks with an error in the middle.
     $this->queue->createItem(new CRM_Queue_Task(
       ['CRM_Queue_RunnerTest', '_recordValue'],
@@ -128,7 +128,7 @@ public function testRunAll_AddMore() {
    * Run a series of tasks; when one throws an
    * exception, ignore it and continue
    */
-  public function testRunAll_Continue_Exception() {
+  public function testRunAll_Continue_Exception(): void {
     // prepare a list of tasks with an error in the middle
     $this->queue->createItem(new CRM_Queue_Task(
       ['CRM_Queue_RunnerTest', '_recordValue'],
@@ -165,7 +165,7 @@ public function testRunAll_Continue_Exception() {
    * Run a series of tasks; when one throws an exception,
    * abort processing and return it to the queue.
    */
-  public function testRunAll_Abort_Exception() {
+  public function testRunAll_Abort_Exception(): void {
     // prepare a list of tasks with an error in the middle
     $this->queue->createItem(new CRM_Queue_Task(
       ['CRM_Queue_RunnerTest', '_recordValue'],
@@ -203,7 +203,7 @@ public function testRunAll_Abort_Exception() {
    * Run a series of tasks; when one returns false,
    * abort processing and return it to the queue.
    */
-  public function testRunAll_Abort_False() {
+  public function testRunAll_Abort_False(): void {
     // prepare a list of tasks with an error in the middle
     $this->queue->createItem(new CRM_Queue_Task(
       ['CRM_Queue_RunnerTest', '_recordValue'],
diff --git a/tests/phpunit/CRM/Report/Form/ActivityTest.php b/tests/phpunit/CRM/Report/Form/ActivityTest.php
index 688e05a2b7f4..c45eb370fab7 100644
--- a/tests/phpunit/CRM/Report/Form/ActivityTest.php
+++ b/tests/phpunit/CRM/Report/Form/ActivityTest.php
@@ -36,7 +36,7 @@ public function tearDown(): void {
   /**
    * Ensure long custom field names don't result in errors.
    */
-  public function testLongCustomFieldNames() {
+  public function testLongCustomFieldNames(): void {
     // Create custom group with long name and custom field with long name.
     $long_name = 'this is a very very very very long name with 65 characters in it';
     $group_params = [
@@ -67,7 +67,7 @@ public function testLongCustomFieldNames() {
   /**
    * Ensure that activity detail report only shows addres fields of target contact
    */
-  public function testTargetAddressFields() {
+  public function testTargetAddressFields(): void {
     $countryNames = array_flip(CRM_Core_PseudoConstant::country());
     // Create contact 1 and 2 with address fields, later considered as target contacts for activity
     $contactID1 = $this->individualCreate([
diff --git a/tests/phpunit/CRM/Report/Form/Contact/LoggingDetailTest.php b/tests/phpunit/CRM/Report/Form/Contact/LoggingDetailTest.php
index 67c717199427..b28e3dc01011 100644
--- a/tests/phpunit/CRM/Report/Form/Contact/LoggingDetailTest.php
+++ b/tests/phpunit/CRM/Report/Form/Contact/LoggingDetailTest.php
@@ -42,7 +42,7 @@ public function tearDown(): void {
   /**
    * Ensure a missing label name on a DAO won't crash the Logging Detail Report.
    */
-  public function testLabelFieldIsntRequired() {
+  public function testLabelFieldIsntRequired(): void {
     // Create an individual and a contribution in the same database connection (as if a new contact submitted a contribution online).
     $cid = $this->individualCreate();
     $this->contributionCreate(['contact_id' => $cid]);
diff --git a/tests/phpunit/CRM/Report/Form/Contribute/DetailTest.php b/tests/phpunit/CRM/Report/Form/Contribute/DetailTest.php
index fdb938fb143a..030efa23f9fd 100644
--- a/tests/phpunit/CRM/Report/Form/Contribute/DetailTest.php
+++ b/tests/phpunit/CRM/Report/Form/Contribute/DetailTest.php
@@ -264,7 +264,7 @@ public function testMultipleSoftCredits(): void {
   /**
    * Make sure the civicrm_alterReportVar hook for contribute detail report work well.
    */
-  public function testContributeDetailReportWithNewColumnFromCustomTable() {
+  public function testContributeDetailReportWithNewColumnFromCustomTable(): void {
     $this->quickCleanup($this->_tablesToTruncate);
 
     $solParams = [
diff --git a/tests/phpunit/CRM/Report/FormTest.php b/tests/phpunit/CRM/Report/FormTest.php
index a7712723d257..72d30be3fec3 100644
--- a/tests/phpunit/CRM/Report/FormTest.php
+++ b/tests/phpunit/CRM/Report/FormTest.php
@@ -64,7 +64,7 @@ private function fromToData() {
   /**
    * Test that getFromTo returns the correct dates.
    */
-  public function testGetFromTo() {
+  public function testGetFromTo(): void {
     $cases = $this->fromToData();
     foreach ($cases as $caseDescription => $case) {
       $obj = new CRM_Report_Form();
diff --git a/tests/phpunit/CRM/Report/Utils/ReportTest.php b/tests/phpunit/CRM/Report/Utils/ReportTest.php
index 42f09cc06d83..fa397d61653b 100644
--- a/tests/phpunit/CRM/Report/Utils/ReportTest.php
+++ b/tests/phpunit/CRM/Report/Utils/ReportTest.php
@@ -20,7 +20,7 @@ class CRM_Report_Utils_ReportTest extends CiviUnitTestCase {
   /**
    * Test makeCsv
    */
-  public function testMakeCsv() {
+  public function testMakeCsv(): void {
     $form = new CRM_Report_Form();
     $form->_columnHeaders = [
       'civicrm_activity_activity_type_id' => [
diff --git a/tests/phpunit/CRM/SMS/BAO/ProviderTest.php b/tests/phpunit/CRM/SMS/BAO/ProviderTest.php
index 699049b02e91..9e4a1d26624b 100644
--- a/tests/phpunit/CRM/SMS/BAO/ProviderTest.php
+++ b/tests/phpunit/CRM/SMS/BAO/ProviderTest.php
@@ -45,7 +45,7 @@ public function tearDown(): void {
   /**
    * CRM-19961 Check that when saving and updating a SMS provider with domain as NULL that it stays null
    */
-  public function testCreateAndUpdateProvider() {
+  public function testCreateAndUpdateProvider(): void {
     $values = [
       'domain_id' => NULL,
       'title' => 'test SMS provider',
@@ -72,7 +72,7 @@ public function testCreateAndUpdateProvider() {
    * @see https://issues.civicrm.org/jira/browse/CRM-20989
    * Add unit test to ensure that filtering by domain works in get Active Providers
    */
-  public function testActiveProviderCount() {
+  public function testActiveProviderCount(): void {
     $values = [
       'domain_id' => NULL,
       'title' => 'test SMS provider',
@@ -97,7 +97,7 @@ public function testActiveProviderCount() {
   /**
    * CRM-19961 Check that when a domain is not passed when saving it defaults to current domain when create
    */
-  public function testCreateWithoutDomain() {
+  public function testCreateWithoutDomain(): void {
     $values = [
       'title' => 'test SMS provider',
       'username' => 'test',
diff --git a/tests/phpunit/CRM/SMS/ProviderTest.php b/tests/phpunit/CRM/SMS/ProviderTest.php
index ba87f805ec23..fb1cef8ce844 100644
--- a/tests/phpunit/CRM/SMS/ProviderTest.php
+++ b/tests/phpunit/CRM/SMS/ProviderTest.php
@@ -47,7 +47,7 @@ public function tearDown(): void {
   /**
    * CRM-20238 Add test of the processInbound function for SMSs
    */
-  public function testProcessInbound() {
+  public function testProcessInbound(): void {
     $this->individualCreate(['phone' => [1 => ['phone_type_id' => 'Phone', 'location_type_id' => 'Home', 'phone' => '+61487654321']]]);
     $provider = new CiviTestSMSProvider('CiviTestSMSProvider');
     $result = $provider->processInbound('+61412345678', 'This is a test message', '+61487654321');
@@ -58,7 +58,7 @@ public function testProcessInbound() {
   /**
    * CRM-20238 Add test of processInbound function where no To is passed into the function
    */
-  public function testProcessInboundNoTo() {
+  public function testProcessInboundNoTo(): void {
     $provider = new CiviTestSMSProvider('CiviTestSMSProvider');
     $result = $provider->processInbound('+61412345678', 'This is a test message', NULL, '12345');
     $this->assertEquals('This is a test message', $result->details);
@@ -74,7 +74,7 @@ public function testProcessInboundNoTo() {
   /**
    * CRM-20238 Add test of ProcessInbound function where no To number is passed into the function but the toContactId gets set in a hook
    */
-  public function testProcessInboundSetToContactIDUsingHook() {
+  public function testProcessInboundSetToContactIDUsingHook(): void {
     $provider = new CiviTestSMSProvider('CiviTestSMSProvider');
     $this->hookClass->setHook('civicrm_inboundSMS', [$this, 'smsHookTest']);
     $result = $provider->processInbound('+61412345678', 'This is a test message', NULL, '12345');
@@ -96,7 +96,7 @@ public function smsHookTest(&$message) {
    * or the dummy SMS provider extension, might not provide a default url,
    * but the form shouldn't fail because of that.
    */
-  public function testMissingUrl() {
+  public function testMissingUrl(): void {
     $form = $this->getFormObject('CRM_SMS_Form_Provider');
     $_REQUEST['key'] = 'CiviTestSMSProvider';
 
diff --git a/tests/phpunit/CRM/UF/Page/ProfileEditorTest.php b/tests/phpunit/CRM/UF/Page/ProfileEditorTest.php
index 95814bce1909..4c5fc1e98fe6 100644
--- a/tests/phpunit/CRM/UF/Page/ProfileEditorTest.php
+++ b/tests/phpunit/CRM/UF/Page/ProfileEditorTest.php
@@ -9,7 +9,7 @@ class CRM_UF_Page_ProfileEditorTest extends CiviUnitTestCase {
   /**
    * Spot check a few fields that should appear in schema.
    */
-  public function testGetSchema() {
+  public function testGetSchema(): void {
     $schema = CRM_UF_Page_ProfileEditor::getSchema(['IndividualModel', 'ActivityModel']);
     foreach ($schema as $entityName => $entityDef) {
       foreach ($entityDef['schema'] as $fieldName => $fieldDef) {
@@ -45,7 +45,7 @@ public function testGetSchema() {
    * Test that with an extension adding in UF Fields for an enttiy that isn't supplied by Core e.g. Grant
    * That an appropriate entitytype can be specfied in the backbone.marionette profile editor e.g. GrantModel
    */
-  public function testGetSchemaWithHooks() {
+  public function testGetSchemaWithHooks(): void {
     CRM_Utils_Hook::singleton()->setHook('civicrm_alterUFFields', [$this, 'hook_civicrm_alterUFFIelds']);
     $schema = CRM_UF_Page_ProfileEditor::getSchema(['IndividualModel', 'GrantModel']);
     $this->assertEquals('Grant', $schema['GrantModel']['schema']['grant_id']['civiFieldType']);
@@ -54,7 +54,7 @@ public function testGetSchemaWithHooks() {
   /**
    * Tries to load up the profile schema for a model where there is no corresponding set of fields avaliable.
    */
-  public function testGetSchemaWithHooksWithInvalidModel() {
+  public function testGetSchemaWithHooksWithInvalidModel(): void {
     $this->expectException(CRM_Core_Exception::class);
     CRM_Utils_Hook::singleton()->setHook('civicrm_alterUFFields', [$this, 'hook_civicrm_alterUFFIelds']);
     $schema = CRM_UF_Page_ProfileEditor::getSchema(['IndividualModel', 'GrantModel', 'PledgeModel']);
diff --git a/tests/phpunit/CRM/Upgrade/FormTest.php b/tests/phpunit/CRM/Upgrade/FormTest.php
index d028bd82e237..9d8fe79709fc 100644
--- a/tests/phpunit/CRM/Upgrade/FormTest.php
+++ b/tests/phpunit/CRM/Upgrade/FormTest.php
@@ -10,7 +10,7 @@ class CRM_Upgrade_FormTest extends CiviUnitTestCase {
    * "php" requirement (composer.json) should match
    * CRM_Upgrade_Incremental_General::MIN_INSTALL_PHP_VER.
    */
-  public function testComposerRequirementMatch() {
+  public function testComposerRequirementMatch(): void {
     global $civicrm_root;
     $composerJsonPath = "{$civicrm_root}/composer.json";
     $this->assertFileExists($composerJsonPath);
diff --git a/tests/phpunit/CRM/Upgrade/Incremental/BaseTest.php b/tests/phpunit/CRM/Upgrade/Incremental/BaseTest.php
index 9aabcdc7afc7..bc4aee7771c9 100644
--- a/tests/phpunit/CRM/Upgrade/Incremental/BaseTest.php
+++ b/tests/phpunit/CRM/Upgrade/Incremental/BaseTest.php
@@ -97,7 +97,7 @@ public function testActionScheduleStringReplace(): void {
   /**
    * Test message upgrade process only edits the default if the template is customised.
    */
-  public function testMessageTemplateUpgradeAlreadyCustomised() {
+  public function testMessageTemplateUpgradeAlreadyCustomised(): void {
     $workFlowID = civicrm_api3('OptionValue', 'getvalue', ['return' => 'id', 'name' => 'membership_online_receipt', 'options' => ['limit' => 1, 'sort' => 'id DESC']]);
 
     $templates = $this->callAPISuccess('MessageTemplate', 'get', ['workflow_id' => $workFlowID])['values'];
@@ -132,7 +132,7 @@ public function testMessageTemplateUpgradeAlreadyCustomised() {
   /**
    * Test function for messages on upgrade.
    */
-  public function testMessageTemplateGetUpgradeMessages() {
+  public function testMessageTemplateGetUpgradeMessages(): void {
     \Civi\Api4\MessageTemplate::update(FALSE)
       ->addValue('msg_text', 'Edited text')
       ->addWhere('workflow_name', '=', 'contribution_online_receipt')
@@ -148,7 +148,7 @@ public function testMessageTemplateGetUpgradeMessages() {
   /**
    * Test converting a datepicker field.
    */
-  public function testSmartGroupDatePickerConversion() {
+  public function testSmartGroupDatePickerConversion(): void {
     $this->callAPISuccess('SavedSearch', 'create', [
       'form_values' => [
          ['grant_application_received_date_high', '=', '01/20/2019'],
@@ -181,7 +181,7 @@ public function testSmartGroupDatePickerConversion() {
   /**
    * Test Multiple Relative Date conversions
    */
-  public function testSmartGroupMultipleRelatvieDateConversions() {
+  public function testSmartGroupMultipleRelatvieDateConversions(): void {
     $this->callAPISuccess('SavedSearch', 'create', [
       'form_values' => [
         ['membership_join_date_low', '=', '20190903000000'],
@@ -220,7 +220,7 @@ public function testSmartGroupMultipleRelatvieDateConversions() {
   /**
    * Test upgrading multiple Event smart groups of different formats
    */
-  public function testMultipleEventSmartGroupDateConversions() {
+  public function testMultipleEventSmartGroupDateConversions(): void {
     $this->callAPISuccess('SavedSearch', 'create', [
       'form_values' => [
         ['event_start_date_low', '=', '20191001000000'],
@@ -285,7 +285,7 @@ public function testMultipleEventSmartGroupDateConversions() {
   /**
    * Test Log Date conversion
    */
-  public function testLogDateConversion() {
+  public function testLogDateConversion(): void {
     // Create two sets of searches one set for added by and one for modified by
     // Each set contains a relative search on this.month and a specific date search low
     $this->callAPISuccess('SavedSearch', 'create', [
@@ -380,7 +380,7 @@ public function testLogDateConversion() {
   /**
    * Test converting relationship fields
    */
-  public function testSmartGroupRelationshipDateConversions() {
+  public function testSmartGroupRelationshipDateConversions(): void {
     $this->callAPISuccess('SavedSearch', 'create', [
       'form_values' => [
         ['relationship_start_date_low', '=', '20191001000000'],
@@ -409,7 +409,7 @@ public function testSmartGroupRelationshipDateConversions() {
   /**
    * Test convert custom saved search
    */
-  public function testSmartGroupCustomDateRangeSearch() {
+  public function testSmartGroupCustomDateRangeSearch(): void {
     $this->createCustomGroupWithFieldOfType([], 'date');
     $dateCustomFieldName = $this->getCustomFieldName('date');
     $this->callAPISuccess('SavedSearch', 'create', [
@@ -464,7 +464,7 @@ public function testSmartGroupCustomDateRangeSearch() {
   /**
    * Test conversion of on hold group.
    */
-  public function testOnHoldConversion() {
+  public function testOnHoldConversion(): void {
     $this->callAPISuccess('SavedSearch', 'create', [
       'form_values' => [
         ['on_hold', '=', '1'],
@@ -481,7 +481,7 @@ public function testOnHoldConversion() {
   /**
    * Test renaming a field.
    */
-  public function testRenameField() {
+  public function testRenameField(): void {
     $this->callAPISuccess('SavedSearch', 'create', [
       'form_values' => [
         ['activity_date_low', '=', '01/22/2019'],
@@ -498,7 +498,7 @@ public function testRenameField() {
    *
    * @throws Exception
    */
-  public function testRenameFields() {
+  public function testRenameFields(): void {
     $this->callAPISuccess('SavedSearch', 'create', [
       'form_values' => [
         ['activity_date_low', '=', '01/22/2019'],
@@ -519,7 +519,7 @@ public function testRenameFields() {
    * Test that a mis-saved variable in 'contribute settings' can be converted to a
    * 'proper' setting.
    */
-  public function testConvertUpgradeContributeSettings() {
+  public function testConvertUpgradeContributeSettings(): void {
     $setting = [
       'deferred_revenue_enabled' => 1,
       'invoice_prefix' => 'G_',
@@ -546,7 +546,7 @@ public function testConvertUpgradeContributeSettings() {
   /**
    * dev/core#1405 Test fixing option groups with spaces in the name
    */
-  public function testFixOptionGroupName() {
+  public function testFixOptionGroupName(): void {
     $name = 'This is a test Name';
     $fixedName = CRM_Utils_String::titleToVar(strtolower($name));
     $optionGroup = $this->callAPISuccess('OptionGroup', 'create', [
@@ -570,7 +570,7 @@ public function testFixOptionGroupName() {
   /**
    * Test that if there is an option group name as the same as the proposed fix name that doesn't cause a hard fail in the upgrade
    */
-  public function testFixOptionGroupNameWithFixedNameInDatabase() {
+  public function testFixOptionGroupNameWithFixedNameInDatabase(): void {
     $name = 'This is a test Name';
     $fixedName = CRM_Utils_String::titleToVar(strtolower($name));
     $optionGroup = $this->callAPISuccess('OptionGroup', 'create', [
@@ -598,7 +598,7 @@ public function testFixOptionGroupNameWithFixedNameInDatabase() {
   /**
    * Test conversion between jcalendar and datepicker in reports
    */
-  public function testReportFormConvertDatePicker() {
+  public function testReportFormConvertDatePicker(): void {
     $report = $this->callAPISuccess('ReportInstance', 'create', [
       'report_id' => 'contribute/detail',
       'form_values' => [
@@ -732,7 +732,7 @@ public function testReportFormConvertDatePicker() {
     $this->assertEquals('1991-11-01 00:00:00', $formValues['receive_date_from']);
   }
 
-  public function testUpdateContactTypeNameField() {
+  public function testUpdateContactTypeNameField(): void {
     CRM_Core_DAO::executeQuery("INSERT INTO civicrm_contact_type (name,label,parent_id, is_active) VALUES ('', 'Test Contact Type', 1, 1)");
     CRM_Upgrade_Incremental_php_FiveTwentyEight::populateMissingContactTypeName();
     $contactType = $this->callAPISuccess('ContactType', 'getsingle', ['label' => 'Test Contact Type']);
@@ -740,7 +740,7 @@ public function testUpdateContactTypeNameField() {
     $this->callAPISuccess('ContactType', 'delete', ['id' => $contactType['id']]);
   }
 
-  public function testUpdateRelationshipCacheTable() {
+  public function testUpdateRelationshipCacheTable(): void {
     CRM_Core_DAO::executeQuery("ALTER TABLE civicrm_relationship_cache DEFAULT CHARACTER SET utf8 COLLATE utf8_unicode_ci");
     CRM_Upgrade_Incremental_php_FiveFortyThree::fixRelationshipCacheTableCollation();
     $contactTableCollation = CRM_Core_BAO_SchemaHandler::getInUseCollation();
diff --git a/tests/phpunit/CRM/Upgrade/Incremental/php/FiveFiftyFiveTest.php b/tests/phpunit/CRM/Upgrade/Incremental/php/FiveFiftyFiveTest.php
index c093289ddaa5..b00c288bad49 100644
--- a/tests/phpunit/CRM/Upgrade/Incremental/php/FiveFiftyFiveTest.php
+++ b/tests/phpunit/CRM/Upgrade/Incremental/php/FiveFiftyFiveTest.php
@@ -8,7 +8,7 @@
  */
 class CRM_Upgrade_Incremental_php_FiveFiftyFiveTest extends CiviCaseTestCase {
 
-  public function testFixingPrintLabelUpgrade() {
+  public function testFixingPrintLabelUpgrade(): void {
     CRM_Core_DAO::executeQuery("INSERT INTO civicrm_print_label (title, name, description, label_format_name, label_type_id, is_default, is_reserved, is_active, data) VALUES ('Annual Conference Hanging Badge (Avery 5395) Busted', 'Annual_Conference_Hanging_Badge_busted', 'For our annual conference', 'Avery 5395', 1, 1, 1, 1, '" . '{"title":"Annual Conference Hanging Badge (Avery 5395)","label_format_name":"Avery 5395","description":"For our annual conference","token":{"1":"{event.title}","2":"{contact.display_name}","3":"{contact.current_employer}","4":"{event.start_date|crmDate:\"%B %E%f\"}"},"font_name":{"1":"dejavusans","2":"dejavusans","3":"dejavusans","4":"dejavusans"},"font_size":{"1":"9","2":"20","3":"15","4":"9"},"font_style":{"1":"","2":"","3":"","4":""},"text_alignment":{"1":"L","2":"C","3":"C","4":"R"},"barcode_type":"barcode","barcode_alignment":"R","image_1":"","image_2":"","is_default":"1","is_active":"1","is_reserved":"1","_qf_default":"Layout:next","_qf_Layout_refresh":"Save and Preview"}' . "'),('Annual Conference Hanging Badge (Avery 5395) Fixed', 'Annual_Conference_Hanging_Badge_fixed', 'For our annual conference', 'Avery 5395', 1, 1, 1, 1, '" . '{"title":"Annual Conference Hanging Badge (Avery 5395)","label_format_name":"Avery 5395","description":"For our annual conference","token":{"1":"{event.title}","2":"{contact.display_name}","3":"{contact.current_employer}","4":"{event.start_date|crmDate:\\\"%B %E%f\\\"}"},"font_name":{"1":"dejavusans","2":"dejavusans","3":"dejavusans","4":"dejavusans"},"font_size":{"1":"9","2":"20","3":"15","4":"9"},"font_style":{"1":"","2":"","3":"","4":""},"text_alignment":{"1":"L","2":"C","3":"C","4":"R"},"barcode_type":"barcode","barcode_alignment":"R","image_1":"","image_2":"","is_default":"1","is_active":"1","is_reserved":"1","_qf_default":"Layout:next","_qf_Layout_refresh":"Save and Preview"}' . "')");
     $this->assertEquals(1, CRM_Core_DAO::singleValueQuery("SELECT count(id) FROM civicrm_print_label WHERE data like '%" . 'crmDate:\"%B %E%f\"' . "%'"));
     $originalFixed = CRM_Core_DAO::singleValueQuery("SELECT data FROM civicrm_print_label WHERE name = 'Annual_Conference_Hanging_Badge_fixed'");
diff --git a/tests/phpunit/CRM/Upgrade/Incremental/php/FiveSixtyFourTest.php b/tests/phpunit/CRM/Upgrade/Incremental/php/FiveSixtyFourTest.php
index 26b6a46cc917..25b0932ed84d 100644
--- a/tests/phpunit/CRM/Upgrade/Incremental/php/FiveSixtyFourTest.php
+++ b/tests/phpunit/CRM/Upgrade/Incremental/php/FiveSixtyFourTest.php
@@ -13,7 +13,7 @@ class CRM_Upgrade_Incremental_php_FiveSixtyFourTest extends CiviUnitTestCase {
   /**
    * Test that fixing the double json encode works as expected
    */
-  public function testFixDobuleJsonEncode() {
+  public function testFixDobuleJsonEncode(): void {
     $this->createAuthorizeNetProcessor();
     $this->paymentProcessorAuthorizeNetCreate();
     $creditCards = [
diff --git a/tests/phpunit/CRM/Upgrade/Incremental/php/FiveTwentyTest.php b/tests/phpunit/CRM/Upgrade/Incremental/php/FiveTwentyTest.php
index c0f9e7a69b17..fd84c645b475 100644
--- a/tests/phpunit/CRM/Upgrade/Incremental/php/FiveTwentyTest.php
+++ b/tests/phpunit/CRM/Upgrade/Incremental/php/FiveTwentyTest.php
@@ -11,7 +11,7 @@ class CRM_Upgrade_Incremental_php_FiveTwentyTest extends CiviCaseTestCase {
    * Test that the upgrade task changes the direction but only
    * for bidirectional relationship types that are b_a.
    */
-  public function testChangeCaseTypeAutoassignee() {
+  public function testChangeCaseTypeAutoassignee(): void {
 
     // We don't know what the ids are for the relationship types since it
     // seems to depend what ran before us, so retrieve them first and go by
@@ -191,7 +191,7 @@ public function testChangeCaseTypeAutoassignee() {
    * Test that the upgrade task converts case role <name>'s that
    * are labels to their name.
    */
-  public function testConvertRoleLabelsToNames() {
+  public function testConvertRoleLabelsToNames(): void {
 
     // We don't know what the ids are for the relationship types since it
     // seems to depend what ran before us, so retrieve them first and go by
diff --git a/tests/phpunit/CRM/Utils/API/MatchOptionTest.php b/tests/phpunit/CRM/Utils/API/MatchOptionTest.php
index c581d9b2e0b9..87ed486150cb 100644
--- a/tests/phpunit/CRM/Utils/API/MatchOptionTest.php
+++ b/tests/phpunit/CRM/Utils/API/MatchOptionTest.php
@@ -51,7 +51,7 @@ public function tearDown(): void {
   /**
    * If there's no pre-existing record, then insert a new one.
    */
-  public function testCreateMatch_none() {
+  public function testCreateMatch_none(): void {
     $result = $this->callAPISuccess('contact', 'create', [
       'options' => [
         'match' => ['first_name', 'last_name'],
@@ -69,7 +69,7 @@ public function testCreateMatch_none() {
   /**
    * If there's no pre-existing record, then throw an error.
    */
-  public function testCreateMatchMandatory_none() {
+  public function testCreateMatchMandatory_none(): void {
     $this->callAPIFailure('contact', 'create', [
       'options' => [
         'match-mandatory' => ['first_name', 'last_name'],
@@ -178,7 +178,7 @@ public function testCreateMatch_many($apiOptionName) {
    * When replacing one set with another set, match items within
    * the set using a key.
    */
-  public function testReplaceMatch_Email() {
+  public function testReplaceMatch_Email(): void {
     // Create contact with two emails (j1,j2)
     $createResult = $this->callAPISuccess('contact', 'create', [
       'contact_type' => 'Individual',
@@ -260,7 +260,7 @@ public function testReplaceMatch_Email() {
    * When replacing one set with another set, match items within
    * the set using a key.
    */
-  public function testReplaceMatch_Address() {
+  public function testReplaceMatch_Address(): void {
     // Create contact with two addresses (j1,j2)
     $createResult = $this->callAPISuccess('contact', 'create', [
       'contact_type' => 'Individual',
diff --git a/tests/phpunit/CRM/Utils/API/ReloadOptionTest.php b/tests/phpunit/CRM/Utils/API/ReloadOptionTest.php
index efd9298a28fa..46d09a484b9e 100644
--- a/tests/phpunit/CRM/Utils/API/ReloadOptionTest.php
+++ b/tests/phpunit/CRM/Utils/API/ReloadOptionTest.php
@@ -21,7 +21,7 @@ public function setUp(): void {
    * If reload option is missing, then 'create' returns the inputted nick_name -- despite the
    * fact that the hook manipulated the actual DB content.
    */
-  public function testNoReload() {
+  public function testNoReload(): void {
     $result = $this->callAPISuccess('contact', 'create', [
       'contact_type' => 'Individual',
       'first_name' => 'First',
@@ -36,7 +36,7 @@ public function testNoReload() {
   /**
    * When the reload option is unrecognized, generate an error
    */
-  public function testReloadInvalid() {
+  public function testReloadInvalid(): void {
     $this->callAPIFailure('contact', 'create', [
       'contact_type' => 'Individual',
       'first_name' => 'First',
@@ -52,7 +52,7 @@ public function testReloadInvalid() {
    * If reload option is set, then 'create' returns the final nick_name -- even if it
    * differs from the inputted nick_name.
    */
-  public function testReloadDefault() {
+  public function testReloadDefault(): void {
     $result = $this->callAPISuccess('contact', 'create', [
       'contact_type' => 'Individual',
       'first_name' => 'First',
@@ -70,7 +70,7 @@ public function testReloadDefault() {
    * When the reload option is combined with chaining, the reload should munge
    * the chain results.
    */
-  public function testReloadNoChainInterference() {
+  public function testReloadNoChainInterference(): void {
     $result = $this->callAPISuccess('contact', 'create', [
       'contact_type' => 'Individual',
       'first_name' => 'First',
@@ -92,7 +92,7 @@ public function testReloadNoChainInterference() {
    * When the reload option is combined with chaining, the reload should munge
    * the chain results, even if sequential=1.
    */
-  public function testReloadNoChainInterferenceSequential() {
+  public function testReloadNoChainInterferenceSequential(): void {
     $result = $this->callAPISuccess('contact', 'create', [
       'sequential' => 1,
       'contact_type' => 'Individual',
diff --git a/tests/phpunit/CRM/Utils/ArrayTest.php b/tests/phpunit/CRM/Utils/ArrayTest.php
index 19df34d5d346..5d2e152faa95 100644
--- a/tests/phpunit/CRM/Utils/ArrayTest.php
+++ b/tests/phpunit/CRM/Utils/ArrayTest.php
@@ -14,7 +14,7 @@ public function setUp(): void {
     $this->useTransaction();
   }
 
-  public function testAsColumns() {
+  public function testAsColumns(): void {
     $rowsNum = [
       ['a' => 10, 'b' => 11],
       ['a' => 20, 'b' => 21],
@@ -45,7 +45,7 @@ public function testAsColumns() {
     );
   }
 
-  public function testIndexArray() {
+  public function testIndexArray(): void {
     $inputs = [];
     $inputs[] = [
       'lang' => 'en',
@@ -88,7 +88,7 @@ public function testIndexArray() {
     $this->assertEquals($inputs[5], $byLangMsgid[NULL]['greeting']);
   }
 
-  public function testCollect() {
+  public function testCollect(): void {
     $arr = [
       ['catWord' => 'cat', 'dogWord' => 'dog'],
       ['catWord' => 'chat', 'dogWord' => 'chien'],
@@ -105,7 +105,7 @@ public function testCollect() {
     $this->assertEquals($expected, CRM_Utils_Array::collect('catWord', $arr));
   }
 
-  public function testProduct0() {
+  public function testProduct0(): void {
     $actual = CRM_Utils_Array::product(
       [],
       ['base data' => 1]
@@ -115,7 +115,7 @@ public function testProduct0() {
     ], $actual);
   }
 
-  public function testProduct1() {
+  public function testProduct1(): void {
     $actual = CRM_Utils_Array::product(
       ['dim1' => ['a', 'b']],
       ['base data' => 1]
@@ -126,7 +126,7 @@ public function testProduct1() {
     ], $actual);
   }
 
-  public function testProduct3() {
+  public function testProduct3(): void {
     $actual = CRM_Utils_Array::product(
       ['dim1' => ['a', 'b'], 'dim2' => ['alpha', 'beta'], 'dim3' => ['one', 'two']],
       ['base data' => 1]
@@ -143,7 +143,7 @@ public function testProduct3() {
     ], $actual);
   }
 
-  public function testIsSubset() {
+  public function testIsSubset(): void {
     $this->assertTrue(CRM_Utils_Array::isSubset([], []));
     $this->assertTrue(CRM_Utils_Array::isSubset(['a'], ['a']));
     $this->assertTrue(CRM_Utils_Array::isSubset(['a'], ['b', 'a', 'c']));
@@ -153,7 +153,7 @@ public function testIsSubset() {
     $this->assertFalse(CRM_Utils_Array::isSubset(['a'], ['b', 'c', 'd']));
   }
 
-  public function testRemove() {
+  public function testRemove(): void {
     $data = [
       'one' => 1,
       'two' => 2,
@@ -166,7 +166,7 @@ public function testRemove() {
     $this->assertEquals($data, ['six' => 6]);
   }
 
-  public function testGetSetPathParts() {
+  public function testGetSetPathParts(): void {
     $arr = $arrOrig = [
       'one' => '1',
       'two' => [
@@ -215,7 +215,7 @@ public function testGetSetPathParts() {
 
   }
 
-  public function testGetSet_EmptyPath() {
+  public function testGetSet_EmptyPath(): void {
     $emptyPath = [];
 
     $x = 'hello';
@@ -430,7 +430,7 @@ public function testBuildRecursiveValue($source, $path, $expected) {
   /**
    * Test the flatten function
    */
-  public function testFlatten() {
+  public function testFlatten(): void {
     $data = [
       'my_array' => [
         '0' => 'bar',
@@ -466,7 +466,7 @@ public function testFlatten() {
     $this->assertEquals($flat, $expected);
   }
 
-  public function testSingle() {
+  public function testSingle(): void {
     $okExamples = [
       ['abc'],
       [123],
diff --git a/tests/phpunit/CRM/Utils/AutoCleanTest.php b/tests/phpunit/CRM/Utils/AutoCleanTest.php
index 8c65827e5af2..746adb13863d 100644
--- a/tests/phpunit/CRM/Utils/AutoCleanTest.php
+++ b/tests/phpunit/CRM/Utils/AutoCleanTest.php
@@ -13,7 +13,7 @@ protected function setUp(): void {
     $this->useTransaction();
   }
 
-  public function testAutoclean() {
+  public function testAutoclean(): void {
     $this->foo = 'orig';
     $this->assertEquals('orig', $this->foo);
     $this->nestedWithArrayCb();
diff --git a/tests/phpunit/CRM/Utils/Cache/SqlGroupTest.php b/tests/phpunit/CRM/Utils/Cache/SqlGroupTest.php
index 2bfdcae2456e..5121282d6a67 100644
--- a/tests/phpunit/CRM/Utils/Cache/SqlGroupTest.php
+++ b/tests/phpunit/CRM/Utils/Cache/SqlGroupTest.php
@@ -9,7 +9,7 @@ class CRM_Utils_Cache_SqlGroupTest extends CiviUnitTestCase {
   /**
    * Add and remove two items from the same cache instance.
    */
-  public function testSameInstance() {
+  public function testSameInstance(): void {
     $a = new CRM_Utils_Cache_SqlGroup([
       'group' => 'testSameInstance',
     ]);
@@ -34,7 +34,7 @@ public function testSameInstance() {
   /**
    * Add item to one cache instance then read with another.
    */
-  public function testTwoInstance() {
+  public function testTwoInstance(): void {
     $a = new CRM_Utils_Cache_SqlGroup([
       'group' => 'testTwoInstance',
     ]);
@@ -54,7 +54,7 @@ public function testTwoInstance() {
   /**
    * Add item to one cache instance then read (with or without prefetch) from another
    */
-  public function testPrefetch() {
+  public function testPrefetch(): void {
     // 1. put data in cache
     $a = new CRM_Utils_Cache_SqlGroup([
       'group' => 'testPrefetch',
diff --git a/tests/phpunit/CRM/Utils/Check/Component/EnvTest.php b/tests/phpunit/CRM/Utils/Check/Component/EnvTest.php
index 67f4438f9c01..45efbd877672 100644
--- a/tests/phpunit/CRM/Utils/Check/Component/EnvTest.php
+++ b/tests/phpunit/CRM/Utils/Check/Component/EnvTest.php
@@ -17,7 +17,7 @@ public function setUp(): void {
    * File check test should fail if reached maximum timeout.
    * @throws \GuzzleHttp\Exception\GuzzleException
    */
-  public function testResourceUrlCheck() {
+  public function testResourceUrlCheck(): void {
     $check = new \CRM_Utils_Check_Component_Env();
     $failRequest = $check->fileExists('https://civicrm.org', 0.001);
     $successRequest = $check->fileExists('https://civicrm.org', 0);
diff --git a/tests/phpunit/CRM/Utils/Check/Component/OptionGroupsTest.php b/tests/phpunit/CRM/Utils/Check/Component/OptionGroupsTest.php
index 1b1a77f59f56..ad8f21baef70 100644
--- a/tests/phpunit/CRM/Utils/Check/Component/OptionGroupsTest.php
+++ b/tests/phpunit/CRM/Utils/Check/Component/OptionGroupsTest.php
@@ -13,7 +13,7 @@ public function setUp(): void {
     $this->useTransaction();
   }
 
-  public function testCheckOptionGroupValues() {
+  public function testCheckOptionGroupValues(): void {
     $optionGroup = $this->callAPISuccess('OptionGroup', 'create', [
       'name' => 'testGroup',
       'title' => 'testGroup',
diff --git a/tests/phpunit/CRM/Utils/DateTest.php b/tests/phpunit/CRM/Utils/DateTest.php
index c17368e4b814..65a21079785f 100644
--- a/tests/phpunit/CRM/Utils/DateTest.php
+++ b/tests/phpunit/CRM/Utils/DateTest.php
@@ -72,7 +72,7 @@ private function fromToData() {
   /**
    * Test that getFromTo returns the correct dates.
    */
-  public function testGetFromTo() {
+  public function testGetFromTo(): void {
     $cases = $this->fromToData();
     foreach ($cases as $caseDescription => $case) {
       $obj = new CRM_Utils_Date();
@@ -87,7 +87,7 @@ public function testGetFromTo() {
    *
    * Go backwards one year at a time through the sequence.
    */
-  public function testRelativeToAbsoluteFiscalYear() {
+  public function testRelativeToAbsoluteFiscalYear(): void {
     $sequence = ['this', 'previous', 'previous_before'];
     Civi::settings()->set('fiscalYearStart', ['M' => 7, 'd' => 1]);
     $fiscalYearStartYear = (strtotime('now') > strtotime((date('Y-07-01')))) ? date('Y') : (date('Y') - 1);
@@ -116,7 +116,7 @@ public function testRelativeToAbsoluteFiscalYear() {
    *
    * Go backwards one year at a time through the sequence.
    */
-  public function testRelativeToAbsoluteYear() {
+  public function testRelativeToAbsoluteYear(): void {
     $sequence = ['this', 'previous', 'previous_before'];
     $year = date('Y');
 
@@ -144,7 +144,7 @@ public function testRelativeToAbsoluteYear() {
    *
    * Go backwards one year at a time through the sequence.
    */
-  public function testRelativeEnding() {
+  public function testRelativeEnding(): void {
     $relativeDateValues = [
       'ending.week' => '- 6 days',
       'ending_30.day' => '- 29 days',
@@ -181,7 +181,7 @@ public function testRelativeEnding() {
    *
    * Go backwards one year at a time through the sequence.
    */
-  public function testRelativeThisFiscal() {
+  public function testRelativeThisFiscal(): void {
     $relativeDateValues = [
       'ending.week' => '- 6 days',
       'ending_30.day' => '- 29 days',
@@ -218,7 +218,7 @@ public function testRelativeThisFiscal() {
    *
    * Go backwards one year at a time through the sequence.
    */
-  public function testRelativeToAbsoluteYearRange() {
+  public function testRelativeToAbsoluteYearRange(): void {
     $sequence = ['previous_2'];
     $lastYear = (date('Y') - 1);
 
@@ -240,7 +240,7 @@ public function testRelativeToAbsoluteYearRange() {
    *
    * Go backwards one year at a time through the sequence.
    */
-  public function testRelativeToAbsoluteFiscalYearRange() {
+  public function testRelativeToAbsoluteFiscalYearRange(): void {
     $sequence = ['previous_2', 'previous_3', 'previous_4'];
     Civi::settings()->set('fiscalYearStart', ['M' => 7, 'd' => 1]);
     $lastFiscalYearEnd = (strtotime('now') > strtotime((date('Y-07-01')))) ? (date('Y')) : (date('Y') - 1);
@@ -2545,7 +2545,7 @@ public function relativeDateProvider(): array {
   /**
    * Test customFormat() function
    */
-  public function testCustomFormat() {
+  public function testCustomFormat(): void {
     $currentTimezone = date_default_timezone_get();
     date_default_timezone_set('America/Los_Angeles');
     $dateTime = "2018-11-08 21:46:44";
@@ -2574,7 +2574,7 @@ public function testCustomFormat() {
   /**
    * Test customFormat() function
    */
-  public function testCustomFormatTs() {
+  public function testCustomFormatTs(): void {
     $currentTimezone = date_default_timezone_get();
     date_default_timezone_set('America/Los_Angeles');
     $ts = mktime(21, 46, 44, 11, 8, 2018);
@@ -2602,7 +2602,7 @@ public function testCustomFormatTs() {
   /**
    * Verify that the Timezone works for daylight savings based on the passed in date
    */
-  public function testCustomFormatTimezoneDaylightSavings() {
+  public function testCustomFormatTimezoneDaylightSavings(): void {
     $currentTimezone = date_default_timezone_get();
     date_default_timezone_set('Australia/Sydney');
     $dateTime = '2018-11-08 21:46:44';
@@ -2613,7 +2613,7 @@ public function testCustomFormatTimezoneDaylightSavings() {
   /**
    * Test Earlier Day Relative term to absolute
    */
-  public function testRelativeEarlierDay() {
+  public function testRelativeEarlierDay(): void {
     $date = CRM_Utils_Date::relativeToAbsolute('earlier', 'day');
 
     $this->assertEquals([
@@ -2622,7 +2622,7 @@ public function testRelativeEarlierDay() {
     ], $date);
   }
 
-  public function testLocalizeConsts() {
+  public function testLocalizeConsts(): void {
     $expect['en_US'] = ['Jan', 'Tue', 'March', 'Thursday'];
     $expect['fr_FR'] = ['janv.', 'mar.', 'mars', 'jeudi'];
     $expect['es_MX'] = ['ene.', 'mar.', 'marzo', 'jueves'];
@@ -2640,7 +2640,7 @@ public function testLocalizeConsts() {
     }
   }
 
-  public function testWeekDayArrayOrder() {
+  public function testWeekDayArrayOrder(): void {
     $this->callAPISuccess('Setting', 'create', ['weekBegins' => 1]);
     $this->assertEquals([
       1 => 'Monday',
diff --git a/tests/phpunit/CRM/Utils/EnglishNumberTest.php b/tests/phpunit/CRM/Utils/EnglishNumberTest.php
index eba51d29c019..b19fde772e18 100644
--- a/tests/phpunit/CRM/Utils/EnglishNumberTest.php
+++ b/tests/phpunit/CRM/Utils/EnglishNumberTest.php
@@ -12,7 +12,7 @@ public function setUp(): void {
     $this->useTransaction();
   }
 
-  public function testRoundTrip() {
+  public function testRoundTrip(): void {
     for ($i = 0; $i < 100; $i++) {
       $camel = CRM_Utils_EnglishNumber::toCamelCase($i);
       $camelToInt = CRM_Utils_EnglishNumber::toInt($camel);
@@ -24,7 +24,7 @@ public function testRoundTrip() {
     }
   }
 
-  public function testCamel() {
+  public function testCamel(): void {
     $this->assertEquals('Seven', CRM_Utils_EnglishNumber::toCamelCase(7));
     $this->assertEquals('Nineteen', CRM_Utils_EnglishNumber::toCamelCase(19));
     $this->assertEquals('Thirty', CRM_Utils_EnglishNumber::toCamelCase(30));
@@ -32,7 +32,7 @@ public function testCamel() {
     $this->assertEquals('NinetyNine', CRM_Utils_EnglishNumber::toCamelCase(99));
   }
 
-  public function testHyphen() {
+  public function testHyphen(): void {
     $this->assertEquals('seven', CRM_Utils_EnglishNumber::toHyphen(7));
     $this->assertEquals('nineteen', CRM_Utils_EnglishNumber::toHyphen(19));
     $this->assertEquals('thirty', CRM_Utils_EnglishNumber::toHyphen(30));
@@ -40,7 +40,7 @@ public function testHyphen() {
     $this->assertEquals('ninety-nine', CRM_Utils_EnglishNumber::toHyphen(99));
   }
 
-  public function testIsNumeric() {
+  public function testIsNumeric(): void {
     $assertNumeric = function($expectBool, $string) {
       $this->assertEquals($expectBool, CRM_Utils_EnglishNumber::isNumeric($string), "isNumeric($string) should return " . (int) $expectBool);
     };
diff --git a/tests/phpunit/CRM/Utils/FileTest.php b/tests/phpunit/CRM/Utils/FileTest.php
index 333a49613d54..f514b70b0972 100644
--- a/tests/phpunit/CRM/Utils/FileTest.php
+++ b/tests/phpunit/CRM/Utils/FileTest.php
@@ -13,7 +13,7 @@ public function tearDown(): void {
   /**
    * Test is child path.
    */
-  public function testIsChildPath() {
+  public function testIsChildPath(): void {
     $testCases = [];
     $testCases[] = ['/ab/cd/ef', '/ab/cd', FALSE];
     $testCases[] = ['/ab/cd', '/ab/cd/ef', TRUE];
@@ -43,7 +43,7 @@ public function testIsChildPath() {
     }
   }
 
-  public function testStripComment() {
+  public function testStripComment(): void {
     $strings = [
       "\nab\n-- cd\nef" => "\nab\nef",
       "ab\n-- cd\nef" => "ab\nef",
@@ -152,7 +152,7 @@ public function testMimeTypeToExtension($mimeType, $expectedExtensions) {
   /**
    * Check a few variations of isIncludable
    */
-  public function testIsIncludable() {
+  public function testIsIncludable(): void {
     $path = \Civi::paths()->getPath('[civicrm.private]/');
     $bare_filename = 'afile' . time() . '.php';
     $file = "$path/$bare_filename";
@@ -213,7 +213,7 @@ public function testIsDirInvalidArgs($input, bool $expected) {
    * Just trying to include some of the same tests as php itself and
    * this doesn't fit in well to a dataprovider so is separate.
    */
-  public function testIsDirMkdir() {
+  public function testIsDirMkdir(): void {
     $a_dir = sys_get_temp_dir() . '/testIsDir';
     // I think temp is global to the test node, so if any test failed on this
     // in the past it doesn't get cleaned up and so already exists.
@@ -231,7 +231,7 @@ public function testIsDirMkdir() {
   /**
    * testIsDirSlashVariations
    */
-  public function testIsDirSlashVariations() {
+  public function testIsDirSlashVariations(): void {
     $a_dir = sys_get_temp_dir() . '/testIsDir';
     // I think temp is global to the test node, so if any test failed on this
     // in the past it doesn't get cleaned up and so already exists.
@@ -276,7 +276,7 @@ public function testIsDirSlashVariations() {
    * Test hard and soft links with isDir
    * Note hard links to directories aren't allowed so can only test with file.
    */
-  public function testIsDirLinks() {
+  public function testIsDirLinks(): void {
     if (strtoupper(substr(PHP_OS, 0, 3)) === 'WIN') {
       $this->markTestSkipped('Windows has links but not the same.');
     }
diff --git a/tests/phpunit/CRM/Utils/GlobalStackTest.php b/tests/phpunit/CRM/Utils/GlobalStackTest.php
index 1fa4c165ba42..9de48247a4bf 100644
--- a/tests/phpunit/CRM/Utils/GlobalStackTest.php
+++ b/tests/phpunit/CRM/Utils/GlobalStackTest.php
@@ -15,7 +15,7 @@ public function setUp(): void {
    * Temporarily override global variables and ensure that the variable data.
    * is set as expected (before/during/after the override).
    */
-  public function testPushPop() {
+  public function testPushPop(): void {
     global $_FOO, $_EXTRA;
 
     $_FOO['bar'] = 1;
diff --git a/tests/phpunit/CRM/Utils/HookTest.php b/tests/phpunit/CRM/Utils/HookTest.php
index 882db79ed2c6..fc3169fba50c 100644
--- a/tests/phpunit/CRM/Utils/HookTest.php
+++ b/tests/phpunit/CRM/Utils/HookTest.php
@@ -50,7 +50,7 @@ public function tearDown(): void {
   /**
    * Verify that runHooks() is reentrant by invoking one hook which calls another hooks
    */
-  public function testRunHooks_reentrancy() {
+  public function testRunHooks_reentrancy(): void {
     $arg1 = 'whatever';
     $null = NULL;
     $this->hook->runHooks($this->fakeModules, 'civicrm_testRunHooks_outer', 1, $arg1, $null, $null, $null, $null, $null);
@@ -70,7 +70,7 @@ public function testRunHooks_reentrancy() {
   /**
    * Verify that the results of runHooks() are correctly merged
    */
-  public function testRunHooks_merge() {
+  public function testRunHooks_merge(): void {
     $null = NULL;
     $result = $this->hook->runHooks($this->fakeModules, 'civicrm_testRunHooks_merge', 0, $null, $null, $null, $null, $null, $null);
     $this->assertEquals(
diff --git a/tests/phpunit/CRM/Utils/HttpClientTest.php b/tests/phpunit/CRM/Utils/HttpClientTest.php
index 225169c37916..715b53769f51 100644
--- a/tests/phpunit/CRM/Utils/HttpClientTest.php
+++ b/tests/phpunit/CRM/Utils/HttpClientTest.php
@@ -44,25 +44,25 @@ public function tearDown(): void {
     parent::tearDown();
   }
 
-  public function testFetchHttp() {
+  public function testFetchHttp(): void {
     $result = $this->client->fetch(self::VALID_HTTP_URL, $this->tmpFile);
     $this->assertEquals(CRM_Utils_HttpClient::STATUS_OK, $result);
     $this->assertMatchesRegularExpression(self::VALID_HTTP_REGEX, file_get_contents($this->tmpFile));
   }
 
-  public function testFetchHttps_valid() {
+  public function testFetchHttps_valid(): void {
     $result = $this->client->fetch(self::VALID_HTTPS_URL, $this->tmpFile);
     $this->assertEquals(CRM_Utils_HttpClient::STATUS_OK, $result);
     $this->assertMatchesRegularExpression(self::VALID_HTTPS_REGEX, file_get_contents($this->tmpFile));
   }
 
-  public function testFetchHttps_invalid_verify() {
+  public function testFetchHttps_invalid_verify(): void {
     $result = $this->client->fetch(self::SELF_SIGNED_HTTPS_URL, $this->tmpFile);
     $this->assertEquals(CRM_Utils_HttpClient::STATUS_DL_ERROR, $result);
     $this->assertEquals('', file_get_contents($this->tmpFile));
   }
 
-  public function testFetchHttps_invalid_noVerify() {
+  public function testFetchHttps_invalid_noVerify(): void {
     $result = civicrm_api('Setting', 'create', [
       'version' => 3,
       'verifySSL' => FALSE,
@@ -74,30 +74,30 @@ public function testFetchHttps_invalid_noVerify() {
     $this->assertMatchesRegularExpression(self::SELF_SIGNED_HTTPS_REGEX, file_get_contents($this->tmpFile));
   }
 
-  public function testFetchHttp_badOutFile() {
+  public function testFetchHttp_badOutFile(): void {
     $result = $this->client->fetch(self::VALID_HTTP_URL, '/ba/d/path/too/utput');
     $this->assertEquals(CRM_Utils_HttpClient::STATUS_WRITE_ERROR, $result);
   }
 
-  public function testGetHttp() {
+  public function testGetHttp(): void {
     [$status, $data] = $this->client->get(self::VALID_HTTP_URL);
     $this->assertEquals(CRM_Utils_HttpClient::STATUS_OK, $status);
     $this->assertMatchesRegularExpression(self::VALID_HTTP_REGEX, $data);
   }
 
-  public function testGetHttps_valid() {
+  public function testGetHttps_valid(): void {
     [$status, $data] = $this->client->get(self::VALID_HTTPS_URL);
     $this->assertEquals(CRM_Utils_HttpClient::STATUS_OK, $status);
     $this->assertMatchesRegularExpression(self::VALID_HTTPS_REGEX, $data);
   }
 
-  public function testGetHttps_invalid_verify() {
+  public function testGetHttps_invalid_verify(): void {
     [$status, $data] = $this->client->get(self::SELF_SIGNED_HTTPS_URL);
     $this->assertEquals(CRM_Utils_HttpClient::STATUS_DL_ERROR, $status);
     $this->assertEquals('', $data);
   }
 
-  public function testGetHttps_invalid_noVerify() {
+  public function testGetHttps_invalid_noVerify(): void {
     $result = civicrm_api('Setting', 'create', [
       'version' => 3,
       'verifySSL' => FALSE,
diff --git a/tests/phpunit/CRM/Utils/ICalendarTest.php b/tests/phpunit/CRM/Utils/ICalendarTest.php
index a4e7017aaf5a..8df08e898888 100644
--- a/tests/phpunit/CRM/Utils/ICalendarTest.php
+++ b/tests/phpunit/CRM/Utils/ICalendarTest.php
@@ -105,7 +105,7 @@ public function testSendParametersWithoutAttachment($parameters, $expected) {
   /**
    * Test Send with attachment.
    */
-  public function testSendWithAttachment() {
+  public function testSendWithAttachment(): void {
     $parameters = [
       'calendar_data', 'text/calendar', 'utf-8', 'civicrm_ical.ics', 'attachment',
     ];
diff --git a/tests/phpunit/CRM/Utils/LazyArrayTest.php b/tests/phpunit/CRM/Utils/LazyArrayTest.php
index e288f7cae8ca..43a051e017d1 100644
--- a/tests/phpunit/CRM/Utils/LazyArrayTest.php
+++ b/tests/phpunit/CRM/Utils/LazyArrayTest.php
@@ -11,7 +11,7 @@ public function setUp(): void {
     $this->useTransaction();
   }
 
-  public function testAssoc() {
+  public function testAssoc(): void {
     $l = $this->createFruitBasket();
     $this->assertFalse($l->isLoaded());
 
@@ -38,7 +38,7 @@ public function testAssoc() {
     $this->assertEquals(['a', 'b', 'c', 'd'], array_keys(CRM_Utils_Array::cast($l)));
   }
 
-  public function testNumeric() {
+  public function testNumeric(): void {
     $l = $this->createSeaRecords();
     $this->assertFalse($l->isLoaded());
 
@@ -65,7 +65,7 @@ public function testNumeric() {
     $this->assertEquals([0, 1, 2, 3], array_keys(CRM_Utils_Array::cast($l)));
   }
 
-  public function testBasicInspections() {
+  public function testBasicInspections(): void {
     $l = $this->createFruitBasket();
     $this->assertFalse($l->isLoaded());
 
@@ -80,7 +80,7 @@ public function testBasicInspections() {
     $this->assertTrue($l->isLoaded());
   }
 
-  public function testCopy() {
+  public function testCopy(): void {
     $l = $this->createFruitBasket();
     $copy = $l->getArrayCopy();
     $copy['d'] = 'date';
diff --git a/tests/phpunit/CRM/Utils/Mail/EmailProcessorInboundTest.php b/tests/phpunit/CRM/Utils/Mail/EmailProcessorInboundTest.php
index adafef7b5506..e05bd5b30a9b 100644
--- a/tests/phpunit/CRM/Utils/Mail/EmailProcessorInboundTest.php
+++ b/tests/phpunit/CRM/Utils/Mail/EmailProcessorInboundTest.php
@@ -62,7 +62,7 @@ public function tearDown(): void {
    * because it was also being used as a limit for backend processes. So we
    * test 4, which is bigger than 3 (unless running on a 2-bit CPU).
    */
-  public function testFetchActivitiesWithManyAttachments() {
+  public function testFetchActivitiesWithManyAttachments(): void {
     $mail = 'test_message_many_attachments.eml';
 
     // paranoid check that settings are the standard defaults
@@ -151,7 +151,7 @@ public function hookImplForEmailProcessor($type, &$params, $mail, &$result, $act
   /**
    * test hook_civicrm_emailProcessor
    */
-  public function testHookEmailProcessor() {
+  public function testHookEmailProcessor(): void {
     $this->hookClass->setHook('civicrm_emailProcessor', [$this, 'hookImplForEmailProcessor']);
 
     copy(__DIR__ . '/data/inbound/test_hook.eml', __DIR__ . '/data/mail/test_hook.eml');
@@ -220,7 +220,7 @@ public function hookImplForEmailProcessorContact($email, $contactID, &$result) {
   /**
    * test hook_civicrm_emailProcessorContact with catchall
    */
-  public function testHookEmailProcessorContactCatchall() {
+  public function testHookEmailProcessorContactCatchall(): void {
     $this->hookClass->setHook('civicrm_emailProcessorContact', [$this, 'hookImplForEmailProcessorContact']);
 
     // org with same domain as data fixture's email
@@ -239,7 +239,7 @@ public function testHookEmailProcessorContactCatchall() {
   /**
    * test hook_civicrm_emailProcessorContact with catchall but matching individual
    */
-  public function testHookEmailProcessorContactCatchallWithMatch() {
+  public function testHookEmailProcessorContactCatchallWithMatch(): void {
     $this->hookClass->setHook('civicrm_emailProcessorContact', [$this, 'hookImplForEmailProcessorContact']);
 
     // org with same domain as data fixture's email
@@ -265,7 +265,7 @@ public function testHookEmailProcessorContactCatchallWithMatch() {
    * here the presence of the matching individual is irrelevant - it will always
    * file on the org.
    */
-  public function testHookEmailProcessorContactAlwaysWithMatch() {
+  public function testHookEmailProcessorContactAlwaysWithMatch(): void {
     $this->hookClass->setHook('civicrm_emailProcessorContact', [$this, 'hookImplForEmailProcessorContact']);
 
     // org with same domain as data fixture's email
diff --git a/tests/phpunit/CRM/Utils/Mail/EmailProcessorTest.php b/tests/phpunit/CRM/Utils/Mail/EmailProcessorTest.php
index 506f12357881..f4b7272425ee 100644
--- a/tests/phpunit/CRM/Utils/Mail/EmailProcessorTest.php
+++ b/tests/phpunit/CRM/Utils/Mail/EmailProcessorTest.php
@@ -61,7 +61,7 @@ public function tearDown(): void {
   /**
    * Test the job processing function works and processes a bounce.
    */
-  public function testBounceProcessing() {
+  public function testBounceProcessing(): void {
     $this->setUpMailing();
 
     copy(__DIR__ . '/data/bounces/bounce_no_verp.txt', __DIR__ . '/data/mail/bounce_no_verp.txt');
@@ -74,7 +74,7 @@ public function testBounceProcessing() {
   /**
    * Test the job processing function can handle invalid characters.
    */
-  public function testBounceProcessingInvalidCharacter() {
+  public function testBounceProcessingInvalidCharacter(): void {
     $this->setUpMailing();
     $mail = 'test_invalid_character.eml';
 
@@ -87,7 +87,7 @@ public function testBounceProcessingInvalidCharacter() {
   /**
    * Test that the job processing function can handle incoming utf8mb4 characters.
    */
-  public function testBounceProcessingUTF8mb4() {
+  public function testBounceProcessingUTF8mb4(): void {
     $this->setUpMailing();
     $mail = 'test_utf8mb4_character.txt';
 
@@ -102,7 +102,7 @@ public function testBounceProcessingUTF8mb4() {
    *
    * Sample taken from https://www.phpclasses.org/browse/file/14672.html
    */
-  public function testProcessingMultipartRelatedEmail() {
+  public function testProcessingMultipartRelatedEmail(): void {
     $this->setUpMailing();
     $mail = 'test_sample_message.eml';
 
@@ -117,7 +117,7 @@ public function testProcessingMultipartRelatedEmail() {
    *
    * Sample anonymized from an email that broke bounce processing at Wikimedia
    */
-  public function testProcessingNestedMultipartEmail() {
+  public function testProcessingNestedMultipartEmail(): void {
     $this->setUpMailing();
     $mail = 'test_nested_message.eml';
 
@@ -142,7 +142,7 @@ public function testProcessingNestedMultipartEmail() {
    *
    * For not however, we are testing absence of mysql error in conjunction with CRM-20016.
    */
-  public function testBounceProcessingDeletedEmail() {
+  public function testBounceProcessingDeletedEmail(): void {
     $this->setUpMailing();
     $this->callAPISuccess('Email', 'get', [
       'contact_id' => $this->contactID,
@@ -206,7 +206,7 @@ public function setUpSkipNonCasesEmail() {
   /**
    * Test case email processing when is_non_case_email_skipped is enabled.
    */
-  public function testInboundProcessingCaseEmail() {
+  public function testInboundProcessingCaseEmail(): void {
     $this->setUpSkipNonCasesEmail();
     $mail = 'test_cases_email.eml';
 
@@ -222,7 +222,7 @@ public function testInboundProcessingCaseEmail() {
   /**
    * Test non case email processing when is_non_case_email_skipped is enabled.
    */
-  public function testInboundProcessingNonCaseEmail() {
+  public function testInboundProcessingNonCaseEmail(): void {
     $this->setUpSkipNonCasesEmail();
     $mail = 'test_non_cases_email.eml';
 
@@ -256,7 +256,7 @@ public function setUpDoNotCreateContact() {
   /**
    * Test case email processing when is_non_case_email_skipped is enabled.
    */
-  public function testInboundProcessingDoNotCreateContact() {
+  public function testInboundProcessingDoNotCreateContact(): void {
     $this->setUpDoNotCreateContact();
     $mail = 'test_non_cases_email.eml';
 
@@ -304,7 +304,7 @@ public function setUpNonDefaultActivityOptions() {
   /**
    * Test email processing with non-default activity options.
    */
-  public function testInboundProcessingNonDefaultActivityOptions() {
+  public function testInboundProcessingNonDefaultActivityOptions(): void {
     $params = $this->setUpNonDefaultActivityOptions();
     $mail = 'test_non_default_email.eml';
 
@@ -330,7 +330,7 @@ public function testInboundProcessingNonDefaultActivityOptions() {
   /**
    * Test not creating a contact for an email field that is not used.
    */
-  public function testInboundProcessingNoUnusedContacts() {
+  public function testInboundProcessingNoUnusedContacts(): void {
     $params = $this->setUpNonDefaultActivityOptions();
     $mail = 'test_non_default_email.eml';
 
diff --git a/tests/phpunit/CRM/Utils/Mail/FilteredPearMailerTest.php b/tests/phpunit/CRM/Utils/Mail/FilteredPearMailerTest.php
index 307db97b0ca9..3f916ac46dd8 100644
--- a/tests/phpunit/CRM/Utils/Mail/FilteredPearMailerTest.php
+++ b/tests/phpunit/CRM/Utils/Mail/FilteredPearMailerTest.php
@@ -11,7 +11,7 @@ public function setUp(): void {
     $this->useTransaction();
   }
 
-  public function testFilter() {
+  public function testFilter(): void {
     $mock = new class() extends \Mail {
       public $buf = [];
 
@@ -39,7 +39,7 @@ public function send($recipients, $headers, $body) {
     $this->assertEquals('all the fruits in the basket', $r);
   }
 
-  public function testFilter_shortCircuit() {
+  public function testFilter_shortCircuit(): void {
     $mock = new class() extends \Mail {
 
       public function send($recipients, $headers, $body) {
diff --git a/tests/phpunit/CRM/Utils/MoneyTest.php b/tests/phpunit/CRM/Utils/MoneyTest.php
index 11c6e133f91e..39757d1be981 100644
--- a/tests/phpunit/CRM/Utils/MoneyTest.php
+++ b/tests/phpunit/CRM/Utils/MoneyTest.php
@@ -23,7 +23,7 @@ public function testSubtractCurrencies($leftOp, $rightOp, $currency, $expectedRe
     $this->assertEquals($expectedResult, CRM_Utils_Money::subtractCurrencies($leftOp, $rightOp, $currency));
   }
 
-  public function testEquals() {
+  public function testEquals(): void {
     $testValue = 0.01;
 
     for ($i = 0; $i < 10; $i++) {
@@ -55,7 +55,7 @@ public function subtractCurrenciesDataProvider() {
    * In practice this only does rounding to 2 since rounding by any other amount is
    * only place-holder supported.
    */
-  public function testFormatLocaleNumericRoundedByCurrency() {
+  public function testFormatLocaleNumericRoundedByCurrency(): void {
     $result = CRM_Utils_Money::formatLocaleNumericRoundedByCurrency(8950.3678, 'NZD');
     $this->assertEquals('8,950.37', $result);
   }
@@ -67,7 +67,7 @@ public function testFormatLocaleNumericRoundedByCurrency() {
    * and , for decimal. (The Europeans are wrong but they don't know that. We will forgive them
    * because ... metric).
    */
-  public function testFormatLocaleNumericRoundedByCurrencyEuroThousand() {
+  public function testFormatLocaleNumericRoundedByCurrencyEuroThousand(): void {
     $this->setCurrencySeparators('.');
     $result = CRM_Utils_Money::formatLocaleNumericRoundedByCurrency(8950.3678, 'NZD');
     $this->assertEquals('8.950,37', $result);
@@ -109,7 +109,7 @@ public function testFormatLocaleNumericRoundedByOptionalPrecision($thousandSepar
   /**
    * Test that passing an invalid currency throws an error
    */
-  public function testInvalidCurrency() {
+  public function testInvalidCurrency(): void {
     $this->expectException(\CRM_Core_Exception::class, 'Invalid currency "NOT_A_CURRENCY"');
     CRM_Utils_Money::format(4.00, 'NOT_A_CURRENCY');
   }
diff --git a/tests/phpunit/CRM/Utils/PDF/UtilsTest.php b/tests/phpunit/CRM/Utils/PDF/UtilsTest.php
index ba81abe0f4aa..ca5cb8d53d42 100644
--- a/tests/phpunit/CRM/Utils/PDF/UtilsTest.php
+++ b/tests/phpunit/CRM/Utils/PDF/UtilsTest.php
@@ -14,7 +14,7 @@ public function setUp(): void {
   /**
    * Test user-supplied settings for DOMPDF
    */
-  public function testDOMPDFSettings() {
+  public function testDOMPDFSettings(): void {
     $old_setting = \Civi::settings()->get('dompdf_log_output_file');
 
     $log_file = tempnam(sys_get_temp_dir(), 'pdf');
diff --git a/tests/phpunit/CRM/Utils/RestTest.php b/tests/phpunit/CRM/Utils/RestTest.php
index 4fa1aa3148b8..8f4092bec07d 100644
--- a/tests/phpunit/CRM/Utils/RestTest.php
+++ b/tests/phpunit/CRM/Utils/RestTest.php
@@ -4,14 +4,14 @@
  * Class CRM_Utils_RestTest
  * @group headless
  */
-class CRM_Utils_RestTest extends CiviUnitTestCase  {
+class CRM_Utils_RestTest extends CiviUnitTestCase {
 
-  public function setUp() :void {
+  public function setUp(): void {
     parent::setUp();
     $this->useTransaction(TRUE);
   }
 
-  public function testProcessMultiple() {
+  public function testProcessMultiple(): void {
     $_SERVER['REQUEST_METHOD'] = 'POST';
     $input = [
       'cow' => [
@@ -40,7 +40,7 @@ public function testProcessMultiple() {
   /**
    * Check that check_permissions passed in in chained api calls is ignored.
    */
-  public function testSecurityIssue116() {
+  public function testSecurityIssue116(): void {
     $this->hookClass->setHook('civicrm_alterAPIPermissions', [$this, 'alterAPIPermissions']);
 
     $config = CRM_Core_Config::singleton();
@@ -55,7 +55,7 @@ public function testSecurityIssue116() {
       'name' => 'test',
       'domain_id' => 1,
     ])['id'];
-    $params = [ 'id' => $jobLogID, 'version' => 3, 'sequential' => 1, 'check_permissions' => 0 ];
+    $params = ['id' => $jobLogID, 'version' => 3, 'sequential' => 1, 'check_permissions' => 0];
     $args = ['civicrm', 'JobLog', 'get'];
 
     // Check we can load the email without checking perms.
@@ -96,7 +96,7 @@ public function testSecurityIssue116() {
     // Try create call AND using different api chain syntax.
     unset($params['api.contact.get']);
     $params['api_contact_create'] = [
-      ['contact_type' => 'Individual', 'display_name' => 'Sad Face', 'check_permissions' => 0]
+      ['contact_type' => 'Individual', 'display_name' => 'Sad Face', 'check_permissions' => 0],
     ];
     $output = CRM_Utils_REST::process($args, $params);
     $this->assertEquals(1, $output['is_error']);
@@ -111,7 +111,8 @@ public function testSecurityIssue116() {
         'id' => $contactID,
         'check_permissions' => 0,
         'return' => 'display_name',
-      ]];
+      ],
+    ];
     $output = CRM_Utils_REST::process($args, $params);
     $this->assertEquals($jobLogID, $output['id']);
     $chain = $output['values'][0]['api.job_log.get'];
@@ -128,4 +129,5 @@ public function alterAPIPermissions($entity, $action, &$params, &$permissions) {
       $permissions['job_log']['get'] = [];
     }
   }
+
 }
diff --git a/tests/phpunit/CRM/Utils/SQL/DeleteTest.php b/tests/phpunit/CRM/Utils/SQL/DeleteTest.php
index 7935f70a3f4c..aae64dad782a 100644
--- a/tests/phpunit/CRM/Utils/SQL/DeleteTest.php
+++ b/tests/phpunit/CRM/Utils/SQL/DeleteTest.php
@@ -11,26 +11,26 @@ public function setUp(): void {
     $this->useTransaction();
   }
 
-  public function testGetDefault() {
+  public function testGetDefault(): void {
     $del = CRM_Utils_SQL_Delete::from('foo');
     $this->assertLike('DELETE FROM foo', $del->toSQL());
   }
 
-  public function testWherePlain() {
+  public function testWherePlain(): void {
     $del = CRM_Utils_SQL_Delete::from('foo')
       ->where('foo = bar')
       ->where(['whiz = bang', 'frob > nicate']);
     $this->assertLike('DELETE FROM foo WHERE (foo = bar) AND (whiz = bang) AND (frob > nicate)', $del->toSQL());
   }
 
-  public function testWhereArg() {
+  public function testWhereArg(): void {
     $del = CRM_Utils_SQL_Delete::from('foo')
       ->where('foo = @value', ['@value' => 'not"valid'])
       ->where(['whiz > @base', 'frob != @base'], ['@base' => 'in"valid']);
     $this->assertLike('DELETE FROM foo WHERE (foo = "not\\"valid") AND (whiz > "in\\"valid") AND (frob != "in\\"valid")', $del->toSQL());
   }
 
-  public function testWhereNullArg() {
+  public function testWhereNullArg(): void {
     $del = CRM_Utils_SQL_Delete::from('foo')
       ->where('foo IS @value', ['@value' => NULL])
       ->where('nonexistent IS @nonexistent', [])
diff --git a/tests/phpunit/CRM/Utils/SQL/InsertTest.php b/tests/phpunit/CRM/Utils/SQL/InsertTest.php
index 1653585ebcab..ef5471be138d 100644
--- a/tests/phpunit/CRM/Utils/SQL/InsertTest.php
+++ b/tests/phpunit/CRM/Utils/SQL/InsertTest.php
@@ -11,7 +11,7 @@ public function setUp(): void {
     $this->useTransaction();
   }
 
-  public function testRow_twice() {
+  public function testRow_twice(): void {
     $insert = CRM_Utils_SQL_Insert::into('foo')
       ->row(['first' => '1', 'second' => '2'])
       ->row(['second' => '2b', 'first' => '1b']);
@@ -23,7 +23,7 @@ public function testRow_twice() {
     $this->assertLike($expected, $insert->toSQL());
   }
 
-  public function testRows() {
+  public function testRows(): void {
     $insert = CRM_Utils_SQL_Insert::into('foo')
       ->row(['first' => '1', 'second' => '2'])
       ->rows([
@@ -43,7 +43,7 @@ public function testRows() {
     $this->assertLike($expected, $insert->toSQL());
   }
 
-  public function testLiteral() {
+  public function testLiteral(): void {
     $insert = CRM_Utils_SQL_Insert::into('foo')
       ->allowLiterals()
       ->row(['first' => new CRM_Utils_SQL_Literal('1+1'), 'second' => '2'])
@@ -56,7 +56,7 @@ public function testLiteral() {
     $this->assertLike($expected, $insert->toSQL());
   }
 
-  public function testInsertIgnore() {
+  public function testInsertIgnore(): void {
     $insert = CRM_Utils_SQL_Insert::into('foo', 'INSERT IGNORE INTO')
       ->allowLiterals()
       ->row(['first' => new CRM_Utils_SQL_Literal('1+1'), 'second' => '2'])
diff --git a/tests/phpunit/CRM/Utils/SQL/SelectTest.php b/tests/phpunit/CRM/Utils/SQL/SelectTest.php
index 0e15bcf4846c..219e17414c9f 100644
--- a/tests/phpunit/CRM/Utils/SQL/SelectTest.php
+++ b/tests/phpunit/CRM/Utils/SQL/SelectTest.php
@@ -11,12 +11,12 @@ public function setUp(): void {
     $this->useTransaction();
   }
 
-  public function testGetDefault() {
+  public function testGetDefault(): void {
     $select = CRM_Utils_SQL_Select::from('foo bar');
     $this->assertLike('SELECT * FROM foo bar', $select->toSQL());
   }
 
-  public function testExecute_OK_fetch() {
+  public function testExecute_OK_fetch(): void {
     $select = CRM_Utils_SQL_Select::from('civicrm_contact')->select('count(*) as cnt');
     $this->assertLike('SELECT count(*) as cnt FROM civicrm_contact', $select->toSQL());
 
@@ -31,20 +31,20 @@ public function testExecute_OK_fetch() {
     $this->assertEquals(1, $rows);
   }
 
-  public function testExecute_OK_fetchValue() {
+  public function testExecute_OK_fetchValue(): void {
     $select = CRM_Utils_SQL_Select::from('civicrm_contact')->select('count(*) as cnt');
     $this->assertLike('SELECT count(*) as cnt FROM civicrm_contact', $select->toSQL());
     $this->assertTrue(is_numeric($select->execute()->fetchValue()));
   }
 
-  public function testExecute_OK_fetchAll() {
+  public function testExecute_OK_fetchAll(): void {
     $select = CRM_Utils_SQL_Select::from('civicrm_contact')->select('count(*) as cnt');
     $this->assertLike('SELECT count(*) as cnt FROM civicrm_contact', $select->toSQL());
     $records = $select->execute()->fetchAll();
     $this->assertTrue(is_numeric($records[0]['cnt']));
   }
 
-  public function testExecute_Error() {
+  public function testExecute_Error(): void {
     $select = CRM_Utils_SQL_Select::from('civicrm_contact')->select('snarb;barg');
 
     try {
@@ -56,28 +56,28 @@ public function testExecute_Error() {
     }
   }
 
-  public function testGetFields() {
+  public function testGetFields(): void {
     $select = CRM_Utils_SQL_Select::from('foo')
       ->select('bar')
       ->select(['whiz', 'bang']);
     $this->assertLike('SELECT bar, whiz, bang FROM foo', $select->toSQL());
   }
 
-  public function testWherePlain() {
+  public function testWherePlain(): void {
     $select = CRM_Utils_SQL_Select::from('foo')
       ->where('foo = bar')
       ->where(['whiz = bang', 'frob > nicate']);
     $this->assertLike('SELECT * FROM foo WHERE (foo = bar) AND (whiz = bang) AND (frob > nicate)', $select->toSQL());
   }
 
-  public function testWhereArg() {
+  public function testWhereArg(): void {
     $select = CRM_Utils_SQL_Select::from('foo')
       ->where('foo = @value', ['@value' => 'not"valid'])
       ->where(['whiz > @base', 'frob != @base'], ['@base' => 'in"valid']);
     $this->assertLike('SELECT * FROM foo WHERE (foo = "not\\"valid") AND (whiz > "in\\"valid") AND (frob != "in\\"valid")', $select->toSQL());
   }
 
-  public function testWhereNullArg() {
+  public function testWhereNullArg(): void {
     $select = CRM_Utils_SQL_Select::from('foo')
       ->where('foo IS @value', ['@value' => NULL])
       ->where('nonexistent IS @nonexistent', [])
@@ -86,14 +86,14 @@ public function testWhereNullArg() {
     $this->assertLike('SELECT * FROM foo WHERE (foo IS NULL) AND (nonexistent IS @nonexistent) AND (morenonexistent IS @nonexistent) AND (bar IS "null")', $select->toSQL());
   }
 
-  public function testGroupByPlain() {
+  public function testGroupByPlain(): void {
     $select = CRM_Utils_SQL_Select::from('foo')
       ->groupBy("bar_id")
       ->groupBy(['whiz_id*2', 'lower(bang)']);
     $this->assertLike('SELECT * FROM foo GROUP BY bar_id, whiz_id*2, lower(bang)', $select->toSQL());
   }
 
-  public function testHavingPlain() {
+  public function testHavingPlain(): void {
     $select = CRM_Utils_SQL_Select::from('foo')
       ->groupBy("bar_id")
       ->having('count(id) > 2')
@@ -101,7 +101,7 @@ public function testHavingPlain() {
     $this->assertLike('SELECT * FROM foo GROUP BY bar_id HAVING (count(id) > 2) AND (sum(id) > 10) AND (avg(id) < 200)', $select->toSQL());
   }
 
-  public function testHavingArg() {
+  public function testHavingArg(): void {
     $select = CRM_Utils_SQL_Select::from('foo')
       ->groupBy("bar_id")
       ->having('count(id) > #mincnt', ['#mincnt' => 2])
@@ -109,33 +109,33 @@ public function testHavingArg() {
     $this->assertLike('SELECT * FROM foo GROUP BY bar_id HAVING (count(id) > 2) AND (sum(id) > 10) AND (avg(id) < 10)', $select->toSQL());
   }
 
-  public function testOrderByPlain() {
+  public function testOrderByPlain(): void {
     $select = CRM_Utils_SQL_Select::from('foo bar')
       ->orderBy('first asc')
       ->orderBy(['second desc', 'third']);
     $this->assertLike('SELECT * FROM foo bar ORDER BY first asc, second desc, third', $select->toSQL());
   }
 
-  public function testLimit_defaultOffset() {
+  public function testLimit_defaultOffset(): void {
     $select = CRM_Utils_SQL_Select::from('foo bar')
       ->limit(20);
     $this->assertLike('SELECT * FROM foo bar LIMIT 20 OFFSET 0', $select->toSQL());
   }
 
-  public function testLimit_withOffset() {
+  public function testLimit_withOffset(): void {
     $select = CRM_Utils_SQL_Select::from('foo bar')
       ->limit(20, 60);
     $this->assertLike('SELECT * FROM foo bar LIMIT 20 OFFSET 60', $select->toSQL());
   }
 
-  public function testLimit_disable() {
+  public function testLimit_disable(): void {
     $select = CRM_Utils_SQL_Select::from('foo bar')
       ->limit(20, 60)
       ->limit(NULL, NULL);
     $this->assertLike('SELECT * FROM foo bar', $select->toSQL());
   }
 
-  public function testModeOutput() {
+  public function testModeOutput(): void {
     $select = CRM_Utils_SQL_Select::from('foo', ['mode' => 'out'])
       ->where('foo = @value')
       ->where([
@@ -170,7 +170,7 @@ public function testModeOutput() {
     }
   }
 
-  public function testBig() {
+  public function testBig(): void {
     $select = CRM_Utils_SQL_Select::from('foo')
       ->select('foo.id')
       ->join('rel1', 'INNER JOIN rel1_table rel1 ON foo.id = rel1.foo_id')
@@ -197,7 +197,7 @@ public function testBig() {
    * Parameter-values could include control characters like
    * '"@" or "!", but they should never be evaluated.
    */
-  public function testNoIterativeInterpolation() {
+  public function testNoIterativeInterpolation(): void {
     $select = CRM_Utils_SQL_Select::from('foo')
       ->where('a = @a and b = @b and c = @c', [
         'a' => '@b',
@@ -207,7 +207,7 @@ public function testNoIterativeInterpolation() {
     $this->assertLike('SELECT * FROM foo WHERE (a = "@b" and b = "@c" and c = "@a")', $select->toSQL());
   }
 
-  public function testInterpolate() {
+  public function testInterpolate(): void {
     $actual = CRM_Utils_SQL_Select::from('ignore')->interpolate(
       '@escaped !unescaped #validated',
       [
@@ -219,7 +219,7 @@ public function testInterpolate() {
     $this->assertLike('"foo\"bar" concat(foo,bar) 15.2', $actual);
   }
 
-  public function testInterpolateWildcard() {
+  public function testInterpolateWildcard(): void {
     $actual = CRM_Utils_SQL_Select::from('ignore')->interpolate(
       'escaped @escaped unescaped !unescaped validated #validated',
       [
@@ -231,7 +231,7 @@ public function testInterpolateWildcard() {
     $this->assertLike('escaped "foo\"bar" unescaped concat(foo,bar) validated 15.2', $actual);
   }
 
-  public function testInterpolateUnknown() {
+  public function testInterpolateUnknown(): void {
     $actual = CRM_Utils_SQL_Select::from('ignore')->interpolate(
       'escaped @escaped unescaped !unescaped validated #validated',
       [
@@ -241,7 +241,7 @@ public function testInterpolateUnknown() {
     $this->assertLike('escaped @escaped unescaped !unescaped validated #validated', $actual);
   }
 
-  public function testInterpolateUnknownStrict() {
+  public function testInterpolateUnknownStrict(): void {
     try {
       CRM_Utils_SQL_Select::from('ignore')
         ->strict()
@@ -257,7 +257,7 @@ public function testInterpolateUnknownStrict() {
     }
   }
 
-  public function testInterpolateArray() {
+  public function testInterpolateArray(): void {
     $actual = CRM_Utils_SQL_Select::from('ignore')->interpolate(
       '(@escaped) (!unescaped) (#validated)',
       [
@@ -269,7 +269,7 @@ public function testInterpolateArray() {
     $this->assertLike('("foo\\"bar", "whiz", "null", NULL, "bang") (foo"bar, bar) (1, 10, NULL, 100.1)', $actual);
   }
 
-  public function testInterpolateBadNumber() {
+  public function testInterpolateBadNumber(): void {
     try {
       $result = CRM_Utils_SQL_Select::from('ignore')->interpolate('#num', [
         '#num' => '5not-a-number5',
@@ -291,7 +291,7 @@ public function testInterpolateBadNumber() {
     }
   }
 
-  public function testMerge() {
+  public function testMerge(): void {
     $fragmentOutMode = CRM_Utils_SQL_Select::fragment()
       ->select(['a', 'b'])
       ->where('a = #two')
@@ -308,7 +308,7 @@ public function testMerge() {
     $this->assertLike('SELECT c, d, a, b, e FROM foo WHERE (c = "4") AND (a = 2) AND (whipit())', $query->toSQL());
   }
 
-  public function testUnion() {
+  public function testUnion(): void {
     $a = CRM_Utils_SQL_Select::from('a')->select('a_name')->where('a1 = !num')->param('num', 100);
     $b = CRM_Utils_SQL_Select::from('b')->select('b_name')->where('b2 = @val')->param('val', "ab cd");
     $u = CRM_Utils_SQL_Select::fromSet()->union('ALL', [$a, $b])->limit(100)->orderBy('a_name');
@@ -318,7 +318,7 @@ public function testUnion() {
     $this->assertLike($expectUnion, $u->toSQL());
   }
 
-  public function testUnionIntersect() {
+  public function testUnionIntersect(): void {
     $a = CRM_Utils_SQL_Select::from('a')->select('a_name')->where('a1 = !num')->param('num', 100);
     $b = CRM_Utils_SQL_Select::from('b')->select('b_name')->where('b2 = @val')->param('val', "bb bb");
     $c = CRM_Utils_SQL_Select::from('c')->select('c_name')->where('c3 = @val')->param('val', "cc cc");
@@ -334,13 +334,13 @@ public function testUnionIntersect() {
     $this->assertLike($expectUnion, $u->toSQL());
   }
 
-  public function testArrayGet() {
+  public function testArrayGet(): void {
     $select = CRM_Utils_SQL_Select::from("foo")
       ->param('hello', 'world');
     $this->assertEquals('world', $select['hello']);
   }
 
-  public function testInsertInto_WithDupes() {
+  public function testInsertInto_WithDupes(): void {
     $select = CRM_Utils_SQL_Select::from('foo')
       ->insertInto('bar', ['first', 'second', 'third', 'fourth'])
       ->select('fid')
@@ -356,7 +356,7 @@ public function testInsertInto_WithDupes() {
     $this->assertLike('INSERT INTO bar (first, second, third, fourth) SELECT fid, 1, fid, 1 FROM foo WHERE (zoo = 3) AND (aviary = 3) GROUP BY noodle, sauce', $select->toSQL());
   }
 
-  public function testInsertInto_OnDuplicateUpdate() {
+  public function testInsertInto_OnDuplicateUpdate(): void {
     $select = CRM_Utils_SQL_Select::from('foo')
       ->insertInto('bar', ['first', 'second', 'third'])
       ->select(['foo.one', 'foo.two', 'foo.three'])
@@ -365,7 +365,7 @@ public function testInsertInto_OnDuplicateUpdate() {
     $this->assertLike('INSERT INTO bar (first, second, third) SELECT foo.one, foo.two, foo.three FROM foo ON DUPLICATE KEY UPDATE second = twiddle(foo.two), third = twiddle(foo.three)', $select->toSQL());
   }
 
-  public function testSyncInto_EarlyInterpolate() {
+  public function testSyncInto_EarlyInterpolate(): void {
     $select = CRM_Utils_SQL_Select::from('foo')
       ->where('foo.whiz = 100')
       ->syncInto('bar', ['name'], [
@@ -378,7 +378,7 @@ public function testSyncInto_EarlyInterpolate() {
     $this->assertLike('INSERT INTO bar (name, first, second) SELECT foo.name, concat(foo.one, " and more"), foo.two FROM foo WHERE (foo.whiz = 100) ON DUPLICATE KEY UPDATE first = concat(foo.one, " and more"), second = foo.two', $select->toSQL());
   }
 
-  public function testSyncInto_LateInterpolate() {
+  public function testSyncInto_LateInterpolate(): void {
     $select = CRM_Utils_SQL_Select::from('foo')
       ->where('foo.whiz = 100')
       ->syncInto('bar', ['name'], [
diff --git a/tests/phpunit/CRM/Utils/SQLTest.php b/tests/phpunit/CRM/Utils/SQLTest.php
index e4c4bbe25cf9..80d336fce7e2 100644
--- a/tests/phpunit/CRM/Utils/SQLTest.php
+++ b/tests/phpunit/CRM/Utils/SQLTest.php
@@ -11,7 +11,7 @@ public function setUp(): void {
     $this->useTransaction();
   }
 
-  public function testInterpolate() {
+  public function testInterpolate(): void {
     // This function is a thin wrapper for `CRM_Utils_SQL_BaseParamQuery::interpolate()`, which already has
     // lots of coverage in other test classes. This test just checks the basic wiring.
     $sql = CRM_Utils_SQL::interpolate('FROBNICATE some_table WITH MAX(!dynamicField) OVER #times USING (@list) OR (#ids) OR @item', [
@@ -24,7 +24,7 @@ public function testInterpolate() {
     $this->assertEquals('FROBNICATE some_table WITH MAX(the(field)) OVER 123 USING ("abc def", "45") OR (6, 7, 8) OR "it\\\'s text"', $sql);
   }
 
-  public function testInterpolateBad() {
+  public function testInterpolateBad(): void {
     try {
       CRM_Utils_SQL::interpolate("UPDATE !the_table SET !the_field = @THE_VALUE", [
         // MISSING: 'the_table'
diff --git a/tests/phpunit/CRM/Utils/SignerTest.php b/tests/phpunit/CRM/Utils/SignerTest.php
index aef18d5684b3..901cad4182ba 100644
--- a/tests/phpunit/CRM/Utils/SignerTest.php
+++ b/tests/phpunit/CRM/Utils/SignerTest.php
@@ -20,7 +20,7 @@ public function setUp(): void {
     $this->useTransaction();
   }
 
-  public function testSignValidate() {
+  public function testSignValidate(): void {
     $cases = [];
     $cases[] = [
       'signParams' => [
diff --git a/tests/phpunit/CRM/Utils/SystemTest.php b/tests/phpunit/CRM/Utils/SystemTest.php
index 964231da53b8..6334b36732a8 100644
--- a/tests/phpunit/CRM/Utils/SystemTest.php
+++ b/tests/phpunit/CRM/Utils/SystemTest.php
@@ -12,7 +12,7 @@ public function setUp(): void {
     $this->useTransaction();
   }
 
-  public function testUrlQueryString() {
+  public function testUrlQueryString(): void {
     $config = CRM_Core_Config::singleton();
     $this->assertTrue($config->userSystem instanceof CRM_Utils_System_UnitTests);
     $expected = '/index.php?q=civicrm/foo/bar&foo=ab&bar=cd%26ef';
@@ -20,7 +20,7 @@ public function testUrlQueryString() {
     $this->assertEquals($expected, $actual);
   }
 
-  public function testUrlQueryArray() {
+  public function testUrlQueryArray(): void {
     $config = CRM_Core_Config::singleton();
     $this->assertTrue($config->userSystem instanceof CRM_Utils_System_UnitTests);
     $expected = '/index.php?q=civicrm/foo/bar&foo=ab&bar=cd%26ef';
@@ -31,7 +31,7 @@ public function testUrlQueryArray() {
     $this->assertEquals($expected, $actual);
   }
 
-  public function testEvalUrl() {
+  public function testEvalUrl(): void {
     $this->assertEquals(FALSE, CRM_Utils_System::evalUrl(FALSE));
     $this->assertEquals('http://example.com/', CRM_Utils_System::evalUrl('http://example.com/'));
     $this->assertEquals('http://example.com/?cms=UnitTests', CRM_Utils_System::evalUrl('http://example.com/?cms={uf}'));
@@ -118,7 +118,7 @@ public function getURLs() {
   /**
    * Test extern url.
    */
-  public function testExternUrl() {
+  public function testExternUrl(): void {
     $siteKey = mt_rand();
     $apiKey = mt_rand();
     $restUrl = CRM_Utils_System::externUrl('extern/rest', "entity=Contact&action=get&key=$siteKey&api_key=$apiKey");
@@ -190,7 +190,7 @@ public function getExternURLs() {
   /**
    * Demonstrate the, um, "flexibility" of isNull
    */
-  public function testIsNull() {
+  public function testIsNull(): void {
     $this->assertTrue(CRM_Utils_System::isNull(NULL));
     $this->assertTrue(CRM_Utils_System::isNull(''));
     $this->assertTrue(CRM_Utils_System::isNull('null'));
@@ -283,7 +283,7 @@ public function testCrudLink($params, $expectedResult) {
   /**
    * Test that flushing cache clears the asset cache.
    */
-  public function testFlushCacheClearsAssetCache() {
+  public function testFlushCacheClearsAssetCache(): void {
     // We need to get the file path for the folder and there isn't a public
     // method to get it, so create a file in the folder using public methods,
     // then get the path from that, then flush the cache, then check if the
diff --git a/tests/phpunit/CRM/Utils/TokenConsistencyTest.php b/tests/phpunit/CRM/Utils/TokenConsistencyTest.php
index 16f5c5eecc70..d33bb0a979fe 100644
--- a/tests/phpunit/CRM/Utils/TokenConsistencyTest.php
+++ b/tests/phpunit/CRM/Utils/TokenConsistencyTest.php
@@ -1069,7 +1069,7 @@ protected function createEventAndParticipant(): void {
     ]);
   }
 
-  public function testEscaping() {
+  public function testEscaping(): void {
     $autoClean = [];
     $create = function(string $entity, array $record = []) use (&$autoClean) {
       // It's convenient to use createTestObject(), but it doesn't reproduce the normal escaping rules from QuickForm/APIv3/APIv4.
diff --git a/tests/phpunit/CRM/Utils/TypeTest.php b/tests/phpunit/CRM/Utils/TypeTest.php
index 0b536df98241..ac47a540bf52 100644
--- a/tests/phpunit/CRM/Utils/TypeTest.php
+++ b/tests/phpunit/CRM/Utils/TypeTest.php
@@ -208,7 +208,7 @@ public function getPhpTypeExamples() {
     return $es;
   }
 
-  public function testValidatePhpType() {
+  public function testValidatePhpType(): void {
 
     // This test runs much faster as one test-func rather than data-provider func.
     foreach ($this->getPhpTypeExamples() as $exampleId => $example) {
diff --git a/tests/phpunit/CRM/Utils/ZipTest.php b/tests/phpunit/CRM/Utils/ZipTest.php
index 5b43c3f473fa..7afc9bff1a94 100644
--- a/tests/phpunit/CRM/Utils/ZipTest.php
+++ b/tests/phpunit/CRM/Utils/ZipTest.php
@@ -34,63 +34,63 @@ public function tearDown(): void {
     }
   }
 
-  public function testFindBaseDirName_normal() {
+  public function testFindBaseDirName_normal(): void {
     $this->_doFindBaseDirName('author-com.example.foo-random/',
       ['author-com.example.foo-random'],
       ['author-com.example.foo-random/README.txt' => 'hello']
     );
   }
 
-  public function testFindBaseDirName_0() {
+  public function testFindBaseDirName_0(): void {
     $this->_doFindBaseDirName('0/',
       ['0'],
       []
     );
   }
 
-  public function testFindBaseDirName_plainfile() {
+  public function testFindBaseDirName_plainfile(): void {
     $this->_doFindBaseDirName(FALSE,
       [],
       ['README.txt' => 'hello']
     );
   }
 
-  public function testFindBaseDirName_twodir() {
+  public function testFindBaseDirName_twodir(): void {
     $this->_doFindBaseDirName(FALSE,
       ['dir-1', 'dir-2'],
       ['dir-1/README.txt' => 'hello']
     );
   }
 
-  public function testFindBaseDirName_dirfile() {
+  public function testFindBaseDirName_dirfile(): void {
     $this->_doFindBaseDirName(FALSE,
       ['dir-1'],
       ['dir-1/README.txt' => 'hello', 'MANIFEST.MF' => 'extra']
     );
   }
 
-  public function testFindBaseDirName_dot() {
+  public function testFindBaseDirName_dot(): void {
     $this->_doFindBaseDirName(FALSE,
       ['.'],
       ['./README.txt' => 'hello']
     );
   }
 
-  public function testFindBaseDirName_dots() {
+  public function testFindBaseDirName_dots(): void {
     $this->_doFindBaseDirName(FALSE,
       ['..'],
       ['../README.txt' => 'hello']
     );
   }
 
-  public function testFindBaseDirName_weird() {
+  public function testFindBaseDirName_weird(): void {
     $this->_doFindBaseDirName(FALSE,
       ['foo/../'],
       ['foo/../README.txt' => 'hello']
     );
   }
 
-  public function testGuessBaseDir_normal() {
+  public function testGuessBaseDir_normal(): void {
     $this->_doGuessBaseDir('author-com.example.foo-random',
       ['author-com.example.foo-random'],
       ['author-com.example.foo-random/README.txt' => 'hello'],
@@ -98,7 +98,7 @@ public function testGuessBaseDir_normal() {
     );
   }
 
-  public function testGuessBaseDir_MACOSX() {
+  public function testGuessBaseDir_MACOSX(): void {
     $this->_doGuessBaseDir('com.example.foo',
       ['com.example.foo', '__MACOSX'],
       ['author-com.example.foo-random/README.txt' => 'hello', '__MACOSX/foo' => 'bar'],
@@ -106,7 +106,7 @@ public function testGuessBaseDir_MACOSX() {
     );
   }
 
-  public function testGuessBaseDir_0() {
+  public function testGuessBaseDir_0(): void {
     $this->_doGuessBaseDir('0',
       ['0'],
       [],
@@ -114,7 +114,7 @@ public function testGuessBaseDir_0() {
     );
   }
 
-  public function testGuessBaseDir_plainfile() {
+  public function testGuessBaseDir_plainfile(): void {
     $this->_doGuessBaseDir(FALSE,
       [],
       ['README.txt' => 'hello'],
@@ -122,7 +122,7 @@ public function testGuessBaseDir_plainfile() {
     );
   }
 
-  public function testGuessBaseDirTwoDir() {
+  public function testGuessBaseDirTwoDir(): void {
     $this->_doGuessBaseDir(FALSE,
       ['dir-1', 'dir-2'],
       ['dir-1/README.txt' => 'hello'],
@@ -130,7 +130,7 @@ public function testGuessBaseDirTwoDir() {
     );
   }
 
-  public function testGuessBaseDirWeird() {
+  public function testGuessBaseDirWeird(): void {
     $this->_doGuessBaseDir(FALSE,
       ['foo/../'],
       ['foo/../README.txt' => 'hello'],
diff --git a/tests/phpunit/CRM/Utils/versionCheckTest.php b/tests/phpunit/CRM/Utils/versionCheckTest.php
index 23b81ca159e8..040617db4f26 100644
--- a/tests/phpunit/CRM/Utils/versionCheckTest.php
+++ b/tests/phpunit/CRM/Utils/versionCheckTest.php
@@ -110,7 +110,7 @@ public function tearDown(): void {
     }
   }
 
-  public function testCronFallback() {
+  public function testCronFallback(): void {
     // Fake "remote" source data
     $tmpSrc = $this->tempDir . '/versionCheckTestFile.json';
     file_put_contents($tmpSrc, json_encode($this->sampleVersionInfo));
@@ -147,7 +147,7 @@ public function testCronFallback() {
     $this->assertEquals($remoteData, $vc->versionInfo);
   }
 
-  public function testGetSiteStats() {
+  public function testGetSiteStats(): void {
     // Create domain address so the domain country will come up in the stats.
     $country_params = [
       'sequential' => 1,
diff --git a/tests/phpunit/Civi/API/KernelTest.php b/tests/phpunit/Civi/API/KernelTest.php
index f5236d76cc8f..50af6ae18c14 100644
--- a/tests/phpunit/Civi/API/KernelTest.php
+++ b/tests/phpunit/Civi/API/KernelTest.php
@@ -32,7 +32,7 @@ protected function setUp(): void {
     $this->kernel = new Kernel($this->dispatcher);
   }
 
-  public function testNormalEvents() {
+  public function testNormalEvents(): void {
     $this->kernel->registerApiProvider($this->createWidgetFrobnicateProvider());
     $result = $this->kernel->runSafe('Widget', 'frobnicate', [
       'version' => self::MOCK_VERSION,
@@ -48,7 +48,7 @@ public function testNormalEvents() {
     $this->assertEquals('frob', $result['values'][98]);
   }
 
-  public function testResolveException() {
+  public function testResolveException(): void {
     $test = $this;
     $this->dispatcher->addListener('civi.api.resolve', function () {
       throw new \CRM_Core_Exception('Oh My God', 'omg', ['the' => 'badzes']);
diff --git a/tests/phpunit/Civi/API/Subscriber/DynamicFKAuthorizationTest.php b/tests/phpunit/Civi/API/Subscriber/DynamicFKAuthorizationTest.php
index f7095429b4f1..5f2e8f5ab87f 100644
--- a/tests/phpunit/Civi/API/Subscriber/DynamicFKAuthorizationTest.php
+++ b/tests/phpunit/Civi/API/Subscriber/DynamicFKAuthorizationTest.php
@@ -216,7 +216,7 @@ public function testBad($entity, $action, $params, $expectedError) {
    * Test whether trusted API calls bypass the permission check
    *
    */
-  public function testNotDelegated() {
+  public function testNotDelegated(): void {
     $entity = 'FakeFile';
     $action = 'create';
     $params = [
diff --git a/tests/phpunit/Civi/API/Subscriber/TransactionSubscriberTest.php b/tests/phpunit/Civi/API/Subscriber/TransactionSubscriberTest.php
index 706e2c0623f4..793aa856121b 100644
--- a/tests/phpunit/Civi/API/Subscriber/TransactionSubscriberTest.php
+++ b/tests/phpunit/Civi/API/Subscriber/TransactionSubscriberTest.php
@@ -107,7 +107,7 @@ public function testTransactionOptions($version, $entity, $action, $params, $isT
     $this->assertEquals($isNested, $txs->isNested($apiProvider, $apiRequest), 'check isNested');
   }
 
-  public function testForceRollback() {
+  public function testForceRollback(): void {
     $result = $this->callAPISuccess('contact', 'create', [
       'contact_type' => 'Individual',
       'first_name' => 'Me',
diff --git a/tests/phpunit/Civi/Angular/ChangeSetTest.php b/tests/phpunit/Civi/Angular/ChangeSetTest.php
index 42fc69496d64..2fda33d0e90f 100644
--- a/tests/phpunit/Civi/Angular/ChangeSetTest.php
+++ b/tests/phpunit/Civi/Angular/ChangeSetTest.php
@@ -19,7 +19,7 @@ class ChangeSetTest extends \CiviUnitTestCase {
   /**
    * Insert content using after().
    */
-  public function testInsertAfter() {
+  public function testInsertAfter(): void {
     $changeSet = ChangeSet::create(__FUNCTION__);
     $counts = ['~/foo.html' => 0];
 
@@ -49,7 +49,7 @@ public function testInsertAfter() {
   /**
    * Insert content using append() and prepend().
    */
-  public function testAppendPrepend() {
+  public function testAppendPrepend(): void {
     $changeSet = ChangeSet::create(__FUNCTION__);
     $counts = ['~/foo.html' => 0];
 
@@ -80,7 +80,7 @@ public function testAppendPrepend() {
   /**
    * Test that href expressions don't get mangled.
    */
-  public function testHrefExpressions() {
+  public function testHrefExpressions(): void {
     $changeSet = ChangeSet::create(__FUNCTION__);
     $counts = ['~/foo.html' => 0];
 
diff --git a/tests/phpunit/Civi/Angular/ManagerTest.php b/tests/phpunit/Civi/Angular/ManagerTest.php
index 6509c17865d0..a7c69be7dd4a 100644
--- a/tests/phpunit/Civi/Angular/ManagerTest.php
+++ b/tests/phpunit/Civi/Angular/ManagerTest.php
@@ -40,7 +40,7 @@ protected function setUp(): void {
   /**
    * Modules appear to be well-defined.
    */
-  public function testGetModules() {
+  public function testGetModules(): void {
     $modules = $this->angular->getModules();
 
     $counts = [
@@ -97,7 +97,7 @@ public function testGetModules() {
   /**
    * Get HTML fragments from an example module.
    */
-  public function testGetPartials() {
+  public function testGetPartials(): void {
     $partials = $this->angular->getPartials('crmMailing');
     $this->assertMatchesRegularExpression('/ng-form="crmMailingSubform">/', $partials['~/crmMailing/EditMailingCtrl/2step.html']);
     // If crmMailing changes, feel free to use a different example.
@@ -106,7 +106,7 @@ public function testGetPartials() {
   /**
    * Get HTML fragments from an example module. The HTML is modified via hook.
    */
-  public function testGetPartials_Hooked() {
+  public function testGetPartials_Hooked(): void {
     \CRM_Utils_Hook::singleton()->setHook('civicrm_alterAngular', [$this, 'hook_civicrm_alterAngular']);
 
     $partials = $this->angular->getPartials('crmMailing');
@@ -114,7 +114,7 @@ public function testGetPartials_Hooked() {
     // If crmMailing changes, feel free to use a different example.
   }
 
-  public function testGetJs_Asset() {
+  public function testGetJs_Asset(): void {
     \CRM_Utils_Hook::singleton()->setHook('civicrm_angularModules', [$this, 'hook_civicrm_angularModules_fooBar']);
 
     $paths = $this->angular->getResources(['fooBar'], 'js', 'path');
@@ -128,7 +128,7 @@ public function testGetJs_Asset() {
   /**
    * Get a translatable string from an example module.
    */
-  public function testGetStrings() {
+  public function testGetStrings(): void {
     $strings = $this->angular->getStrings('crmMailing');
     $this->assertTrue(in_array('Save Draft', $strings));
     $this->assertFalse(in_array('wild world', $strings));
@@ -138,7 +138,7 @@ public function testGetStrings() {
   /**
    * Get a translatable string from an example module. The HTML is modified via hook.
    */
-  public function testGetStrings_Hooked() {
+  public function testGetStrings_Hooked(): void {
     \CRM_Utils_Hook::singleton()->setHook('civicrm_alterAngular', [$this, 'hook_civicrm_alterAngular']);
 
     $strings = $this->angular->getStrings('crmMailing');
@@ -149,7 +149,7 @@ public function testGetStrings_Hooked() {
   /**
    * Get the list of dependencies for an Angular module.
    */
-  public function testGetRequires() {
+  public function testGetRequires(): void {
     $requires = $this->angular->getResources(['crmMailing'], 'requires', 'requires');
     $this->assertTrue(in_array('ngRoute', $requires['crmMailing']));
     $this->assertFalse(in_array('crmCatStevens', $requires['crmMailing']));
@@ -159,7 +159,7 @@ public function testGetRequires() {
   /**
    * Get the list of dependencies for an Angular module. It can be modified via hook.
    */
-  public function testGetRequires_Hooked() {
+  public function testGetRequires_Hooked(): void {
     \CRM_Utils_Hook::singleton()->setHook('civicrm_alterAngular', [$this, 'hook_civicrm_alterAngular']);
 
     $requires = $this->angular->getResources(['crmMailing'], 'requires', 'requires');
@@ -171,7 +171,7 @@ public function testGetRequires_Hooked() {
   /**
    * Get the full, recursive list of dependencies for a set of Angular modules.
    */
-  public function testResolveDeps() {
+  public function testResolveDeps(): void {
     // If crmMailing changes, feel free to use a different example.
     $expected = [
       'angularFileUpload',
diff --git a/tests/phpunit/Civi/Angular/PartialSyntaxTest.php b/tests/phpunit/Civi/Angular/PartialSyntaxTest.php
index 8886ef20215f..cce0cc8532e0 100644
--- a/tests/phpunit/Civi/Angular/PartialSyntaxTest.php
+++ b/tests/phpunit/Civi/Angular/PartialSyntaxTest.php
@@ -88,7 +88,7 @@ public function testConsistencyExamples($inputHtml, $expectHtml) {
 
   /**
    */
-  public function testAllPartials() {
+  public function testAllPartials(): void {
     $this->markTestIncomplete('checkConsistentHtml gives too many false-positive errors to be useful in a unit test.');
 
     $coder = new \Civi\Angular\Coder();
diff --git a/tests/phpunit/Civi/CCase/SequenceListenerTest.php b/tests/phpunit/Civi/CCase/SequenceListenerTest.php
index 26bddbeabb45..c5aa8681100b 100644
--- a/tests/phpunit/Civi/CCase/SequenceListenerTest.php
+++ b/tests/phpunit/Civi/CCase/SequenceListenerTest.php
@@ -24,7 +24,7 @@ public function setUp(): void {
     ]);
   }
 
-  public function testSequence() {
+  public function testSequence(): void {
     $actStatuses = array_flip(\CRM_Activity_BAO_Activity::buildOptions('status_id', 'validate'));
     $caseStatuses = array_flip(\CRM_Case_PseudoConstant::caseStatus('name'));
     $actTypes = array_flip(\CRM_Activity_BAO_Activity::buildOptions('activity_type_id', 'create'));
diff --git a/tests/phpunit/Civi/Core/CiviEventDispatcherTest.php b/tests/phpunit/Civi/Core/CiviEventDispatcherTest.php
index 135525a96e20..6854e9bc20eb 100644
--- a/tests/phpunit/Civi/Core/CiviEventDispatcherTest.php
+++ b/tests/phpunit/Civi/Core/CiviEventDispatcherTest.php
@@ -11,7 +11,7 @@
  */
 class CiviEventDispatcherTest extends \CiviUnitTestCase {
 
-  public function testDispatchPolicy_run() {
+  public function testDispatchPolicy_run(): void {
     $d = new CiviEventDispatcher(\Civi::container());
     $d->setDispatchPolicy([
       'hook_civicrm_fakeRunnable' => 'run',
@@ -24,7 +24,7 @@ public function testDispatchPolicy_run() {
     $this->assertEquals(1, $calls['hook_civicrm_fakeRunnable']);
   }
 
-  public function testDispatchPolicy_drop() {
+  public function testDispatchPolicy_drop(): void {
     $d = new CiviEventDispatcher(\Civi::container());
     $d->setDispatchPolicy([
       '/^hook_civicrm_fakeDr/' => 'drop',
@@ -37,7 +37,7 @@ public function testDispatchPolicy_drop() {
     $this->assertTrue(!isset($calls['hook_civicrm_fakeDroppable']));
   }
 
-  public function testDispatchPolicy_fail() {
+  public function testDispatchPolicy_fail(): void {
     $d = new CiviEventDispatcher(\Civi::container());
     $d->setDispatchPolicy([
       '/^hook_civicrm_fakeFa/' => 'fail',
diff --git a/tests/phpunit/Civi/Core/CiviEventInspectorTest.php b/tests/phpunit/Civi/Core/CiviEventInspectorTest.php
index a58221519711..3359d21fe253 100644
--- a/tests/phpunit/Civi/Core/CiviEventInspectorTest.php
+++ b/tests/phpunit/Civi/Core/CiviEventInspectorTest.php
@@ -7,7 +7,7 @@
  */
 class CiviEventInspectorTest extends \CiviUnitTestCase {
 
-  public function testGet() {
+  public function testGet(): void {
     $inspector = new CiviEventInspector();
     $eventDef = $inspector->get('hook_civicrm_alterSettingsMetaData');
     $this->assertEquals('hook_civicrm_alterSettingsMetaData', $eventDef['name']);
@@ -22,7 +22,7 @@ public function testGet() {
     $this->assertTrue($eventDef['stub']->isStatic());
   }
 
-  public function testGetAll() {
+  public function testGetAll(): void {
     $inspector = new CiviEventInspector();
     $all = $inspector->getAll();
     $this->assertTrue(count($all) > 1);
@@ -37,7 +37,7 @@ public function testGetAll() {
     }
   }
 
-  public function testFind() {
+  public function testFind(): void {
     $inspector = new CiviEventInspector();
 
     $result_a = $inspector->find('/^hook_civicrm_post/');
diff --git a/tests/phpunit/Civi/Core/CiviFacadeTest.php b/tests/phpunit/Civi/Core/CiviFacadeTest.php
index 645937a087b2..544fb2d7660c 100644
--- a/tests/phpunit/Civi/Core/CiviFacadeTest.php
+++ b/tests/phpunit/Civi/Core/CiviFacadeTest.php
@@ -24,7 +24,7 @@ public function tearDown(): void {
   /**
    * Get the the settingsbag for a logged-in user.
    */
-  public function testContactSettings_loggedIn() {
+  public function testContactSettings_loggedIn(): void {
     $this->createLoggedInUser();
     $settingsBag = \Civi::contactSettings();
     $settingsBag->set('foo', 'bar');
@@ -34,7 +34,7 @@ public function testContactSettings_loggedIn() {
   /**
    * Anonymous users don't have a SettingsBag.
    */
-  public function testContactSettings_anonFail() {
+  public function testContactSettings_anonFail(): void {
     $this->expectException(\CRM_Core_Exception::class);
     \Civi::contactSettings();
   }
@@ -42,7 +42,7 @@ public function testContactSettings_anonFail() {
   /**
    * Get the SettingsBag for a specific user.
    */
-  public function testContactSettings_byId() {
+  public function testContactSettings_byId(): void {
     $cid = \CRM_Core_DAO::singleValueQuery('SELECT MIN(id) FROM civicrm_contact');
     $settingsBag = \Civi::contactSettings($cid);
     $settingsBag->set('foo', 'bar');
diff --git a/tests/phpunit/Civi/Core/Event/GenericHookEventTest.php b/tests/phpunit/Civi/Core/Event/GenericHookEventTest.php
index 85971846ae10..4557cab529b3 100644
--- a/tests/phpunit/Civi/Core/Event/GenericHookEventTest.php
+++ b/tests/phpunit/Civi/Core/Event/GenericHookEventTest.php
@@ -8,7 +8,7 @@ public function tearDown(): void {
     parent::tearDown();
   }
 
-  public function testConstructParams() {
+  public function testConstructParams(): void {
     $event = GenericHookEvent::create([
       'ab' => 123,
       'cd' => ['foo' => 'bar'],
@@ -25,7 +25,7 @@ public function testConstructParams() {
     $this->assertTrue(isset($event->nothingZero) && empty($event->nothingZero));
   }
 
-  public function testConstructOrdered() {
+  public function testConstructOrdered(): void {
     $null = NULL;
     $event = GenericHookEvent::createOrdered(
       ['alpha', 'beta', 'nothingNull', 'nothingZero'],
@@ -42,7 +42,7 @@ public function testConstructOrdered() {
     $this->assertEquals(4, count($event->getHookValues()));
   }
 
-  public function testDispatch() {
+  public function testDispatch(): void {
     \CRM_Utils_Hook::singleton()->setHook('civicrm_ghet',
       [$this, 'hook_civicrm_ghet']);
     \Civi::dispatcher()->addListener('hook_civicrm_ghet',
diff --git a/tests/phpunit/Civi/Core/Event/HookStyleServiceListenerTest.php b/tests/phpunit/Civi/Core/Event/HookStyleServiceListenerTest.php
index 4e5154316cd0..56a83f813bdd 100644
--- a/tests/phpunit/Civi/Core/Event/HookStyleServiceListenerTest.php
+++ b/tests/phpunit/Civi/Core/Event/HookStyleServiceListenerTest.php
@@ -17,7 +17,7 @@ public function tearDown(): void {
     parent::tearDown();
   }
 
-  public function testDispatch() {
+  public function testDispatch(): void {
     $changeMe = $rand = rand(0, 16384);
 
     $this->useCustomContainer(function (ContainerBuilder $container) use ($rand) {
diff --git a/tests/phpunit/Civi/Core/Event/ServiceListenerTest.php b/tests/phpunit/Civi/Core/Event/ServiceListenerTest.php
index 0cf534b175f8..6dbb53d72492 100644
--- a/tests/phpunit/Civi/Core/Event/ServiceListenerTest.php
+++ b/tests/phpunit/Civi/Core/Event/ServiceListenerTest.php
@@ -12,7 +12,7 @@ public function tearDown(): void {
     parent::tearDown();
   }
 
-  public function testDispatch() {
+  public function testDispatch(): void {
     $changeMe = $rand = rand(0, 16384);
 
     $container = new ContainerBuilder();
diff --git a/tests/phpunit/Civi/Core/PathsTest.php b/tests/phpunit/Civi/Core/PathsTest.php
index 7415442386b6..7a69df1fddf9 100644
--- a/tests/phpunit/Civi/Core/PathsTest.php
+++ b/tests/phpunit/Civi/Core/PathsTest.php
@@ -92,7 +92,7 @@ public function testExamples($varName, $varType, $varValue, $inputExpr, $expectV
     unset($civicrm_paths[$varName][$varType]);
   }
 
-  public function testGetUrl_ImplicitBase() {
+  public function testGetUrl_ImplicitBase(): void {
     $p = \Civi::paths();
     $cmsRoot = rtrim($p->getVariable('cms.root', 'url'), '/');
 
@@ -104,7 +104,7 @@ public function testGetUrl_ImplicitBase() {
   /**
    * This test demonstrates how to (and how not to) compute a derivative path variable.
    */
-  public function testAbsoluteRelativeConversions() {
+  public function testAbsoluteRelativeConversions(): void {
     $gstack = \CRM_Utils_GlobalStack::singleton();
     $gstack->push(['_SERVER' => ['HTTP_HOST' => 'example.com']]);
     $cleanup = \CRM_Utils_AutoClean::with([$gstack, 'pop']);
diff --git a/tests/phpunit/Civi/Core/ResolverTest.php b/tests/phpunit/Civi/Core/ResolverTest.php
index 3a4a4373fb20..d328e87bdd03 100644
--- a/tests/phpunit/Civi/Core/ResolverTest.php
+++ b/tests/phpunit/Civi/Core/ResolverTest.php
@@ -25,7 +25,7 @@ protected function setUp(): void {
     /**
      * Test callback with a constant value.
      */
-    public function testConstant() {
+    public function testConstant(): void {
       $cb = $this->resolver->get('0');
       $actual = call_user_func($cb, 'foo');
       $this->assertTrue(0 === $actual);
@@ -38,7 +38,7 @@ public function testConstant() {
     /**
      * Test callback for a global function.
      */
-    public function testGlobalFunc() {
+    public function testGlobalFunc(): void {
       // Note: civi_core_callback_dummy is implemented at the bottom of this file.
       $cb = $this->resolver->get('civi_core_callback_dummy');
       $this->assertEquals('civi_core_callback_dummy', $cb);
@@ -51,7 +51,7 @@ public function testGlobalFunc() {
     /**
      * Test callback for a static function.
      */
-    public function testStatic() {
+    public function testStatic(): void {
       $cb = $this->resolver->get('Civi\Core\ResolverTest::dummy');
       $this->assertEquals(['Civi\Core\ResolverTest', 'dummy'], $cb);
 
@@ -63,7 +63,7 @@ public function testStatic() {
     /**
      * Test callback for an API.
      */
-    public function testApi3() {
+    public function testApi3(): void {
       // Note: The Resolvertest.Ping API is implemented at the bottom of this file.
       $cb = $this->resolver->get('api3://Resolvertest/ping?first=@1');
       $expected = 'api dummy received foo';
@@ -74,7 +74,7 @@ public function testApi3() {
     /**
      * Test callback for an object in the container.
      */
-    public function testCall() {
+    public function testCall(): void {
       // Note: ResolverTestExampleService is implemented at the bottom of this file.
       \Civi::container()->set('callbackTestService', new ResolverTestExampleService());
       $cb = $this->resolver->get('call://callbackTestService/ping');
@@ -86,7 +86,7 @@ public function testCall() {
     /**
      * Test callback for an invalid object in the container.
      */
-    public function testCallWithInvalidService() {
+    public function testCallWithInvalidService(): void {
       $this->expectException(\Symfony\Component\DependencyInjection\Exception\ExceptionInterface::class);
       $this->resolver->get('call://totallyNonexistentService/ping');
     }
@@ -94,7 +94,7 @@ public function testCallWithInvalidService() {
     /**
      * Test callback which returns a global variable.
      */
-    public function testGlobalGetter() {
+    public function testGlobalGetter(): void {
       $_GET['resolverTest'] = 123;
       $cb = $this->resolver->get('global://_GET/resolverTest?getter');
       $_GET['resolverTest'] = 456;
@@ -103,7 +103,7 @@ public function testGlobalGetter() {
       unset($_GET['resolverTest']);
     }
 
-    public function testGlobalSetter() {
+    public function testGlobalSetter(): void {
       $GLOBALS['resolverTest2'] = 78;
       $cb = $this->resolver->get('global://resolverTest2?setter');
       call_user_func($cb, 90);
@@ -113,7 +113,7 @@ public function testGlobalSetter() {
     /**
      * Test object-lookup in the container.
      */
-    public function testObj() {
+    public function testObj(): void {
       // Note: ResolverTestExampleService is implemented at the bottom of this file.
       \Civi::container()->set('callbackTestService', new ResolverTestExampleService());
       $obj = $this->resolver->get('obj://callbackTestService');
@@ -123,7 +123,7 @@ public function testObj() {
     /**
      * Test object-lookup in the container (invalid name).
      */
-    public function testObjWithInvalidService() {
+    public function testObjWithInvalidService(): void {
       $this->expectException(\Symfony\Component\DependencyInjection\Exception\ExceptionInterface::class);
       $this->resolver->get('obj://totallyNonexistentService');
     }
@@ -131,7 +131,7 @@ public function testObjWithInvalidService() {
     /**
      * Test default object creation.
      */
-    public function testClass() {
+    public function testClass(): void {
       // Note: ResolverTestExampleService is implemented at the bottom of this file.
       $obj = $this->resolver->get('Civi\Core\ResolverTestExampleService');
       $this->assertTrue($obj instanceof ResolverTestExampleService);
diff --git a/tests/phpunit/Civi/Core/Service/AutoDefinitionTest.php b/tests/phpunit/Civi/Core/Service/AutoDefinitionTest.php
index cd5850722c41..2947df817d91 100644
--- a/tests/phpunit/Civi/Core/Service/AutoDefinitionTest.php
+++ b/tests/phpunit/Civi/Core/Service/AutoDefinitionTest.php
@@ -36,7 +36,7 @@ protected function setUp(): void {
   /**
    * A property with the `@inject` annotation will receive a service with the matching name.
    */
-  public function testInjectEponymousProperty() {
+  public function testInjectEponymousProperty(): void {
     $this->useExampleService(
       /**
        * @service TestEponymousProperty
@@ -59,7 +59,7 @@ public function testInjectEponymousProperty() {
   /**
    * A property with the `@inject` annotation can be private.
    */
-  public function testInjectPrivateProperty() {
+  public function testInjectPrivateProperty(): void {
     $this->useExampleService(
       /**
        * @service TestInjectPrivateProperty
@@ -84,7 +84,7 @@ public function testInjectPrivateProperty() {
   /**
    * A property with `@inject <my.service.name>` will receive the named service.
    */
-  public function testInjectNamedProperty() {
+  public function testInjectNamedProperty(): void {
     $this->useExampleService(
       /**
        * @service TestNamedProperty
@@ -109,7 +109,7 @@ public function testInjectNamedProperty() {
    * A method `setFooBar()` with `@inject <my.service.name>` will be called during initialization
    * with the requested service.
    */
-  public function testInjectSetter() {
+  public function testInjectSetter(): void {
     $this->useExampleService(
       /**
        * @service TestInjectSetter
@@ -146,7 +146,7 @@ public function setLog(?\Psr\Log\LoggerInterface $log): void {
   /**
    * A constructor with `@inject <my.service.name>` will be called with the requested service.
    */
-  public function testInjectConstructor() {
+  public function testInjectConstructor(): void {
     $this->useExampleService(
       /**
        * @service TestInjectConstructor
@@ -188,7 +188,7 @@ public function __construct(?\Psr\Log\LoggerInterface $log = NULL, ?\Psr\SimpleC
    * Note, however, that upstream doesn't guarantee the sequence over the long-term.
    * If it changes, you may need to update the test.
    */
-  public function testInjectionSequence() {
+  public function testInjectionSequence(): void {
     $this->useExampleService(
       /**
        * @service TestInjectionSequence
@@ -274,7 +274,7 @@ public function getFilledFields(): array {
    * In this example, we create two services (each with a different factory method, and each
    * with a different kind of data).
    */
-  public function testFactoryMethods() {
+  public function testFactoryMethods(): void {
     $this->useExampleService(
       new class() {
 
@@ -326,7 +326,7 @@ public static function dynamicFactory(?\Psr\Log\LoggerInterface $log = NULL) {
    * What happens if you have multiple `@service` definitions (one on the class, one on a factory-method)?
    * You get multiple services.
    */
-  public function testClassAndFactoryMix() {
+  public function testClassAndFactoryMix(): void {
     $this->useExampleService(
       /**
        * @service TestClassAndFactoryMix.normal
@@ -380,7 +380,7 @@ public static function dynamicFactory(?\Psr\Log\LoggerInterface $log = NULL) {
    *
    * In this example, we make two instances. Each instance has a different value for `$myName`.
    */
-  public function testTwoManualServices() {
+  public function testTwoManualServices(): void {
     $this->useCustomContainer(function(ContainerBuilder $container) {
       $exemplar = new class() implements AutoServiceInterface {
 
diff --git a/tests/phpunit/Civi/Core/SettingsBagTest.php b/tests/phpunit/Civi/Core/SettingsBagTest.php
index 69f58dfcb59f..635f42ddfb4d 100644
--- a/tests/phpunit/Civi/Core/SettingsBagTest.php
+++ b/tests/phpunit/Civi/Core/SettingsBagTest.php
@@ -24,7 +24,7 @@ public function tearDown(): void {
   /**
    * CRM-19610 - Ensure InnoDb FTS doesn't break search preferenes when disabled.
    */
-  public function testInnoDbFTS() {
+  public function testInnoDbFTS(): void {
 
     $settingsBag = \Civi::settings();
 
@@ -36,7 +36,7 @@ public function testInnoDbFTS() {
    * The setting "contribution_invoice_settings" is actually a virtual value built on other settings.
    * Check that various updates work as expected.
    */
-  public function testVirtualContributionSetting_explicit() {
+  public function testVirtualContributionSetting_explicit(): void {
     $s = \Civi::settings();
 
     $this->assertEquals(10, $s->get('contribution_invoice_settings')['due_date']);
@@ -65,7 +65,7 @@ public function testVirtualContributionSetting_explicit() {
    * The setting "contribution_invoice_settings" is actually a virtual value built on other settings.
    * Check that mandatory values ($civicrm_settings) are respected.
    */
-  public function testVirtualContributionSetting_mandatory() {
+  public function testVirtualContributionSetting_mandatory(): void {
     $s = \Civi::settings();
     $this->assertEquals(10, $s->get('contribution_invoice_settings')['due_date']);
     $this->assertEquals(10, $s->get('invoice_due_date'));
diff --git a/tests/phpunit/Civi/Core/SettingsManagerTest.php b/tests/phpunit/Civi/Core/SettingsManagerTest.php
index 344d28ddf881..01656e48f3df 100644
--- a/tests/phpunit/Civi/Core/SettingsManagerTest.php
+++ b/tests/phpunit/Civi/Core/SettingsManagerTest.php
@@ -46,7 +46,7 @@ public function tearDown(): void {
   /**
    * Test mingled reads/writes of settings for two different domains.
    */
-  public function testTwoDomains() {
+  public function testTwoDomains(): void {
     $da = \CRM_Core_DAO::createTestObject('CRM_Core_DAO_Domain');
     $db = \CRM_Core_DAO::createTestObject('CRM_Core_DAO_Domain');
 
@@ -74,7 +74,7 @@ public function testTwoDomains() {
   /**
    * Test mingled reads/writes of settings for two different contacts.
    */
-  public function testTwoContacts() {
+  public function testTwoContacts(): void {
     $domain = \CRM_Core_DAO::createTestObject('CRM_Core_DAO_Domain');
     $ca = \CRM_Core_DAO::createTestObject('CRM_Contact_DAO_Contact');
     $cb = \CRM_Core_DAO::createTestObject('CRM_Contact_DAO_Contact');
@@ -101,7 +101,7 @@ public function testTwoContacts() {
     $this->assertEquals('GAMMA MAN!', $caSettingsRedux->get('c3'));
   }
 
-  public function testCrossOver() {
+  public function testCrossOver(): void {
     $domain = \CRM_Core_DAO::createTestObject('CRM_Core_DAO_Domain');
     $contact = \CRM_Core_DAO::createTestObject('CRM_Contact_DAO_Contact');
 
@@ -146,7 +146,7 @@ protected function createManager() {
   /**
    * Test passing in an array to Civi::settings facade
    */
-  public function testArraySetting() {
+  public function testArraySetting(): void {
     $domain = \CRM_Core_DAO::createTestObject('CRM_Core_DAO_Domain');
 
     $manager = $this->createManager()->useDefaults();
diff --git a/tests/phpunit/Civi/Core/SettingsStackTest.php b/tests/phpunit/Civi/Core/SettingsStackTest.php
index 258c68d20e16..73b70ae218ab 100644
--- a/tests/phpunit/Civi/Core/SettingsStackTest.php
+++ b/tests/phpunit/Civi/Core/SettingsStackTest.php
@@ -11,7 +11,7 @@ protected function setUp(): void {
   /**
    * Temporarily modify -- then restore -- settings.
    */
-  public function testStack() {
+  public function testStack(): void {
     $origVal = \Civi::settings()->get('show_events');
 
     $settingsStack = new \Civi\Core\SettingsStack();
diff --git a/tests/phpunit/Civi/Core/SettingsStyleTest.php b/tests/phpunit/Civi/Core/SettingsStyleTest.php
index 2c674abd38f1..041e09162259 100644
--- a/tests/phpunit/Civi/Core/SettingsStyleTest.php
+++ b/tests/phpunit/Civi/Core/SettingsStyleTest.php
@@ -11,7 +11,7 @@ protected function setUp(): void {
   /**
    * Scan all known settings
    */
-  public function testConformance() {
+  public function testConformance(): void {
     $errors = [];
     $assert = function (string $setting, bool $condition, string $message) use (&$errors) {
       if (!$condition) {
diff --git a/tests/phpunit/Civi/Core/ThemesTest.php b/tests/phpunit/Civi/Core/ThemesTest.php
index 03f2691acd9a..3bbf8d31d2e6 100644
--- a/tests/phpunit/Civi/Core/ThemesTest.php
+++ b/tests/phpunit/Civi/Core/ThemesTest.php
@@ -195,19 +195,19 @@ public static function fakeCallback($themes, $themeKey, $cssExt, $cssFile) {
     return $map[$themeKey][$cssExt][$cssFile] ?? Themes::PASSTHRU;
   }
 
-  public function testGetAll() {
+  public function testGetAll(): void {
     $all = \Civi::service('themes')->getAll();
     $this->assertTrue(isset($all['greenwich']));
     $this->assertTrue(isset($all['_fallback_']));
   }
 
-  public function testGetAvailable() {
+  public function testGetAvailable(): void {
     $all = \Civi::service('themes')->getAvailable();
     $this->assertTrue(isset($all['greenwich']));
     $this->assertFalse(isset($all['_fallback_']));
   }
 
-  public function testApiOptions() {
+  public function testApiOptions(): void {
     $result = $this->callAPISuccess('Setting', 'getoptions', [
       'field' => 'theme_backend',
     ]);
diff --git a/tests/phpunit/Civi/Crypto/CryptoJwtTest.php b/tests/phpunit/Civi/Crypto/CryptoJwtTest.php
index c5fa1a2e9d4a..56c6d743a97a 100644
--- a/tests/phpunit/Civi/Crypto/CryptoJwtTest.php
+++ b/tests/phpunit/Civi/Crypto/CryptoJwtTest.php
@@ -28,7 +28,7 @@ protected function setUp(): void {
     JWT::$timestamp = NULL;
   }
 
-  public function testSignVerifyExpire() {
+  public function testSignVerifyExpire(): void {
     /** @var \Civi\Crypto\CryptoJwt $cryptoJwt */
     $cryptoJwt = \Civi::service('crypto.jwt');
 
@@ -94,7 +94,7 @@ public function testSignMixKeys($encKey, $decKey, $expectOk) {
     }
   }
 
-  public function testSuiteToAlg() {
+  public function testSuiteToAlg(): void {
     $this->assertEquals('HS256', Invasive::call([CryptoJwt::class, 'suiteToAlg'], ['jwt-hs256']));
     $this->assertEquals(NULL, Invasive::call([CryptoJwt::class, 'suiteToAlg'], ['aes-cbc']));
   }
diff --git a/tests/phpunit/Civi/Crypto/CryptoRegistryTest.php b/tests/phpunit/Civi/Crypto/CryptoRegistryTest.php
index 2cdea071bec8..b2fb69dfc7c5 100644
--- a/tests/phpunit/Civi/Crypto/CryptoRegistryTest.php
+++ b/tests/phpunit/Civi/Crypto/CryptoRegistryTest.php
@@ -25,7 +25,7 @@ protected function setUp(): void {
     \CRM_Utils_Hook::singleton()->setHook('civicrm_crypto', [$this, 'registerExampleKeys']);
   }
 
-  public function testParseKey() {
+  public function testParseKey(): void {
     $examples = self::getExampleKeys();
     $registry = \Civi::service('crypto.registry');
 
@@ -49,7 +49,7 @@ public function testParseKey() {
     $this->assertEquals('0ao5eC7C/rwwk2qii4oLd6eG3KJq8ZDX2K9zWbvaLdo=', base64_encode($key3['key']));
   }
 
-  public function testRegisterAndFindKeys() {
+  public function testRegisterAndFindKeys(): void {
     /** @var CryptoRegistry $registry */
     $registry = \Civi::service('crypto.registry');
 
@@ -74,7 +74,7 @@ public function testRegisterAndFindKeys() {
     $this->assertEquals('asdf-key-1', $key['id']);
   }
 
-  public function testValidKeyId() {
+  public function testValidKeyId(): void {
     $valids = ['abc', 'a.b-c_d+e/', 'f\\g:h;i='];
     $invalids = [chr(0), chr(1), chr(1) . 'abc', 'a b', "ab\n", "ab\nc", "\r", "\n"];
 
@@ -90,7 +90,7 @@ public function testValidKeyId() {
     }
   }
 
-  public function testAddBadKeyId() {
+  public function testAddBadKeyId(): void {
     /** @var CryptoRegistry $registry */
     $registry = \Civi::service('crypto.registry');
 
diff --git a/tests/phpunit/Civi/Crypto/CryptoTokenTest.php b/tests/phpunit/Civi/Crypto/CryptoTokenTest.php
index 87d928c98e27..ada10ef09d85 100644
--- a/tests/phpunit/Civi/Crypto/CryptoTokenTest.php
+++ b/tests/phpunit/Civi/Crypto/CryptoTokenTest.php
@@ -25,7 +25,7 @@ protected function setUp(): void {
     \CRM_Utils_Hook::singleton()->setHook('civicrm_crypto', [$this, 'registerExampleKeys']);
   }
 
-  public function testIsPlainText() {
+  public function testIsPlainText(): void {
     $token = \Civi::service('crypto.token');
 
     $this->assertFalse($token->isPlainText(chr(2)));
@@ -37,7 +37,7 @@ public function testIsPlainText() {
     $this->assertTrue($token->isPlainText("\n"));
   }
 
-  public function testDecryptInvalid() {
+  public function testDecryptInvalid(): void {
     $cryptoToken = \Civi::service('crypto.token');
     try {
       $cryptoToken->decrypt(chr(2) . 'CTK0' . chr(2));
@@ -92,7 +92,7 @@ public function testRoundtrip($inputText, $inputKeyIdOrTag, $expectTokenRegex, $
     $this->assertEquals($inputText, $actualText);
   }
 
-  public function testRekeyCiphertext() {
+  public function testRekeyCiphertext(): void {
     /** @var \Civi\Crypto\CryptoRegistry $cryptoRegistry */
     $cryptoRegistry = \Civi::service('crypto.registry');
     /** @var \Civi\Crypto\CryptoToken $cryptoToken */
@@ -118,7 +118,7 @@ public function testRekeyCiphertext() {
     $this->assertEquals('hello world', $cryptoToken->decrypt($third));
   }
 
-  public function testRekeyUpgradeDowngradePlaintext() {
+  public function testRekeyUpgradeDowngradePlaintext(): void {
     /** @var \Civi\Crypto\CryptoRegistry $cryptoRegistry */
     $cryptoRegistry = \Civi::service('crypto.registry');
     /** @var \Civi\Crypto\CryptoToken $cryptoToken */
@@ -152,7 +152,7 @@ public function testRekeyUpgradeDowngradePlaintext() {
 
   }
 
-  public function testReadPlainTextWithoutRegistry() {
+  public function testReadPlainTextWithoutRegistry(): void {
     // This is performance optimization - don't initialize crypto.registry unless
     // you actually need it.
     $this->assertFalse(\Civi::container()->initialized('crypto.registry'));
diff --git a/tests/phpunit/Civi/Payment/PropertyBagTest.php b/tests/phpunit/Civi/Payment/PropertyBagTest.php
index 846a5eaa87f6..29e930cb8a87 100644
--- a/tests/phpunit/Civi/Payment/PropertyBagTest.php
+++ b/tests/phpunit/Civi/Payment/PropertyBagTest.php
@@ -23,7 +23,7 @@ public function setUpHeadless() {
   /**
    * Test we can set a contact ID.
    */
-  public function testSetContactID() {
+  public function testSetContactID(): void {
     // Do things proper.
     $propertyBag = new PropertyBag();
     $propertyBag->setContactID(123);
@@ -97,7 +97,7 @@ public function setAmountDataProvider() {
   /**
    * Test we cannot set an invalid contact ID.
    */
-  public function testSetContactIDFailsIfInvalid() {
+  public function testSetContactIDFailsIfInvalid(): void {
     $this->expectException(\InvalidArgumentException::class);
     $propertyBag = new PropertyBag();
     $propertyBag->setContactID(0);
@@ -106,7 +106,7 @@ public function testSetContactIDFailsIfInvalid() {
   /**
    * Test we can set a contact ID the wrong way
    */
-  public function testSetContactIDLegacyWay() {
+  public function testSetContactIDLegacyWay(): void {
     $propertyBag = new PropertyBag();
     $propertyBag->setSuppressLegacyWarnings(FALSE);
 
@@ -148,7 +148,7 @@ public function testSetContactIDLegacyWay() {
   /**
    * Test that emails set by the legacy method of 'email-5' can be retrieved with getEmail.
    */
-  public function testSetBillingEmailLegacy() {
+  public function testSetBillingEmailLegacy(): void {
     $localPropertyBag = PropertyBag::cast(['email-' . \CRM_Core_BAO_LocationType::getBilling() => 'a@b.com']);
     $this->assertEquals('a@b.com', $localPropertyBag->getEmail());
   }
@@ -158,7 +158,7 @@ public function testSetBillingEmailLegacy() {
    *
    * See https://github.com/civicrm/civicrm-core/pull/17292
    */
-  public function testRecurProcessorIDNull() {
+  public function testRecurProcessorIDNull(): void {
     $bag = new PropertyBag();
     $bag->setRecurProcessorID(NULL);
     $value = $bag->getRecurProcessorID();
@@ -167,7 +167,7 @@ public function testRecurProcessorIDNull() {
 
   /**
    */
-  public function testMergeInputs() {
+  public function testMergeInputs(): void {
     $propertyBag = PropertyBag::cast([
       'contactID' => 123,
       'contributionRecurID' => 456,
@@ -179,7 +179,7 @@ public function testMergeInputs() {
   /**
    * Test we can set and access custom props.
    */
-  public function testSetCustomProp() {
+  public function testSetCustomProp(): void {
     $oldLevel = error_reporting();
     $ignoreUserDeprecatedErrors = $oldLevel & ~E_USER_DEPRECATED;
 
@@ -225,7 +225,7 @@ public function testSetCustomProp() {
   /**
    * Test we can't set a custom prop that we know about.
    */
-  public function testSetCustomPropFails() {
+  public function testSetCustomPropFails(): void {
     $this->expectException(\InvalidArgumentException::class);
     $this->expectExceptionMessage('Attempted to set \'contactID\' via setCustomProperty - must use using its setter.');
     $propertyBag = new PropertyBag();
@@ -237,7 +237,7 @@ public function testSetCustomPropFails() {
    *
    * This is only for backward compatibility/ease of transition. One day it would be nice to throw an exception instead.
    */
-  public function testGetCustomPropFails() {
+  public function testGetCustomPropFails(): void {
     $this->expectException(\BadMethodCallException::class);
     $this->expectExceptionMessage('Property \'aCustomProp\' has not been set.');
     $propertyBag = new PropertyBag();
@@ -325,7 +325,7 @@ public function testOtherParams($prop, $legacy_names, $valid_values, $invalid_va
   /**
    * Test the require method works.
    */
-  public function testRequire() {
+  public function testRequire(): void {
     $propertyBag = new PropertyBag();
     $propertyBag->setContactID(123);
     $propertyBag->setDescription('foo');
@@ -342,7 +342,7 @@ public function testRequire() {
   /**
    * Test retrieves using CRM_Utils_Array::value still work.
    */
-  public function testUtilsArray() {
+  public function testUtilsArray(): void {
     $propertyBag = new PropertyBag();
     $propertyBag->setContactID(123);
     // This will throw deprecation notices but we don't care.
@@ -358,7 +358,7 @@ public function testUtilsArray() {
 
   /**
    */
-  public function testEmpty() {
+  public function testEmpty(): void {
     $propertyBag = new PropertyBag();
     $propertyBag->setContactID(123);
     $propertyBag->setRecurProcessorID('');
@@ -450,7 +450,7 @@ public function otherParamsDataProvider() {
   /**
    * Billing country is a mess.
    */
-  public function testBillingCountry() {
+  public function testBillingCountry(): void {
 
     // Test designed use
     foreach (['NZ', 'GB'] as $valid) {
@@ -521,7 +521,7 @@ public function testBillingCountry() {
    * Test generic getter, setter methods.
    *
    */
-  public function testGetterAndSetter() {
+  public function testGetterAndSetter(): void {
     $propertyBag = new PropertyBag();
 
     $propertyBag->setter('contactID', 123);
diff --git a/tests/phpunit/Civi/Pipe/JsonRpcSessionTest.php b/tests/phpunit/Civi/Pipe/JsonRpcSessionTest.php
index 594118b311ce..9f89fe807fcb 100644
--- a/tests/phpunit/Civi/Pipe/JsonRpcSessionTest.php
+++ b/tests/phpunit/Civi/Pipe/JsonRpcSessionTest.php
@@ -36,7 +36,7 @@ protected function tearDown(): void {
     parent::tearDown();
   }
 
-  public function testInvalid_BadMethod() {
+  public function testInvalid_BadMethod(): void {
     $responseLines = $this->runLines([
       '{"jsonrpc":"2.0","method":"wiggum"}',
     ]);
@@ -46,7 +46,7 @@ public function testInvalid_BadMethod() {
     $this->assertEquals(-32601, $decode['error']['code']);
   }
 
-  public function testInvalid_MalformedParams() {
+  public function testInvalid_MalformedParams(): void {
     $responseLines = $this->runLines([
       '{"jsonrpc":"2.0","id":"a","method":"echo","params":123}',
     ]);
@@ -56,7 +56,7 @@ public function testInvalid_MalformedParams() {
     $this->assertEquals(-32602, $decode['error']['code']);
   }
 
-  public function testEcho() {
+  public function testEcho(): void {
     $this->assertRequestResponse([
       '{"jsonrpc":"2.0","id":null,"method":"echo"}' => '{"jsonrpc":"2.0","result":[],"id":null}',
       '{"jsonrpc":"2.0","id":"a","method":"echo","params":{"color":"blue"}}' => '{"jsonrpc":"2.0","result":{"color":"blue"},"id":"a"}',
@@ -65,7 +65,7 @@ public function testEcho() {
     ]);
   }
 
-  public function testBatch() {
+  public function testBatch(): void {
     $batchLine = '[' .
       '{"jsonrpc":"2.0","id":"a","method":"wiggum"},' .
       '{"jsonrpc":"2.0","id":"b","method": "echo","params":[123]}' .
@@ -83,14 +83,14 @@ public function testBatch() {
     $this->assertEquals([123], $decode[1]['result']);
   }
 
-  public function testInvalidControl() {
+  public function testInvalidControl(): void {
     $responses = $this->runLines(['{"jsonrpc":"2.0","id":"b","method":"session.nope","params":[]}']);
     $decode = json_decode($responses[1], 1);
     $this->assertEquals('2.0', $decode['jsonrpc']);
     $this->assertEquals('Method not found', $decode['error']['message']);
   }
 
-  public function testControl() {
+  public function testControl(): void {
     $this->assertRequestResponse([
       '{"jsonrpc":"2.0","id":"c","method":"options"}' => '{"jsonrpc":"2.0","result":{"apiCheckPermissions":true,"apiError":"exception","bufferSize":524288,"responsePrefix":null},"id":"c"}',
       '{"jsonrpc":"2.0","id":"c","method":"options","params":{"responsePrefix":"ZZ"}}' => 'ZZ{"jsonrpc":"2.0","result":{"responsePrefix":"ZZ"},"id":"c"}',
@@ -98,7 +98,7 @@ public function testControl() {
     ]);
   }
 
-  public function testApi3() {
+  public function testApi3(): void {
     $responses = $this->runLines(['{"jsonrpc":"2.0","id":"a3","method":"api3","params":["System","get"]}']);
 
     $this->assertEquals($this->standardHeader, $responses[0]);
@@ -109,7 +109,7 @@ public function testApi3() {
     $this->assertEquals(\CRM_Utils_System::version(), $decode['result']['values'][0]['version']);
   }
 
-  public function testApi3ErrorModes() {
+  public function testApi3ErrorModes(): void {
     $responses = $this->runLines([
       // First call: By default, use JSON-RPC errors.
       '{"jsonrpc":"2.0","id":"bad1","method":"api3","params":["System","zznnzznnzz"]}',
@@ -137,7 +137,7 @@ public function testApi3ErrorModes() {
     $this->assertMatchesRegularExpression(';API.*System.*zznnzznnzz.*not exist;', $decode['result']['error_message']);
   }
 
-  public function testApi4() {
+  public function testApi4(): void {
     $responses = $this->runLines(['{"jsonrpc":"2.0","id":"a4","method":"api4","params":["Contact","getFields"]}']);
 
     $this->assertEquals($this->standardHeader, $responses[0]);
@@ -150,7 +150,7 @@ public function testApi4() {
     $this->assertEquals('Number', $fields['id']['input_type']);
   }
 
-  public function testApi4Authz() {
+  public function testApi4Authz(): void {
     // We try 'Route.get' action with different access levels.
     $useException = '{"jsonrpc":"2.0","id":"o","method":"options","params":{"apiError":"exception"}}';
     $checkPermTrue = '{"jsonrpc":"2.0","id":"m","method":"api4","params":["Route","get",{"checkPermissions":true}]}';
@@ -198,7 +198,7 @@ public function testApi4Authz() {
     }
   }
 
-  public function testApi4ErrorModes() {
+  public function testApi4ErrorModes(): void {
     $responses = $this->runLines([
       // First call: By default, use JSON-RPC errors.
       '{"jsonrpc":"2.0","id":"bad1","method":"api4","params":["System","zznnzznnzz"]}',
diff --git a/tests/phpunit/Civi/Report/OutputHandlerFactoryTest.php b/tests/phpunit/Civi/Report/OutputHandlerFactoryTest.php
index 78397cdd8fcd..6fc48430aa22 100644
--- a/tests/phpunit/Civi/Report/OutputHandlerFactoryTest.php
+++ b/tests/phpunit/Civi/Report/OutputHandlerFactoryTest.php
@@ -11,7 +11,7 @@ class OutputHandlerFactoryTest extends \CiviUnitTestCase {
   /**
    * Test builtin outputhandler creation
    */
-  public function testCreateBuiltin() {
+  public function testCreateBuiltin(): void {
     $form = new \CRM_Report_Form_SampleForm();
     $form->setOutputModeForTesting('csv');
     $outputHandler = OutputHandlerFactory::singleton()->create($form);
@@ -29,7 +29,7 @@ public function testCreateBuiltin() {
   /**
    * Test when no suitable handler available for given report parameters.
    */
-  public function testCreateNoMatch() {
+  public function testCreateNoMatch(): void {
     $form = new \CRM_Report_Form_SampleForm();
     $form->setOutputModeForTesting('something_nonexistent');
     $outputHandler = OutputHandlerFactory::singleton()->create($form);
@@ -39,7 +39,7 @@ public function testCreateNoMatch() {
   /**
    * Test handler made available via hook.
    */
-  public function testCreateWithHook() {
+  public function testCreateWithHook(): void {
     \Civi::dispatcher()->addListener('hook_civicrm_alterReportVar', [$this, 'hookForAlterReportVar']);
     $form = new \CRM_Report_Form_SampleForm();
     $form->setOutputModeForTesting('sample');
@@ -50,7 +50,7 @@ public function testCreateWithHook() {
   /**
    * Test actions modified by hook.
    */
-  public function testAlterReportVarHookWithActions() {
+  public function testAlterReportVarHookWithActions(): void {
     \Civi::dispatcher()->addListener('hook_civicrm_alterReportVar', [$this, 'hookForAlterReportVar']);
     $form = new \CRM_Report_Form_SampleForm();
     // NULL means no particular instance - running new report from template
diff --git a/tests/phpunit/Civi/Schema/MagicGetterSetterTest.php b/tests/phpunit/Civi/Schema/MagicGetterSetterTest.php
index 302a6598a5ca..8170ceb6ccdd 100644
--- a/tests/phpunit/Civi/Schema/MagicGetterSetterTest.php
+++ b/tests/phpunit/Civi/Schema/MagicGetterSetterTest.php
@@ -53,7 +53,7 @@ public function createEmptyExample() {
     };
   }
 
-  public function testExample() {
+  public function testExample(): void {
     $ex = $this->createExample();
     $this->assertEquals(NULL, $ex->setProtectedField(NULL)->getProtectedField());
     $this->assertEquals('apple', $ex->setProtectedField('apple')->getProtectedField());
@@ -107,7 +107,7 @@ public function testExample() {
     }
   }
 
-  public function testImplIndependence() {
+  public function testImplIndependence(): void {
     $ex1 = $this->createExample();
     $ex2 = $this->createAltExample();
     $ex3 = $this->createEmptyExample();
diff --git a/tests/phpunit/Civi/Test/ExampleSubscriberTest.php b/tests/phpunit/Civi/Test/ExampleSubscriberTest.php
index 3bc9c599f004..fac648ee6282 100644
--- a/tests/phpunit/Civi/Test/ExampleSubscriberTest.php
+++ b/tests/phpunit/Civi/Test/ExampleSubscriberTest.php
@@ -69,7 +69,7 @@ public function myAlterContentParams(&$content, $context, $tplName, &$object) {
     $content .= ' ' . __FUNCTION__;
   }
 
-  public function testPageOutput() {
+  public function testPageOutput(): void {
     ob_start();
     $p = new Main();
     $p->run();
@@ -78,7 +78,7 @@ public function testPageOutput() {
     $this->assertMatchesRegularExpression(';myAlterContentObject myAlterContentParams;', $content);
   }
 
-  public function testGetFields() {
+  public function testGetFields(): void {
     $this->assertEquals([], $this->tracker['civi.api.resolve']);
     $this->assertEquals([], $this->tracker['civi.api.prepare']);
     \civicrm_api3('Contact', 'getfields', []);
diff --git a/tests/phpunit/Civi/Test/InvasiveTest.php b/tests/phpunit/Civi/Test/InvasiveTest.php
index 7b109e383815..12f1af66a7d3 100644
--- a/tests/phpunit/Civi/Test/InvasiveTest.php
+++ b/tests/phpunit/Civi/Test/InvasiveTest.php
@@ -13,7 +13,7 @@
 
 class InvasiveTest extends \CiviUnitTestCase {
 
-  public function testPrivate() {
+  public function testPrivate(): void {
     $tgt = new InvasiveExample();
     $this->assertEquals(10, Invasive::get([$tgt, 'privateField']));
     $this->assertEquals(10, Invasive::call([$tgt, 'getPrivateField']));
@@ -25,7 +25,7 @@ public function testPrivate() {
     $this->assertEquals(1100, $theRef);
   }
 
-  public function testProtectedStatic() {
+  public function testProtectedStatic(): void {
     $tgt = InvasiveExample::class;
     $this->assertEquals(20, Invasive::get([$tgt, 'protectedStaticField']));
     $this->assertEquals(20, Invasive::call([$tgt, 'getProtectedStaticField']));
diff --git a/tests/phpunit/Civi/Token/TokenProcessorTest.php b/tests/phpunit/Civi/Token/TokenProcessorTest.php
index 16188e252989..f9c747ba6b0e 100644
--- a/tests/phpunit/Civi/Token/TokenProcessorTest.php
+++ b/tests/phpunit/Civi/Token/TokenProcessorTest.php
@@ -856,7 +856,7 @@ protected function getTokenProcessor(array $context = []): TokenProcessor {
   // *
   // * Ex: $tokenContext['oldSmartyVar'] = 'new_entity.new_field';
   // */
-  //  public function testSmartyTokenAlias_Contact() {
+  //  public function testSmartyTokenAlias_Contact(): void {
   //    $alice = $this->individualCreate(['first_name' => 'Alice']);
   //    $bob = $this->individualCreate(['first_name' => 'Bob']);
   //    $this->dispatcher->addSubscriber(new TokenCompatSubscriber());
diff --git a/tests/phpunit/Civi/WorkflowMessage/ExampleWorkflowMessageTest.php b/tests/phpunit/Civi/WorkflowMessage/ExampleWorkflowMessageTest.php
index a2616c1d66a2..fee20d887927 100644
--- a/tests/phpunit/Civi/WorkflowMessage/ExampleWorkflowMessageTest.php
+++ b/tests/phpunit/Civi/WorkflowMessage/ExampleWorkflowMessageTest.php
@@ -79,7 +79,7 @@ protected function exportExtraTplParams(array &$export): void {
     };
   }
 
-  public function testValidateFail() {
+  public function testValidateFail(): void {
     /** @var \Civi\WorkflowMessage\WorkflowMessageInterface $ex */
     $ex = static::createExample();
     $ex->import('modelProps', [
@@ -107,7 +107,7 @@ public function testValidateFail() {
     $this->assertEquals($expected, $errors);
   }
 
-  public function testValidatePass() {
+  public function testValidatePass(): void {
     /** @var \Civi\WorkflowMessage\WorkflowMessageInterface $ex */
     $ex = static::createExample();
     $ex->import('modelProps', [
@@ -125,7 +125,7 @@ public function testValidatePass() {
   /**
    * Assert that "getFields()" provides metadata from properties/docblocks.
    */
-  public function testGetFields() {
+  public function testGetFields(): void {
     /** @var \Civi\WorkflowMessage\WorkflowMessageInterface $ex */
     $ex = static::createExample();
     $fields = $ex->getFields();
@@ -155,7 +155,7 @@ public function testGetFields() {
   /**
    * Assert that getters/setters work on class fields.
    */
-  public function testGetSetClassFields() {
+  public function testGetSetClassFields(): void {
     /** @var \Civi\WorkflowMessage\WorkflowMessageInterface $ex */
     $ex = static::createExample();
 
@@ -171,7 +171,7 @@ public function testGetSetClassFields() {
   /**
    * Assert that import()/export() work on standard fields.
    */
-  public function testImportExportStandardField() {
+  public function testImportExportStandardField(): void {
     /** @var \Civi\WorkflowMessage\WorkflowMessageInterface $ex */
     $ex = static::createExample();
 
@@ -202,7 +202,7 @@ public function testImportExportStandardField() {
   /**
    * Assert that unrecognized fields are preserved in the round-trip from import=>export.
    */
-  public function testImportExportExtraField() {
+  public function testImportExportExtraField(): void {
     /** @var \Civi\WorkflowMessage\WorkflowMessageInterface $ex */
     $ex = static::createExample();
 
@@ -217,7 +217,7 @@ public function testImportExportExtraField() {
   /**
    * Assert that
    */
-  public function testImportExportUnmappedField() {
+  public function testImportExportUnmappedField(): void {
     /** @var \Civi\WorkflowMessage\WorkflowMessageInterface $ex */
     $ex = static::createExample();
 
@@ -265,7 +265,7 @@ public function testImpromptuImportExport(): void {
     $this->assertTrue(!isset($envelope['myProtectedInt']));
   }
 
-  public function testExampleRender() {
+  public function testExampleRender(): void {
     $hookCount = 0;
     $rand = rand(0, 1000);
     $cid = $this->individualCreate(['first_name' => 'Foo', 'last_name' => 'Bar' . $rand, 'prefix_id' => NULL, 'suffix_id' => NULL]);
@@ -285,7 +285,7 @@ public function testExampleRender() {
     $this->assertEquals('Hello Foo Bar' . $rand, $rendered['subject']);
   }
 
-  public function testImpromptuRender() {
+  public function testImpromptuRender(): void {
     $hookCount = 0;
     $rand = rand(0, 1000);
     $cid = $this->individualCreate(['first_name' => 'Foo', 'last_name' => 'Bar' . $rand, 'prefix_id' => NULL, 'suffix_id' => NULL]);
@@ -345,7 +345,7 @@ public function testRenderStoredTemplate(): void {
     $this->assertStringContainsString('Thank you for signing The Fake Petition', $rendered['text']);
   }
 
-  //public function testImpromptuTokens() {
+  //public function testImpromptuTokens(): void {
   //  /** @var \Civi\WorkflowMessage\GenericWorkflowMessage $ex */
   //  $ex = WorkflowMessage::create('some_impromptu_wf', [
   //    'envelope' => [
diff --git a/tests/phpunit/Civi/WorkflowMessage/Traits/AddressingTraitTest.php b/tests/phpunit/Civi/WorkflowMessage/Traits/AddressingTraitTest.php
index fa7ff283edcf..71c6817869f0 100644
--- a/tests/phpunit/Civi/WorkflowMessage/Traits/AddressingTraitTest.php
+++ b/tests/phpunit/Civi/WorkflowMessage/Traits/AddressingTraitTest.php
@@ -39,7 +39,7 @@ protected static function createExample() {
   /**
    * Set email addresses using fluent methods (setTo(), setCc(), etc).
    */
-  public function testFluentSetup() {
+  public function testFluentSetup(): void {
     $wfm = $this->createExample()
       // Setters support array or string inputs. All address fields support the same formats.
       ->setTo(['name' => 'Foo', 'email' => 'foo@example.com'])
@@ -59,7 +59,7 @@ public function testFluentSetup() {
   /**
    * Set email addresses using fluent methods (setTo(), setCc(), etc).
    */
-  public function testFluentAdder() {
+  public function testFluentAdder(): void {
     $wfm = $this->createExample()
       // Setters support array or string inputs. All address fields support the same formats.
       ->setCc([['email' => 'cc1@example.com'], ['name' => 'Bob', 'email' => 'cc2@example.com']])
@@ -72,7 +72,7 @@ public function testFluentAdder() {
   /**
    * Set email addresses using model-properties.
    */
-  public function testModelPropsSetup() {
+  public function testModelPropsSetup(): void {
     $wfm = $this->createExample()
       ->import('modelProps', [
         // modelProps support array or string inputs. All address fields support the same formats.
@@ -94,7 +94,7 @@ public function testModelPropsSetup() {
   /**
    * Set email addresses using sendTemplate()'s envelope format.
    */
-  public function testEnvelopeSetup() {
+  public function testEnvelopeSetup(): void {
     $ex = $this->createExample();
 
     $envelopeArray = [
@@ -121,7 +121,7 @@ public function testEnvelopeSetup() {
     }
   }
 
-  public function testSingularValues() {
+  public function testSingularValues(): void {
     $ex = $this->createExample();
 
     $singularFields = ['to', 'from', 'replyTo', 'cc', 'bcc'];
@@ -170,7 +170,7 @@ public function testSingularValues() {
     }
   }
 
-  public function testPluralValues() {
+  public function testPluralValues(): void {
     $ex = $this->createExample();
 
     $pluralFields = ['cc', 'bcc'];
diff --git a/tests/phpunit/CiviTest/CiviSimpleCacheTest.php b/tests/phpunit/CiviTest/CiviSimpleCacheTest.php
index a2967f854c8e..caac29302aac 100644
--- a/tests/phpunit/CiviTest/CiviSimpleCacheTest.php
+++ b/tests/phpunit/CiviTest/CiviSimpleCacheTest.php
@@ -170,7 +170,7 @@ public static function validData() {
     ];
   }
 
-  public function testSet() {
+  public function testSet(): void {
     if (isset($this->skippedTests[__FUNCTION__])) {
       $this->markTestSkipped($this->skippedTests[__FUNCTION__]);
     }
@@ -183,7 +183,7 @@ public function testSet() {
   /**
    * @medium
    */
-  public function testSetTtl() {
+  public function testSetTtl(): void {
     if (isset($this->skippedTests[__FUNCTION__])) {
       $this->markTestSkipped($this->skippedTests[__FUNCTION__]);
     }
@@ -201,7 +201,7 @@ public function testSetTtl() {
     $this->assertNull($this->cache->get('key2'), 'Value must expire after ttl.');
   }
 
-  public function testSetExpiredTtl() {
+  public function testSetExpiredTtl(): void {
     if (isset($this->skippedTests[__FUNCTION__])) {
       $this->markTestSkipped($this->skippedTests[__FUNCTION__]);
     }
@@ -216,7 +216,7 @@ public function testSetExpiredTtl() {
     $this->assertFalse($this->cache->has('key1'));
   }
 
-  public function testGet() {
+  public function testGet(): void {
     if (isset($this->skippedTests[__FUNCTION__])) {
       $this->markTestSkipped($this->skippedTests[__FUNCTION__]);
     }
@@ -228,7 +228,7 @@ public function testGet() {
     $this->assertEquals('value', $this->cache->get('key', 'foo'));
   }
 
-  public function testDelete() {
+  public function testDelete(): void {
     if (isset($this->skippedTests[__FUNCTION__])) {
       $this->markTestSkipped($this->skippedTests[__FUNCTION__]);
     }
@@ -239,7 +239,7 @@ public function testDelete() {
     $this->assertNull($this->cache->get('key'), 'Values must be deleted on delete()');
   }
 
-  public function testClear() {
+  public function testClear(): void {
     if (isset($this->skippedTests[__FUNCTION__])) {
       $this->markTestSkipped($this->skippedTests[__FUNCTION__]);
     }
@@ -250,7 +250,7 @@ public function testClear() {
     $this->assertNull($this->cache->get('key'), 'Values must be deleted on clear()');
   }
 
-  public function testSetMultiple() {
+  public function testSetMultiple(): void {
     if (isset($this->skippedTests[__FUNCTION__])) {
       $this->markTestSkipped($this->skippedTests[__FUNCTION__]);
     }
@@ -261,7 +261,7 @@ public function testSetMultiple() {
     $this->assertEquals('value1', $this->cache->get('key1'));
   }
 
-  public function testSetMultipleWithIntegerArrayKey() {
+  public function testSetMultipleWithIntegerArrayKey(): void {
     if (isset($this->skippedTests[__FUNCTION__])) {
       $this->markTestSkipped($this->skippedTests[__FUNCTION__]);
     }
@@ -274,7 +274,7 @@ public function testSetMultipleWithIntegerArrayKey() {
   /**
    * @medium
    */
-  public function testSetMultipleTtl() {
+  public function testSetMultipleTtl(): void {
     if (isset($this->skippedTests[__FUNCTION__])) {
       $this->markTestSkipped($this->skippedTests[__FUNCTION__]);
     }
@@ -292,7 +292,7 @@ public function testSetMultipleTtl() {
     $this->assertNull($this->cache->get('key4'), 'Value must expire after ttl.');
   }
 
-  public function testSetMultipleExpiredTtl() {
+  public function testSetMultipleExpiredTtl(): void {
     if (isset($this->skippedTests[__FUNCTION__])) {
       $this->markTestSkipped($this->skippedTests[__FUNCTION__]);
     }
@@ -302,7 +302,7 @@ public function testSetMultipleExpiredTtl() {
     $this->assertNull($this->cache->get('key1'));
   }
 
-  public function testSetMultipleWithGenerator() {
+  public function testSetMultipleWithGenerator(): void {
     if (isset($this->skippedTests[__FUNCTION__])) {
       $this->markTestSkipped($this->skippedTests[__FUNCTION__]);
     }
@@ -317,7 +317,7 @@ public function testSetMultipleWithGenerator() {
     $this->assertEquals('value1', $this->cache->get('key1'));
   }
 
-  public function testGetMultiple() {
+  public function testGetMultiple(): void {
     if (isset($this->skippedTests[__FUNCTION__])) {
       $this->markTestSkipped($this->skippedTests[__FUNCTION__]);
     }
@@ -347,7 +347,7 @@ public function testGetMultiple() {
     $this->assertSame(['key2', 'key3', 'key4'], $keys);
   }
 
-  public function testGetMultipleWithGenerator() {
+  public function testGetMultipleWithGenerator(): void {
     if (isset($this->skippedTests[__FUNCTION__])) {
       $this->markTestSkipped($this->skippedTests[__FUNCTION__]);
     }
@@ -378,7 +378,7 @@ public function testGetMultipleWithGenerator() {
     $this->assertNull($this->cache->get('key1'));
   }
 
-  public function testDeleteMultiple() {
+  public function testDeleteMultiple(): void {
     if (isset($this->skippedTests[__FUNCTION__])) {
       $this->markTestSkipped($this->skippedTests[__FUNCTION__]);
     }
@@ -393,7 +393,7 @@ public function testDeleteMultiple() {
     $this->assertNull($this->cache->get('key1'), 'Values must be deleted on deleteMultiple()');
   }
 
-  public function testDeleteMultipleGenerator() {
+  public function testDeleteMultipleGenerator(): void {
     if (isset($this->skippedTests[__FUNCTION__])) {
       $this->markTestSkipped($this->skippedTests[__FUNCTION__]);
     }
@@ -409,7 +409,7 @@ public function testDeleteMultipleGenerator() {
     $this->assertNull($this->cache->get('key1'), 'Values must be deleted on deleteMultiple()');
   }
 
-  public function testHas() {
+  public function testHas(): void {
     if (isset($this->skippedTests[__FUNCTION__])) {
       $this->markTestSkipped($this->skippedTests[__FUNCTION__]);
     }
@@ -419,7 +419,7 @@ public function testHas() {
     $this->assertTrue($this->cache->has('key0'));
   }
 
-  public function testBasicUsageWithLongKey() {
+  public function testBasicUsageWithLongKey(): void {
     if (isset($this->skippedTests[__FUNCTION__])) {
       $this->markTestSkipped($this->skippedTests[__FUNCTION__]);
     }
@@ -461,7 +461,7 @@ public function testGetMultipleInvalidKeys($key) {
     $result = $this->cache->getMultiple(['key1', $key, 'key2']);
   }
 
-  public function testGetMultipleNoIterable() {
+  public function testGetMultipleNoIterable(): void {
     if (isset($this->skippedTests[__FUNCTION__])) {
       $this->markTestSkipped($this->skippedTests[__FUNCTION__]);
     }
@@ -499,7 +499,7 @@ public function testSetMultipleInvalidKeys($key) {
     $this->cache->setMultiple($values());
   }
 
-  public function testSetMultipleNoIterable() {
+  public function testSetMultipleNoIterable(): void {
     if (isset($this->skippedTests[__FUNCTION__])) {
       $this->markTestSkipped($this->skippedTests[__FUNCTION__]);
     }
@@ -544,7 +544,7 @@ public function testDeleteMultipleInvalidKeys($key) {
     $this->cache->deleteMultiple(['key1', $key, 'key2']);
   }
 
-  public function testDeleteMultipleNoIterable() {
+  public function testDeleteMultipleNoIterable(): void {
     if (isset($this->skippedTests[__FUNCTION__])) {
       $this->markTestSkipped($this->skippedTests[__FUNCTION__]);
     }
@@ -577,7 +577,7 @@ public function testSetMultipleInvalidTtl($ttl) {
     $this->cache->setMultiple(['key' => 'value'], $ttl);
   }
 
-  public function testNullOverwrite() {
+  public function testNullOverwrite(): void {
     if (isset($this->skippedTests[__FUNCTION__])) {
       $this->markTestSkipped($this->skippedTests[__FUNCTION__]);
     }
@@ -588,7 +588,7 @@ public function testNullOverwrite() {
     $this->assertNull($this->cache->get('key'), 'Setting null to a key must overwrite previous value');
   }
 
-  public function testDataTypeString() {
+  public function testDataTypeString(): void {
     if (isset($this->skippedTests[__FUNCTION__])) {
       $this->markTestSkipped($this->skippedTests[__FUNCTION__]);
     }
@@ -599,7 +599,7 @@ public function testDataTypeString() {
     $this->assertTrue(is_string($result), 'Wrong data type. If we store a string we must get an string back.');
   }
 
-  public function testDataTypeInteger() {
+  public function testDataTypeInteger(): void {
     if (isset($this->skippedTests[__FUNCTION__])) {
       $this->markTestSkipped($this->skippedTests[__FUNCTION__]);
     }
@@ -610,7 +610,7 @@ public function testDataTypeInteger() {
     $this->assertTrue(is_int($result), 'Wrong data type. If we store an int we must get an int back.');
   }
 
-  public function testDataTypeFloat() {
+  public function testDataTypeFloat(): void {
     if (isset($this->skippedTests[__FUNCTION__])) {
       $this->markTestSkipped($this->skippedTests[__FUNCTION__]);
     }
@@ -622,7 +622,7 @@ public function testDataTypeFloat() {
     $this->assertEquals($float, $result);
   }
 
-  public function testDataTypeBoolean() {
+  public function testDataTypeBoolean(): void {
     if (isset($this->skippedTests[__FUNCTION__])) {
       $this->markTestSkipped($this->skippedTests[__FUNCTION__]);
     }
@@ -634,7 +634,7 @@ public function testDataTypeBoolean() {
     $this->assertTrue($this->cache->has('key'), 'has() should return true when true are stored. ');
   }
 
-  public function testDataTypeArray() {
+  public function testDataTypeArray(): void {
     if (isset($this->skippedTests[__FUNCTION__])) {
       $this->markTestSkipped($this->skippedTests[__FUNCTION__]);
     }
@@ -646,7 +646,7 @@ public function testDataTypeArray() {
     $this->assertEquals($array, $result);
   }
 
-  public function testDataTypeObject() {
+  public function testDataTypeObject(): void {
     if (isset($this->skippedTests[__FUNCTION__])) {
       $this->markTestSkipped($this->skippedTests[__FUNCTION__]);
     }
@@ -659,7 +659,7 @@ public function testDataTypeObject() {
     $this->assertEquals($object, $result);
   }
 
-  public function testBinaryData() {
+  public function testBinaryData(): void {
     if (isset($this->skippedTests[__FUNCTION__])) {
       $this->markTestSkipped($this->skippedTests[__FUNCTION__]);
     }
@@ -736,7 +736,7 @@ public function testSetMultipleValidData($data) {
     $this->assertSame(['key'], $keys);
   }
 
-  public function testObjectAsDefaultValue() {
+  public function testObjectAsDefaultValue(): void {
     if (isset($this->skippedTests[__FUNCTION__])) {
       $this->markTestSkipped($this->skippedTests[__FUNCTION__]);
     }
@@ -746,7 +746,7 @@ public function testObjectAsDefaultValue() {
     $this->assertEquals($obj, $this->cache->get('key', $obj));
   }
 
-  public function testObjectDoesNotChangeInCache() {
+  public function testObjectDoesNotChangeInCache(): void {
     if (isset($this->skippedTests[__FUNCTION__])) {
       $this->markTestSkipped($this->skippedTests[__FUNCTION__]);
     }
diff --git a/tests/phpunit/CiviTest/CiviTestSuite.php b/tests/phpunit/CiviTest/CiviTestSuite.php
index 854f650f93f1..7adc12620ab0 100644
--- a/tests/phpunit/CiviTest/CiviTestSuite.php
+++ b/tests/phpunit/CiviTest/CiviTestSuite.php
@@ -59,7 +59,7 @@ public function __construct($theClass = '', $name = '') {
    *  suppress failed test error issued by phpunit when it finds.
    *  a test suite with no tests
    */
-  public function testNothing() {
+  public function testNothing(): void {
   }
 
   /**
diff --git a/tests/phpunit/E2E/Api4/PermissionTest.php b/tests/phpunit/E2E/Api4/PermissionTest.php
index 9de532e000b4..17a4a66d9f9f 100644
--- a/tests/phpunit/E2E/Api4/PermissionTest.php
+++ b/tests/phpunit/E2E/Api4/PermissionTest.php
@@ -16,7 +16,7 @@ class PermissionTest extends \CiviEndToEndTestCase {
    *
    * This is a general sanity-check/well-formed-ness
    */
-  public function testGet() {
+  public function testGet(): void {
     // If the CMS integration is working,t hen you should expect one of these "smoke-test" permissions to be present.
     $smokeTest = [
       'Backdrop' => 'Drupal:post comments',
diff --git a/tests/phpunit/E2E/Cache/ArrayDecoratorTest.php b/tests/phpunit/E2E/Cache/ArrayDecoratorTest.php
index 2fcbd4102f37..9df2737523d7 100644
--- a/tests/phpunit/E2E/Cache/ArrayDecoratorTest.php
+++ b/tests/phpunit/E2E/Cache/ArrayDecoratorTest.php
@@ -30,7 +30,7 @@ public function createSimpleCache() {
     );
   }
 
-  public function testDoubleLifeWithDelete() {
+  public function testDoubleLifeWithDelete(): void {
     $this->assertFalse($this->a->has('foo'));
     $this->assertEquals('dfl-1', $this->a->get('foo', 'dfl-1'));
 
@@ -50,7 +50,7 @@ public function testDoubleLifeWithDelete() {
     $this->assertEquals('dfl-1', $this->a->get('foo', 'dfl-1'));
   }
 
-  public function testDoubleLifeWithClear() {
+  public function testDoubleLifeWithClear(): void {
     $this->assertFalse($this->a->has('foo'));
     $this->assertEquals('dfl-1', $this->a->get('foo', 'dfl-1'));
 
@@ -65,7 +65,7 @@ public function testDoubleLifeWithClear() {
     $this->assertEquals('dfl-1', $this->a->get('foo', 'dfl-1'));
   }
 
-  public function testSetTtl() {
+  public function testSetTtl(): void {
     // This test has exhibited some flakiness. It is overridden to
     // dump more detailed information about failures; however, it should be
     // substantively the same.
diff --git a/tests/phpunit/E2E/Cache/CacheTestCase.php b/tests/phpunit/E2E/Cache/CacheTestCase.php
index 2a4ce2f71647..d66f6b1501a0 100644
--- a/tests/phpunit/E2E/Cache/CacheTestCase.php
+++ b/tests/phpunit/E2E/Cache/CacheTestCase.php
@@ -29,7 +29,7 @@ public static function setUpBeforeClass(): void {
     parent::setUpBeforeClass();
   }
 
-  public function testBasicUsageWithLongKey() {
+  public function testBasicUsageWithLongKey(): void {
     if (isset($this->skippedTests[__FUNCTION__])) {
       $this->markTestSkipped($this->skippedTests[__FUNCTION__]);
     }
diff --git a/tests/phpunit/E2E/Cache/FastArrayDecoratorTest.php b/tests/phpunit/E2E/Cache/FastArrayDecoratorTest.php
index 3a244f3ee0b3..a1081de141d9 100644
--- a/tests/phpunit/E2E/Cache/FastArrayDecoratorTest.php
+++ b/tests/phpunit/E2E/Cache/FastArrayDecoratorTest.php
@@ -30,23 +30,23 @@ public function createSimpleCache() {
     );
   }
 
-  public function testSetTtl() {
+  public function testSetTtl(): void {
     $this->markTestSkipped('FastArrayDecorator breaks convention: Does not track TTL locally. However, TTL is passed along to delegate.');
   }
 
-  public function testSetMultipleTtl() {
+  public function testSetMultipleTtl(): void {
     $this->markTestSkipped('FastArrayDecorator breaks convention: Does not track TTL locally. However, TTL is passed along to delegate.');
   }
 
-  public function testDoubleLifeWithDelete() {
+  public function testDoubleLifeWithDelete(): void {
     $this->markTestSkipped('FastArrayDecorator breaks convention: Does not track TTL locally. However, TTL is passed along to delegate.');
   }
 
-  public function testDoubleLifeWithClear() {
+  public function testDoubleLifeWithClear(): void {
     $this->markTestSkipped('FastArrayDecorator breaks convention: Does not track TTL locally. However, TTL is passed along to delegate.');
   }
 
-  public function testObjectDoesNotChangeInCache() {
+  public function testObjectDoesNotChangeInCache(): void {
     $this->markTestSkipped('FastArrayDecorator breaks convention: No deep-copying cache content');
   }
 
diff --git a/tests/phpunit/E2E/Cache/TieredTest.php b/tests/phpunit/E2E/Cache/TieredTest.php
index bcff556417f1..3e08f89810b6 100644
--- a/tests/phpunit/E2E/Cache/TieredTest.php
+++ b/tests/phpunit/E2E/Cache/TieredTest.php
@@ -40,7 +40,7 @@ public function createSimpleCache($maxTimeouts = [86400]) {
     ], $maxTimeouts);
   }
 
-  public function testDoubleLifeWithDelete() {
+  public function testDoubleLifeWithDelete(): void {
     $this->assertFalse($this->a->has('foo'));
     $this->assertFalse($this->b->has('foo'));
     $this->assertEquals('dfl-1', $this->a->get('foo', 'dfl-1'));
@@ -70,7 +70,7 @@ public function testDoubleLifeWithDelete() {
     $this->assertEquals('dfl-2', $this->b->get('foo', 'dfl-2'));
   }
 
-  public function testDoubleLifeWithClear() {
+  public function testDoubleLifeWithClear(): void {
     $this->assertFalse($this->a->has('foo'));
     $this->assertFalse($this->b->has('foo'));
     $this->assertEquals('dfl-1', $this->a->get('foo', 'dfl-1'));
@@ -92,7 +92,7 @@ public function testDoubleLifeWithClear() {
     $this->assertEquals('dfl-2', $this->b->get('foo', 'dfl-2'));
   }
 
-  public function testTieredTimeout_default() {
+  public function testTieredTimeout_default(): void {
     $start = CRM_Utils_Time::getTimeRaw();
     $this->cache = $this->createSimpleCache([100, 1000]);
 
@@ -111,7 +111,7 @@ public function testTieredTimeout_default() {
     $this->assertApproxEquals($start + 1000, $this->b->getExpires('foo'), self::TOLERANCE);
   }
 
-  public function testTieredTimeout_explicitLow() {
+  public function testTieredTimeout_explicitLow(): void {
     $start = CRM_Utils_Time::getTimeRaw();
     $this->cache = $this->createSimpleCache([100, 1000]);
 
@@ -130,7 +130,7 @@ public function testTieredTimeout_explicitLow() {
     $this->assertApproxEquals($start + 50, $this->b->getExpires('foo'), self::TOLERANCE);
   }
 
-  public function testTieredTimeout_explicitMedium() {
+  public function testTieredTimeout_explicitMedium(): void {
     $start = CRM_Utils_Time::getTimeRaw();
     $this->cache = $this->createSimpleCache([100, 1000]);
 
@@ -149,7 +149,7 @@ public function testTieredTimeout_explicitMedium() {
     $this->assertApproxEquals($start + 500, $this->b->getExpires('foo'), self::TOLERANCE);
   }
 
-  public function testTieredTimeout_explicitHigh_lateReoad() {
+  public function testTieredTimeout_explicitHigh_lateReoad(): void {
     $start = CRM_Utils_Time::getTimeRaw();
     $this->cache = $this->createSimpleCache([100, 1000]);
 
diff --git a/tests/phpunit/E2E/Core/AssetBuilderTest.php b/tests/phpunit/E2E/Core/AssetBuilderTest.php
index d6f9b4b6e517..991329beec90 100644
--- a/tests/phpunit/E2E/Core/AssetBuilderTest.php
+++ b/tests/phpunit/E2E/Core/AssetBuilderTest.php
@@ -166,7 +166,7 @@ public function testGetUrl_uncached($asset, $params, $expectedMimeType, $expecte
     $this->assertEquals($expectedContent, $asset['content']);
   }
 
-  public function testInvalid() {
+  public function testInvalid(): void {
     \Civi::service('asset_builder')->setCacheEnabled(FALSE);
     $url = \Civi::service('asset_builder')->getUrl('invalid.json');
     try {
diff --git a/tests/phpunit/E2E/Core/HookTest.php b/tests/phpunit/E2E/Core/HookTest.php
index c159003c17a4..b7ff0be1f3bd 100644
--- a/tests/phpunit/E2E/Core/HookTest.php
+++ b/tests/phpunit/E2E/Core/HookTest.php
@@ -17,7 +17,7 @@ class HookTest extends \CiviEndToEndTestCase {
    *
    * This uses the canonical form, `CRM_Utils_Hook::invoke(string[] $names...)`
    */
-  public function testSymfonyListener_names() {
+  public function testSymfonyListener_names(): void {
     $calls = 0;
     $hookExample = function ($e) use (&$calls) {
       $calls++;
diff --git a/tests/phpunit/E2E/Core/LocalizedDataTest.php b/tests/phpunit/E2E/Core/LocalizedDataTest.php
index 14e01a714e11..cbe83863a6be 100644
--- a/tests/phpunit/E2E/Core/LocalizedDataTest.php
+++ b/tests/phpunit/E2E/Core/LocalizedDataTest.php
@@ -20,7 +20,7 @@ class LocalizedDataTest extends \CiviEndToEndTestCase {
    * $ env CIVICRM_LOCALES=en_US,fr_FR,de_DE ./bin/setup.sh -g \
    *   && phpunit6 tests/phpunit/E2E/Core/LocalizedDataTest.php
    */
-  public function testLocalizedData() {
+  public function testLocalizedData(): void {
     $getSql = $this->getSqlFunc();
 
     $sqls = [
diff --git a/tests/phpunit/E2E/Core/PathUrlTest.php b/tests/phpunit/E2E/Core/PathUrlTest.php
index 56d969e3ff76..e38486bb2821 100644
--- a/tests/phpunit/E2E/Core/PathUrlTest.php
+++ b/tests/phpunit/E2E/Core/PathUrlTest.php
@@ -16,7 +16,7 @@ class PathUrlTest extends \CiviEndToEndTestCase {
   /**
    * `CRM_Utils_System::url()` should generate working URLs.
    */
-  public function testSystemRouter() {
+  public function testSystemRouter(): void {
     $this->assertUrlContentRegex(';class="CRM_Mailing_Form_Subscribe";',
       \CRM_Utils_System::url('civicrm/mailing/subscribe', 'reset=1', TRUE, NULL, FALSE, TRUE));
   }
@@ -24,7 +24,7 @@ public function testSystemRouter() {
   /**
    * `Civi::paths()->getUrl()` should generate working URLs.
    */
-  public function testPaths_getUrl() {
+  public function testPaths_getUrl(): void {
     $p = \Civi::paths();
 
     $this->assertUrlContentRegex(';MIT-LICENSE.txt;',
@@ -38,7 +38,7 @@ public function testPaths_getUrl() {
   /**
    * `Civi::paths()->getPath()` should generate working paths.
    */
-  public function testPaths_getPath() {
+  public function testPaths_getPath(): void {
     $p = \Civi::paths();
 
     $this->assertFileContentRegex(';MIT-LICENSE.txt;',
@@ -52,7 +52,7 @@ public function testPaths_getPath() {
   /**
    * `Civi::paths()->getVariable()` should generate working paths+URLs.
    */
-  public function testPaths_getVariable() {
+  public function testPaths_getVariable(): void {
     $pathAndUrl = ['cms.root', 'civicrm.root', 'civicrm.packages', 'civicrm.files'];
     $pathOnly = ['civicrm.private', 'civicrm.log', 'civicrm.compile'];
     $urlOnly = [];
@@ -91,7 +91,7 @@ private function assertFileContentRegex($expectContentRegex, $file) {
   /**
    * @link https://lab.civicrm.org/dev/core/issues/1637
    */
-  public function testGetUrl_WpAdmin() {
+  public function testGetUrl_WpAdmin(): void {
     $config = \CRM_Core_Config::singleton();
     if ($config->userFramework !== 'WordPress') {
       $this->markTestSkipped('This test only applies to WP sites.');
diff --git a/tests/phpunit/E2E/Core/PrevNextTest.php b/tests/phpunit/E2E/Core/PrevNextTest.php
index 9fa33984b696..c1a5bd90aab9 100644
--- a/tests/phpunit/E2E/Core/PrevNextTest.php
+++ b/tests/phpunit/E2E/Core/PrevNextTest.php
@@ -45,7 +45,7 @@ protected function tearDown(): void {
     parent::tearDown();
   }
 
-  public function testFillSql() {
+  public function testFillSql(): void {
     $start = 0;
     $prefillLimit = 25;
     $sort = NULL;
@@ -72,7 +72,7 @@ public function testFillSql() {
     $this->assertSelections([]);
   }
 
-  public function testFillArray() {
+  public function testFillArray(): void {
     $rowSetA = [
       ['entity_id1' => 100, 'data' => 'Alice'],
       ['entity_id1' => 400, 'data' => 'Bob'],
@@ -100,7 +100,7 @@ public function testFillArray() {
     $this->assertSelections([], 'get', $this->cacheKey);
   }
 
-  public function testFetch() {
+  public function testFetch(): void {
     $this->testFillArray();
 
     $cids = $this->prevNext->fetch($this->cacheKey, 0, 2);
@@ -238,7 +238,7 @@ public function testGetPosition_invalid($fillFunction) {
     $this->assertTrue(!isset($pos['prev']));
   }
 
-  public function testDeleteByCacheKey() {
+  public function testDeleteByCacheKey(): void {
     // Add background data
     $this->prevNext->fillWithArray($this->cacheKeyB, [
       ['entity_id1' => 100, 'data' => 'Alice'],
@@ -266,7 +266,7 @@ public function testDeleteByCacheKey() {
     $this->assertSelections([100, 150], 'getall', $this->cacheKeyB);
   }
 
-  public function testDeleteByEntityId() {
+  public function testDeleteByEntityId(): void {
     // Fill two caches
     $this->prevNext->fillWithArray($this->cacheKey, [
       ['entity_id1' => 100, 'data' => 'Alice'],
@@ -292,7 +292,7 @@ public function testDeleteByEntityId() {
     $this->assertSelections([400], 'getall', $this->cacheKeyB);
   }
 
-  public function testDeleteAll() {
+  public function testDeleteAll(): void {
     // Fill two caches
     $this->prevNext->fillWithArray($this->cacheKey, [
       ['entity_id1' => 100, 'data' => 'Alice'],
diff --git a/tests/phpunit/E2E/Extern/BaseRestTest.php b/tests/phpunit/E2E/Extern/BaseRestTest.php
index 421fdaa5a29d..9d12ae31a43c 100644
--- a/tests/phpunit/E2E/Extern/BaseRestTest.php
+++ b/tests/phpunit/E2E/Extern/BaseRestTest.php
@@ -256,7 +256,7 @@ public function testAPICalls($query, $is_error) {
    * Submit a request with an API key that exists but does not correspond to.
    * a real user. Submit in "?entity=X&action=X" notation
    */
-  public function testNotCMSUser_entityAction() {
+  public function testNotCMSUser_entityAction(): void {
     $http = $this->createGuzzle(['http_errors' => FALSE]);
 
     //Create contact with api_key
@@ -289,7 +289,7 @@ public function testNotCMSUser_entityAction() {
    * Submit a request with an API key that exists but does not correspond to.
    * a real user. Submit in "?entity=X&action=X" notation
    */
-  public function testGetCorrectUserBack() {
+  public function testGetCorrectUserBack(): void {
     $this->updateAdminApiKey();
     $http = $this->createGuzzle(['http_errors' => FALSE]);
 
@@ -314,7 +314,7 @@ public function testGetCorrectUserBack() {
    * Submit a request with an API key that exists but does not correspond to
    * a real user. Submit in "?q=civicrm/$entity/$action" notation
    */
-  public function testNotCMSUser_q() {
+  public function testNotCMSUser_q(): void {
     if (!$this->isOldQSupported()) {
       $this->markTestSkipped('rest.php?q=civicrm/ENTITY/ACTION is not supported here');
     }
diff --git a/tests/phpunit/E2E/Extern/CliRunnerTest.php b/tests/phpunit/E2E/Extern/CliRunnerTest.php
index 89242d5a334b..e524ea2ea109 100644
--- a/tests/phpunit/E2E/Extern/CliRunnerTest.php
+++ b/tests/phpunit/E2E/Extern/CliRunnerTest.php
@@ -36,7 +36,7 @@ protected function setUp(): void {
   /**
    * Perform permission-checks using "on-behalf-of" mechanics.
    */
-  public function testPermissionLookup() {
+  public function testPermissionLookup(): void {
     $name = 'cv';
     $this->assertNotEmpty($this->findCommand($name), 'The command "$name" does not appear in the PATH.');
     $perms = ['administer CiviCRM', 'profile edit', 'sign CiviCRM Petition'];
diff --git a/tests/phpunit/E2E/Extern/WidgetTest.php b/tests/phpunit/E2E/Extern/WidgetTest.php
index 89f20c017402..4320e7942a70 100644
--- a/tests/phpunit/E2E/Extern/WidgetTest.php
+++ b/tests/phpunit/E2E/Extern/WidgetTest.php
@@ -25,7 +25,7 @@ class E2E_Extern_WidgetTest extends CiviEndToEndTestCase {
   /**
    * Return widget Javascript.
    */
-  public function testWidget() {
+  public function testWidget(): void {
     if (CIVICRM_UF !== 'Drupal8') {
       $endpoints['traditional'] = CRM_Core_Resources::singleton()->getUrl('civicrm', 'extern/widget.php');
     }
diff --git a/tests/phpunit/api/v3/APITest.php b/tests/phpunit/api/v3/APITest.php
index 8cbe3b767b2c..14538fc9754e 100644
--- a/tests/phpunit/api/v3/APITest.php
+++ b/tests/phpunit/api/v3/APITest.php
@@ -19,7 +19,7 @@ class api_v3_APITest extends CiviUnitTestCase {
 
   protected $_apiversion = 3;
 
-  public function testAPIReplaceVariables() {
+  public function testAPIReplaceVariables(): void {
     $result = [];
     $result['testfield'] = 6;
     $result['api.tag.get'] = 999;
@@ -52,7 +52,7 @@ public function testAPIReplaceVariables() {
   /**
    * Test that error doesn't occur for non-existent file.
    */
-  public function testAPIWrapperIncludeNoFile() {
+  public function testAPIWrapperIncludeNoFile(): void {
     $this->callAPIFailure(
       'RandomFile',
       'get',
@@ -61,18 +61,18 @@ public function testAPIWrapperIncludeNoFile() {
     );
   }
 
-  public function testAPIWrapperCamelCaseFunction() {
+  public function testAPIWrapperCamelCaseFunction(): void {
     $this->callAPISuccess('OptionGroup', 'Get', []);
   }
 
-  public function testAPIWrapperLcaseFunction() {
+  public function testAPIWrapperLcaseFunction(): void {
     $this->callAPISuccess('OptionGroup', 'get', []);
   }
 
   /**
    * Test resolver.
    */
-  public function testAPIResolver() {
+  public function testAPIResolver(): void {
     $oldPath = get_include_path();
     set_include_path($oldPath . PATH_SEPARATOR . dirname(__FILE__) . '/dataset/resolver');
 
@@ -86,7 +86,7 @@ public function testAPIResolver() {
     set_include_path($oldPath);
   }
 
-  public function testFromCamel() {
+  public function testFromCamel(): void {
     $cases = [
       'Contribution' => 'contribution',
       'contribution' => 'contribution',
@@ -103,7 +103,7 @@ public function testFromCamel() {
     }
   }
 
-  public function testToCamel() {
+  public function testToCamel(): void {
     $cases = [
       'Contribution' => 'Contribution',
       'contribution' => 'Contribution',
@@ -122,7 +122,7 @@ public function testToCamel() {
   /**
    * Test that calling via wrapper works.
    */
-  public function testv3Wrapper() {
+  public function testv3Wrapper(): void {
     try {
       $result = civicrm_api3('contact', 'get', []);
     }
@@ -136,7 +136,7 @@ public function testv3Wrapper() {
   /**
    * Test exception is thrown.
    */
-  public function testV3WrapperException() {
+  public function testV3WrapperException(): void {
     try {
       civicrm_api3('contact', 'create', ['debug' => 1]);
     }
@@ -153,7 +153,7 @@ public function testV3WrapperException() {
   /**
    * Test result parsing for null.
    */
-  public function testCreateNoStringNullResult() {
+  public function testCreateNoStringNullResult(): void {
     // create an example contact
     // $contact = CRM_Core_DAO::createTestObject('CRM_Contribute_DAO_ContributionPage')->toArray();
     $result = $this->callAPISuccess('ContributionPage', 'create', [
diff --git a/tests/phpunit/api/v3/APIWrapperTest.php b/tests/phpunit/api/v3/APIWrapperTest.php
index 770f6eba06ba..5fb69db9b28c 100644
--- a/tests/phpunit/api/v3/APIWrapperTest.php
+++ b/tests/phpunit/api/v3/APIWrapperTest.php
@@ -43,7 +43,7 @@ public function onApiWrappers(&$apiWrappers, $apiRequest) {
     $apiWrappers[] = new api_v3_APIWrapperTest_Impl();
   }
 
-  public function testWrapperHook() {
+  public function testWrapperHook(): void {
     // Note: this API call would fail due to missing contact_type, but
     // the wrapper intervenes (fromApiInput)
     // Note: The output would define "display_name", but the wrapper
diff --git a/tests/phpunit/api/v3/ActivityCaseTest.php b/tests/phpunit/api/v3/ActivityCaseTest.php
index 9c40aa54fb48..8690af852850 100644
--- a/tests/phpunit/api/v3/ActivityCaseTest.php
+++ b/tests/phpunit/api/v3/ActivityCaseTest.php
@@ -53,7 +53,7 @@ public function setUp(): void {
    * Test activity creation on case based
    * on id or hash present in case subject.
    */
-  public function testActivityCreateOnCase() {
+  public function testActivityCreateOnCase(): void {
     $hash = substr(sha1(CIVICRM_SITE_KEY . $this->_case['id']), 0, 7);
     $subjectArr = [
       "[case #{$this->_case['id']}] test activity recording under case with id",
@@ -74,7 +74,7 @@ public function testActivityCreateOnCase() {
   /**
    * Same as testActivityCreateOnCase but editing an existing non-case activity
    */
-  public function testActivityEditAddingCaseIdInSubject() {
+  public function testActivityEditAddingCaseIdInSubject(): void {
     $activity = $this->callAPISuccess('Activity', 'create', [
       'source_contact_id' => $this->_cid,
       'activity_type_id' => 'Meeting',
@@ -104,7 +104,7 @@ public function testActivityEditAddingCaseIdInSubject() {
     $this->assertEquals($this->_case['id'], $case['case_id'][0]);
   }
 
-  public function testGet() {
+  public function testGet(): void {
     $this->assertTrue(is_numeric($this->_case['id']));
     $this->assertTrue(is_numeric($this->_otherActivity['id']));
 
@@ -132,7 +132,7 @@ public function testGet() {
     $this->assertEquals([], array_intersect($getByCaseId_ids, $getByCaseNull_ids));
   }
 
-  public function testActivityGetWithCaseInfo() {
+  public function testActivityGetWithCaseInfo(): void {
     $activities = $this->callAPISuccess('Activity', 'get', [
       'sequential' => 1,
       'case_id' => $this->_case['id'],
diff --git a/tests/phpunit/api/v3/ActivityContactTest.php b/tests/phpunit/api/v3/ActivityContactTest.php
index b1a1b10f6181..a848a6896cd7 100644
--- a/tests/phpunit/api/v3/ActivityContactTest.php
+++ b/tests/phpunit/api/v3/ActivityContactTest.php
@@ -115,7 +115,7 @@ public function testGetEmptyParams($version) {
    * Test civicrm_activity_contact_get with wrong params.
    * FIXME: Api4
    */
-  public function testGetWrongParams() {
+  public function testGetWrongParams(): void {
     $this->callAPIFailure('ActivityContact', 'Get', ['contact_id' => 'abc']);
     $this->callAPIFailure('ActivityContact', 'Get', ['activity_id' => 'abc']);
     $this->callAPIFailure('ActivityContact', 'Get', ['record_type_id' => 'abc']);
diff --git a/tests/phpunit/api/v3/ActivityTest.php b/tests/phpunit/api/v3/ActivityTest.php
index 82a0d7d11877..3de379cc7bf0 100644
--- a/tests/phpunit/api/v3/ActivityTest.php
+++ b/tests/phpunit/api/v3/ActivityTest.php
@@ -145,7 +145,7 @@ public function testActivityCreateWithoutRequired($version) {
    * Test civicrm_activity_create() with mismatched activity_type_id
    * and activity_name.
    */
-  public function testActivityCreateMismatchNameType() {
+  public function testActivityCreateMismatchNameType(): void {
     $params = [
       'source_contact_id' => $this->_contactID,
       'subject' => 'Test activity',
@@ -165,7 +165,7 @@ public function testActivityCreateMismatchNameType() {
   /**
    * Test civicrm_activity_id() with missing source_contact_id is put with the current user.
    */
-  public function testActivityCreateWithMissingContactId() {
+  public function testActivityCreateWithMissingContactId(): void {
     $params = [
       'subject' => 'Make-it-Happen Meeting',
       'activity_date_time' => date('Ymd'),
@@ -184,7 +184,7 @@ public function testActivityCreateWithMissingContactId() {
    *
    * Since the field is required the validation should reject the default.
    */
-  public function testActivityCreateWithMissingContactIdNoLoggedInUser() {
+  public function testActivityCreateWithMissingContactIdNoLoggedInUser(): void {
     CRM_Core_Session::singleton()->set('userID', NULL);
     $params = [
       'subject' => 'Make-it-Happen Meeting',
@@ -226,7 +226,7 @@ public function testActivityCreateWithNonNumericContactId($version) {
    * Oddly enough this test was failing because the creation of the invalid type
    * got added to the set up routine. Probably a mis-fix on a test
    */
-  public function testActivityCreateWithNonNumericActivityTypeId() {
+  public function testActivityCreateWithNonNumericActivityTypeId(): void {
     $params = [
       'source_contact_id' => $this->_contactID,
       'subject' => 'Make-it-Happen Meeting',
@@ -244,7 +244,7 @@ public function testActivityCreateWithNonNumericActivityTypeId() {
   /**
    * Check with incorrect required fields.
    */
-  public function testActivityCreateWithUnknownActivityTypeId() {
+  public function testActivityCreateWithUnknownActivityTypeId(): void {
     $this->callAPIFailure('activity', 'create', [
       'source_contact_id' => $this->_contactID,
       'subject' => 'Make-it-Happen Meeting',
@@ -257,7 +257,7 @@ public function testActivityCreateWithUnknownActivityTypeId() {
     ]);
   }
 
-  public function testActivityCreateWithInvalidPriority() {
+  public function testActivityCreateWithInvalidPriority(): void {
     $params = [
       'source_contact_id' => $this->_contactID,
       'subject' => 'Make-it-Happen Meeting',
@@ -278,7 +278,7 @@ public function testActivityCreateWithInvalidPriority() {
   /**
    * Test create succeeds with valid string for priority.
    */
-  public function testActivityCreateWithValidStringPriority() {
+  public function testActivityCreateWithValidStringPriority(): void {
     $params = [
       'source_contact_id' => $this->_contactID,
       'subject' => 'Make-it-Happen Meeting',
@@ -298,7 +298,7 @@ public function testActivityCreateWithValidStringPriority() {
   /**
    * Test create fails with invalid priority string.
    */
-  public function testActivityCreateWithInValidStringPriority() {
+  public function testActivityCreateWithInValidStringPriority(): void {
     $params = [
       'source_contact_id' => $this->_contactID,
       'subject' => 'Make-it-Happen Meeting',
@@ -415,7 +415,7 @@ public function testActivityReturnTargetAssignee(int $version): void {
   /**
    * Test get returns target and assignee contact names.
    */
-  public function testActivityReturnTargetAssigneeName() {
+  public function testActivityReturnTargetAssigneeName(): void {
 
     $target1 = $this->callAPISuccess('Contact', 'create', ['contact_type' => 'Individual', 'first_name' => 'A', 'last_name' => 'Cat']);
     $target2 = $this->callAPISuccess('Contact', 'create', ['contact_type' => 'Individual', 'first_name' => 'B', 'last_name' => 'Good']);
@@ -450,7 +450,7 @@ public function testActivityReturnTargetAssigneeName() {
   /**
    * Test civicrm_activity_create() with valid parameters and custom data.
    */
-  public function testActivityCreateCustom() {
+  public function testActivityCreateCustom(): void {
     $ids = $this->entityCustomGroupWithSingleFieldCreate(__FUNCTION__, __FILE__);
     $params = $this->_params;
     $params['custom_' . $ids['custom_field_id']] = "custom string";
@@ -468,7 +468,7 @@ public function testActivityCreateCustom() {
   /**
    * Test civicrm_activity_create() with valid parameters and custom data.
    */
-  public function testActivityCreateCustomSubType() {
+  public function testActivityCreateCustomSubType(): void {
     $ids = $this->entityCustomGroupWithSingleFieldCreate(__FUNCTION__, __FILE__);
     $this->callAPISuccess('CustomGroup', 'create', [
       'extends_entity_column_value' => $this->test_activity_type_value,
@@ -492,7 +492,7 @@ public function testActivityCreateCustomSubType() {
   /**
    * Test civicrm_activity_create() with valid parameters and custom data.
    */
-  public function testActivityCreateCustomContactRefField() {
+  public function testActivityCreateCustomContactRefField(): void {
 
     $this->callAPISuccess('contact', 'create', ['id' => $this->_contactID, 'sort_name' => 'Contact, Test']);
     $ids = $this->entityCustomGroupWithSingleFieldCreate(__FUNCTION__, __FILE__);
@@ -528,7 +528,7 @@ public function testActivityCreateCustomContactRefField() {
   /**
    * Test civicrm_activity_create() with an invalid text status_id.
    */
-  public function testActivityCreateBadTextStatus() {
+  public function testActivityCreateBadTextStatus(): void {
 
     $params = [
       'source_contact_id' => $this->_contactID,
@@ -547,7 +547,7 @@ public function testActivityCreateBadTextStatus() {
   /**
    * Test civicrm_activity_create() with an invalid text status_id.
    */
-  public function testActivityCreateSupportActivityStatus() {
+  public function testActivityCreateSupportActivityStatus(): void {
 
     $params = [
       'source_contact_id' => $this->_contactID,
@@ -567,7 +567,7 @@ public function testActivityCreateSupportActivityStatus() {
   /**
    * Test civicrm_activity_create() with using a text status_id.
    */
-  public function testActivityCreateTextStatus() {
+  public function testActivityCreateTextStatus(): void {
 
     $params = [
       'source_contact_id' => $this->_contactID,
@@ -591,14 +591,14 @@ public function testActivityCreateTextStatus() {
   /**
    * Test civicrm_activity_get() with no params
    */
-  public function testActivityGetEmpty() {
+  public function testActivityGetEmpty(): void {
     $this->callAPISuccess('activity', 'get', []);
   }
 
   /**
    * Test civicrm_activity_get() with a good activity ID
    */
-  public function testActivityGetGoodID1() {
+  public function testActivityGetGoodID1(): void {
     // Insert rows in civicrm_activity creating activities 4 and 13
     $activity = $this->callAPISuccess('activity', 'create', $this->_params);
 
@@ -638,7 +638,7 @@ public function testActivityGetGoodID1() {
   /**
    * test that get functioning does filtering.
    */
-  public function testGetFilter() {
+  public function testGetFilter(): void {
     $params = [
       'source_contact_id' => $this->_contactID,
       'subject' => 'Make-it-Happen Meeting',
@@ -660,7 +660,7 @@ public function testGetFilter() {
   /**
    * Test civicrm_activity_get() with filter target_contact_id
    */
-  public function testActivityGetTargetFilter() {
+  public function testActivityGetTargetFilter(): void {
     $params = $this->_params;
     $contact1Params = [
       'first_name' => 'John',
@@ -712,7 +712,7 @@ public function testActivityGetTargetFilter() {
   /**
    * Test that activity.get api works when filtering on subject.
    */
-  public function testActivityGetSubjectFilter() {
+  public function testActivityGetSubjectFilter(): void {
     $subject = 'test activity ' . __FUNCTION__ . mt_rand();
     $params = $this->_params;
     $params['subject'] = $subject;
@@ -725,7 +725,7 @@ public function testActivityGetSubjectFilter() {
   /**
    * Test that activity.get api works when filtering on details.
    */
-  public function testActivityGetDetailsFilter() {
+  public function testActivityGetDetailsFilter(): void {
     $details = 'test activity ' . __FUNCTION__ . mt_rand();
     $params = $this->_params;
     $params['details'] = $details;
@@ -738,7 +738,7 @@ public function testActivityGetDetailsFilter() {
   /**
    * Test that activity.get api works when filtering on tag.
    */
-  public function testActivityGetTagFilter() {
+  public function testActivityGetTagFilter(): void {
     $tag = $this->callAPISuccess('Tag', 'create', ['name' => mt_rand(), 'used_for' => 'Activities']);
     $activity = $this->callAPISuccess('Activity', 'Create', $this->_params);
     $this->callAPISuccess('EntityTag', 'create', ['entity_table' => 'civicrm_activity', 'tag_id' => $tag['id'], 'entity_id' => $activity['id']]);
@@ -751,7 +751,7 @@ public function testActivityGetTagFilter() {
   /**
    * Return tag info
    */
-  public function testJoinOnTags() {
+  public function testJoinOnTags(): void {
     $tagName = 'act_tag_nm_' . mt_rand();
     $tagDescription = 'act_tag_ds_' . mt_rand();
     $tagColor = '#' . substr(md5(mt_rand()), 0, 6);
@@ -770,7 +770,7 @@ public function testJoinOnTags() {
   /**
    * Test that activity.get api works to filter on and return files.
    */
-  public function testActivityGetFile() {
+  public function testActivityGetFile(): void {
     $activity = $this->callAPISuccess('Activity', 'create', $this->_params);
     $activity2 = $this->callAPISuccess('Activity', 'create', $this->_params2);
     $file = $this->callAPISuccess('Attachment', 'create', [
@@ -792,7 +792,7 @@ public function testActivityGetFile() {
   /**
    * test that get functioning does filtering.
    */
-  public function testGetStatusID() {
+  public function testGetStatusID(): void {
     $params = [
       'source_contact_id' => $this->_contactID,
       'subject' => 'Make-it-Happen Meeting',
@@ -873,7 +873,7 @@ public function testGetFilterMaxDate(): void {
    * Test civicrm_activity_get() with a good activity ID which
    * has associated custom data
    */
-  public function testActivityGetGoodIDCustom() {
+  public function testActivityGetGoodIDCustom(): void {
     $ids = $this->entityCustomGroupWithSingleFieldCreate(__FUNCTION__, __FILE__);
 
     $params = $this->_params;
@@ -951,7 +951,7 @@ public function testActivityUpdateWithoutRequired(): void {
   /**
    * Test civicrm_activity_update() with non-numeric id
    */
-  public function testActivityUpdateWithNonNumericId() {
+  public function testActivityUpdateWithNonNumericId(): void {
     $params = [
       'id' => 'lets break it',
       'activity_name' => 'Meeting',
@@ -965,7 +965,7 @@ public function testActivityUpdateWithNonNumericId() {
   /**
    * Check with incorrect required fields.
    */
-  public function testActivityUpdateWithIncorrectContactActivityType() {
+  public function testActivityUpdateWithIncorrectContactActivityType(): void {
     $params = [
       'id' => 1,
       'activity_name' => 'Test Activity',
@@ -1105,7 +1105,7 @@ public function testActivityUpdateCustom(): void {
    * Test civicrm_activity_update() for core activity fields
    * and some custom data
    */
-  public function testActivityUpdateCheckCoreFields() {
+  public function testActivityUpdateCheckCoreFields(): void {
     $params = $this->_params;
     $contact1Params = [
       'first_name' => 'John',
@@ -1208,7 +1208,7 @@ public function testActivityUpdateCheckCoreFields() {
    * Test civicrm_activity_update() where the DB has a date_time
    * value and there is none in the update params.
    */
-  public function testActivityUpdateNotDate() {
+  public function testActivityUpdateNotDate(): void {
     $result = $this->callAPISuccess('activity', 'create', $this->_params);
 
     $params = [
@@ -1233,7 +1233,7 @@ public function testActivityUpdateNotDate() {
   /**
    * Check activity update with status.
    */
-  public function testActivityUpdateWithStatus() {
+  public function testActivityUpdateWithStatus(): void {
     $activity = $this->callAPISuccess('activity', 'create', $this->_params);
     $params = [
       'id' => $activity['id'],
@@ -1303,7 +1303,7 @@ public function testChainedActivityGet(): void {
   /**
    * Test civicrm_activity_contact_get() with invalid Contact ID.
    */
-  public function testActivitiesContactGetWithInvalidContactId() {
+  public function testActivitiesContactGetWithInvalidContactId(): void {
     $params = ['contact_id' => 'contact'];
     $this->callAPIFailure('activity', 'get', $params);
   }
@@ -1311,7 +1311,7 @@ public function testActivitiesContactGetWithInvalidContactId() {
   /**
    * Test civicrm_activity_contact_get() with contact having no Activity.
    */
-  public function testActivitiesContactGetHavingNoActivity() {
+  public function testActivitiesContactGetHavingNoActivity(): void {
     $params = [
       'first_name' => 'dan',
       'last_name' => 'conberg',
@@ -1330,7 +1330,7 @@ public function testActivitiesContactGetHavingNoActivity() {
   /**
    * Test getfields function.
    */
-  public function testGetFields() {
+  public function testGetFields(): void {
     $params = ['action' => 'create'];
     $result = $this->callAPISuccess('activity', 'getfields', $params);
     $this->assertTrue(is_array($result['values']), 'get fields doesn\'t return values array');
@@ -1342,7 +1342,7 @@ public function testGetFields() {
   /**
    * Test or operator in api params
    */
-  public function testGetWithOr() {
+  public function testGetWithOr(): void {
     $acts = [
       'test or 1' => 'orOperator',
       'test or 2' => 'orOperator',
@@ -1374,7 +1374,7 @@ public function testGetWithOr() {
   /**
    * Test handling of is_overdue calculated field
    */
-  public function testGetOverdue() {
+  public function testGetOverdue(): void {
     $overdueAct = $this->callAPISuccess('Activity', 'create', [
       'activity_date_time' => 'now - 1 week',
       'status_id' => 'Scheduled',
diff --git a/tests/phpunit/api/v3/ActivityTypeTest.php b/tests/phpunit/api/v3/ActivityTypeTest.php
index 7552969f2c1a..a33739d232fa 100644
--- a/tests/phpunit/api/v3/ActivityTypeTest.php
+++ b/tests/phpunit/api/v3/ActivityTypeTest.php
@@ -44,7 +44,7 @@ public function setUp(): void {
   /**
    * Test civicrm_activity_type_get().
    */
-  public function testActivityTypeGet() {
+  public function testActivityTypeGet(): void {
     $params = [];
     $result = $this->callAPISuccess('activity_type', 'get', $params);
     $this->assertEquals($result['values']['1'], 'Meeting');
@@ -53,7 +53,7 @@ public function testActivityTypeGet() {
   /**
    * Test civicrm_activity_type_create().
    */
-  public function testActivityTypeCreate() {
+  public function testActivityTypeCreate(): void {
     $params = [
       'weight' => '2',
       'label' => 'send out letters',
@@ -68,7 +68,7 @@ public function testActivityTypeCreate() {
   /**
    * Test civicrm_activity_type_create - check id
    */
-  public function testActivityTypecreatecheckId() {
+  public function testActivityTypecreatecheckId(): void {
     $params = [
       'label' => 'type_create',
       'weight' => '2',
@@ -81,7 +81,7 @@ public function testActivityTypecreatecheckId() {
   /**
    * Test civicrm_activity_type_delete()
    */
-  public function testActivityTypeDelete() {
+  public function testActivityTypeDelete(): void {
     $params = [
       'label' => 'type_create_delete',
       'weight' => '2',
diff --git a/tests/phpunit/api/v3/AddressTest.php b/tests/phpunit/api/v3/AddressTest.php
index 24adbdbc41b1..766dbe5cc16f 100644
--- a/tests/phpunit/api/v3/AddressTest.php
+++ b/tests/phpunit/api/v3/AddressTest.php
@@ -125,7 +125,7 @@ public function testCreateAddressDefaultLocation($version) {
   /**
    * FIXME: Api4
    */
-  public function testCreateAddressTooLongSuffix() {
+  public function testCreateAddressTooLongSuffix(): void {
     $params = $this->_params;
     $params['street_number_suffix'] = 'really long string';
     $this->callAPIFailure('address', 'create', $params);
@@ -432,7 +432,7 @@ public function testCreateAddressPrimaryHandlingChangeExisting($version) {
    * @link https://chat.civicrm.org/civicrm/pl/zcq3jkg69jdt5g4aqze6bbe9pc
    * FIXME: Api4
    */
-  public function testCreateDuplicateLocationTypes() {
+  public function testCreateDuplicateLocationTypes(): void {
     $address1 = $this->callAPISuccess('address', 'create', $this->_params);
     $address2 = $this->callAPISuccess('address', 'create', [
       'location_type_id' => $this->_locationTypeID,
@@ -451,7 +451,7 @@ public function testCreateDuplicateLocationTypes() {
     $this->callAPISuccess('address', 'delete', ['id' => $address2['id']]);
   }
 
-  public function testGetWithJoin() {
+  public function testGetWithJoin(): void {
     $cid = $this->individualCreate([
       'api.Address.create' => [
         'street_address' => __FUNCTION__,
@@ -472,7 +472,7 @@ public function testGetWithJoin() {
    *
    * @see https://lab.civicrm.org/dev/core/issues/725
    */
-  public function testCreateAddressStateProvinceIDCorrectForCountry() {
+  public function testCreateAddressStateProvinceIDCorrectForCountry(): void {
     $params = $this->_params;
     $params['sequential'] = 1;
     // United States country id
@@ -578,7 +578,7 @@ public function testBuildCountryWithDodgyCountryLimitSetting($version) {
     $this->callAPISuccess('address', 'getoptions', ['field' => 'country_id']);
   }
 
-  public function testBuildCountyWithDodgeStateProvinceFiltering() {
+  public function testBuildCountyWithDodgeStateProvinceFiltering(): void {
     $result = $this->callAPIFailure('Address', 'getoptions', [
       'field' => 'county_id',
       'state_province_id' => "abcd;ef",
@@ -591,7 +591,7 @@ public function testBuildCountyWithDodgeStateProvinceFiltering() {
     $this->assertEquals('San Francisco', $goodResult['values'][4]);
   }
 
-  public function testGetOptionsAbbr() {
+  public function testGetOptionsAbbr(): void {
     $result = $this->callAPISuccess('Address', 'getoptions', [
       'field' => 'country_id',
       'context' => 'abbreviate',
diff --git a/tests/phpunit/api/v3/AttachmentTest.php b/tests/phpunit/api/v3/AttachmentTest.php
index 05370070473f..2913e91f5f80 100644
--- a/tests/phpunit/api/v3/AttachmentTest.php
+++ b/tests/phpunit/api/v3/AttachmentTest.php
@@ -449,7 +449,7 @@ public function testCreateShouldSetCreatedIdAsTheLoggedInUser(): void {
     $this->assertEquals($loggedInUser, $createResult['values'][$fileId]['created_id']);
   }
 
-  public function testCreateShouldKeepCreatedIdEmptyIfTheresNoLoggedInUser() {
+  public function testCreateShouldKeepCreatedIdEmptyIfTheresNoLoggedInUser(): void {
     $testEntityClass = 'CRM_Activity_DAO_Activity';
     $entity = CRM_Core_DAO::createTestObject($testEntityClass);
     $entity_table = CRM_Core_DAO_AllCoreTables::getTableForClass($testEntityClass);
@@ -467,7 +467,7 @@ public function testCreateShouldKeepCreatedIdEmptyIfTheresNoLoggedInUser() {
     $this->assertEmpty($createResult['values'][$fileId]['created_id']);
   }
 
-  public function testCreateShouldNotUpdateTheCreatedId() {
+  public function testCreateShouldNotUpdateTheCreatedId(): void {
     $testEntityClass = 'CRM_Activity_DAO_Activity';
     $entity = CRM_Core_DAO::createTestObject($testEntityClass);
     $entity_table = CRM_Core_DAO_AllCoreTables::getTableForClass($testEntityClass);
diff --git a/tests/phpunit/api/v3/CRM11793Test.php b/tests/phpunit/api/v3/CRM11793Test.php
index e1a5a5b6ebd9..de4b6f1bd39c 100644
--- a/tests/phpunit/api/v3/CRM11793Test.php
+++ b/tests/phpunit/api/v3/CRM11793Test.php
@@ -36,15 +36,15 @@ public function tearDown(): void {
    * Verify that attempt to create individual contact with only
    * first and last names succeeds
    */
-  public function testCRM11793Organization() {
+  public function testCRM11793Organization(): void {
     $this->_testCRM11793ContactType('Organization');
   }
 
-  public function testCRM11793Household() {
+  public function testCRM11793Household(): void {
     $this->_testCRM11793ContactType('Household');
   }
 
-  public function testCRM11793Individual() {
+  public function testCRM11793Individual(): void {
     $this->_testCRM11793ContactType('Individual');
   }
 
diff --git a/tests/phpunit/api/v3/CaseContactTest.php b/tests/phpunit/api/v3/CaseContactTest.php
index 2a0fdb9d9f08..d442facbd1a1 100644
--- a/tests/phpunit/api/v3/CaseContactTest.php
+++ b/tests/phpunit/api/v3/CaseContactTest.php
@@ -48,7 +48,7 @@ public function setUp(): void {
     ];
   }
 
-  public function testCaseContactGet() {
+  public function testCaseContactGet(): void {
     $result = $this->callAPISuccess('CaseContact', 'get', [
       'contact_id' => $this->contactID,
     ]);
@@ -58,7 +58,7 @@ public function testCaseContactGet() {
   /**
    * Test create function with valid parameters.
    */
-  public function testCaseContactCreate() {
+  public function testCaseContactCreate(): void {
     $params = $this->params;
     $result = $this->callAPISuccess('CaseContact', 'create', $params);
     $id = $result['id'];
diff --git a/tests/phpunit/api/v3/CaseTest.php b/tests/phpunit/api/v3/CaseTest.php
index 9da8b6ac854f..b6477b53f5bb 100644
--- a/tests/phpunit/api/v3/CaseTest.php
+++ b/tests/phpunit/api/v3/CaseTest.php
@@ -88,14 +88,14 @@ public function tearDown(): void {
   /**
    * Check with empty array.
    */
-  public function testCaseCreateEmpty() {
+  public function testCaseCreateEmpty(): void {
     $this->callAPIFailure('case', 'create', []);
   }
 
   /**
    * Check if required fields are not passed.
    */
-  public function testCaseCreateWithoutRequired() {
+  public function testCaseCreateWithoutRequired(): void {
     $params = [
       'subject' => 'this case should fail',
       'case_type_id' => 1,
@@ -107,7 +107,7 @@ public function testCaseCreateWithoutRequired() {
   /**
    * Test Getlist with id and case_id
    */
-  public function testCaseGetListById() {
+  public function testCaseGetListById(): void {
     $params = $this->_params;
     $params['contact_id'] = $this->individualCreate();
 
@@ -158,7 +158,7 @@ public function testCaseGetListById() {
   /**
    * Test create function with valid parameters.
    */
-  public function testCaseCreate() {
+  public function testCaseCreate(): void {
     $params = $this->_params;
     // Test using name instead of value.
     unset($params['case_type_id']);
@@ -176,7 +176,7 @@ public function testCaseCreate() {
   /**
    * Test create function with resolved status.
    */
-  public function testCaseCreateWithResolvedStatus() {
+  public function testCaseCreateWithResolvedStatus(): void {
     $params = $this->_params;
     // Test using name instead of value.
     unset($params['case_type_id']);
@@ -213,7 +213,7 @@ public function testCaseCreateWithResolvedStatus() {
   /**
    * Test case create with valid parameters and custom data.
    */
-  public function testCaseCreateCustom() {
+  public function testCaseCreateCustom(): void {
     $ids = $this->entityCustomGroupWithSingleFieldCreate(__FUNCTION__, __FILE__);
     $params = $this->_params;
     $params['custom_' . $ids['custom_field_id']] = "custom string";
@@ -231,7 +231,7 @@ public function testCaseCreateCustom() {
   /**
    * Test update (create with id) function with valid parameters.
    */
-  public function testCaseUpdate() {
+  public function testCaseUpdate(): void {
     $params = $this->_params;
     // Test using name instead of value
     unset($params['case_type_id']);
@@ -257,7 +257,7 @@ public function testCaseUpdate() {
   /**
    * Test update (create with id) function with valid parameters.
    */
-  public function testCaseUpdateWithExistingCaseContact() {
+  public function testCaseUpdateWithExistingCaseContact(): void {
     $params = $this->_params;
     // Test using name instead of value
     unset($params['case_type_id']);
@@ -283,7 +283,7 @@ public function testCaseUpdateWithExistingCaseContact() {
   /**
    * Test case update with custom data
    */
-  public function testCaseUpdateCustom() {
+  public function testCaseUpdateCustom(): void {
     $ids = $this->entityCustomGroupWithSingleFieldCreate(__FUNCTION__, __FILE__);
     $params = $this->_params;
 
@@ -320,7 +320,7 @@ public function testCaseUpdateCustom() {
   /**
    * Test delete function with valid parameters.
    */
-  public function testCaseDelete() {
+  public function testCaseDelete(): void {
     // Create Case
     $result = $this->callAPISuccess('case', 'create', $this->_params);
 
@@ -351,7 +351,7 @@ public function testCaseDelete() {
    * Test Case role relationship is correctly created
    * for contacts.
    */
-  public function testCaseRoleRelationships() {
+  public function testCaseRoleRelationships(): void {
     // Create Case
     $case = $this->callAPISuccess('case', 'create', $this->_params);
     $relType = $this->relationshipTypeCreate(['name_a_b' => 'Test AB', 'name_b_a' => 'Test BA', 'contact_type_b' => 'Individual']);
@@ -387,7 +387,7 @@ public function testCaseRoleRelationships() {
   /**
    * Test get function based on activity.
    */
-  public function testCaseGetByActivity() {
+  public function testCaseGetByActivity(): void {
     // Create Case
     $result = $this->callAPISuccess('case', 'create', $this->_params);
     $id = $result['id'];
@@ -409,7 +409,7 @@ public function testCaseGetByActivity() {
   /**
    * Test get function based on contact id.
    */
-  public function testCaseGetByContact() {
+  public function testCaseGetByContact(): void {
     // Create Case
     $result = $this->callAPISuccess('case', 'create', $this->_params);
     $id = $result['id'];
@@ -428,7 +428,7 @@ public function testCaseGetByContact() {
   /**
    * Test get function based on subject.
    */
-  public function testCaseGetBySubject() {
+  public function testCaseGetBySubject(): void {
     // Create Case
     $result = $this->callAPISuccess('case', 'create', $this->_params);
     $id = $result['id'];
@@ -447,7 +447,7 @@ public function testCaseGetBySubject() {
   /**
    * Test get function based on wrong subject.
    */
-  public function testCaseGetByWrongSubject() {
+  public function testCaseGetByWrongSubject(): void {
     $this->callAPISuccess('case', 'create', $this->_params);
 
     // Append 'wrong' to subject so that it is no longer the same.
@@ -461,7 +461,7 @@ public function testCaseGetByWrongSubject() {
   /**
    * Test get function with no criteria.
    */
-  public function testCaseGetNoCriteria() {
+  public function testCaseGetNoCriteria(): void {
     $result = $this->callAPISuccess('case', 'create', $this->_params);
     $id = $result['id'];
 
@@ -475,7 +475,7 @@ public function testCaseGetNoCriteria() {
   /**
    * Test activity api create for case activities.
    */
-  public function testCaseActivityCreate() {
+  public function testCaseActivityCreate(): void {
     $params = $this->_params;
     $case = $this->callAPISuccess('case', 'create', $params);
     $params = [
@@ -514,7 +514,7 @@ public function testCaseActivityCreate() {
     $this->assertContainsEquals($case['id'], $result['case_id']);
   }
 
-  public function testCaseGetByStatus() {
+  public function testCaseGetByStatus(): void {
     // Create 2 cases with different status ids.
     $case1 = $this->callAPISuccess('Case', 'create', [
       'contact_id' => 17,
@@ -538,7 +538,7 @@ public function testCaseGetByStatus() {
     $this->assertEquals($case1['id'], $result['id']);
   }
 
-  public function testCaseGetWithRoles() {
+  public function testCaseGetWithRoles(): void {
     $case1 = $this->callAPISuccess('Case', 'create', [
       'contact_id' => 17,
       'subject' => "Test case with roles",
@@ -569,7 +569,7 @@ public function testCaseGetWithRoles() {
    * Test that case role is not assigned to logged in user if you've unchecked
    * the assign to creator in the case type definition.
    */
-  public function testCaseGetWithRolesNoCreator() {
+  public function testCaseGetWithRolesNoCreator(): void {
     // Copy and adjust stock case type so that assign role to creator is not checked
     $caseType = $this->callAPISuccess('CaseType', 'get', ['id' => $this->caseTypeId]);
     $newCaseType = $caseType['values'][$this->caseTypeId];
@@ -607,7 +607,7 @@ public function testCaseGetWithRolesNoCreator() {
     $this->callAPISuccess('CaseType', 'delete', ['id' => $newCaseType['id']]);
   }
 
-  public function testCaseGetWithDefinition() {
+  public function testCaseGetWithDefinition(): void {
     $case1 = $this->callAPISuccess('Case', 'create', [
       'contact_id' => 17,
       'subject' => "Test case with definition",
@@ -632,7 +632,7 @@ public function testCaseGetWithDefinition() {
     $this->assertNotEmpty($def['caseRoles'][0]['creator']);
   }
 
-  public function testCaseGetTags() {
+  public function testCaseGetTags(): void {
     $case1 = $this->callAPISuccess('Case', 'create', [
       'contact_id' => 17,
       'subject' => "Test case with tags",
@@ -669,7 +669,7 @@ public function testCaseGetTags() {
    *
    * @throws \Exception
    */
-  public function testCaseGetChainedOp() {
+  public function testCaseGetChainedOp(): void {
     $contact1 = $this->individualCreate([], 1);
     $contact2 = $this->individualCreate([], 2);
     $case1 = $this->callAPISuccess('Case', 'create', [
@@ -717,7 +717,7 @@ public function testCaseGetChainedOp() {
    *
    * For multi-client cases, should order by the first client.
    */
-  public function testCaseGetOrderByClient() {
+  public function testCaseGetOrderByClient(): void {
     $contact1 = $this->individualCreate(['first_name' => 'Aa', 'last_name' => 'Zz']);
     $contact2 = $this->individualCreate(['first_name' => 'Bb', 'last_name' => 'Zz']);
     $contact3 = $this->individualCreate(['first_name' => 'Cc', 'last_name' => 'Xx']);
@@ -785,7 +785,7 @@ public function testCaseGetOrderByClient() {
    *
    * For multi-client cases, case clients should not be returned in duplicates for contacts.
    */
-  public function testCaseGetDoesNotReturnClientsAsPartOfRelatedContacts() {
+  public function testCaseGetDoesNotReturnClientsAsPartOfRelatedContacts(): void {
     $contact1 = $this->individualCreate(['first_name' => 'Aa', 'last_name' => 'Zz']);
     $contact2 = $this->individualCreate(['first_name' => 'Bb', 'last_name' => 'Zz']);
     $relContact = $this->individualCreate(['first_name' => 'Rel', 'last_name' => 'Contact']);
@@ -834,7 +834,7 @@ public function testCaseGetDoesNotReturnClientsAsPartOfRelatedContacts() {
    *
    * @throws \Exception
    */
-  public function testCaseAddtimeline() {
+  public function testCaseAddtimeline(): void {
     $caseSpec = [
       'title' => 'Application with Definition',
       'name' => 'Application_with_Definition',
@@ -897,7 +897,7 @@ public function testCaseAddtimeline() {
    *
    * 2 cases should be mergeable into 1
    */
-  public function testCaseMerge() {
+  public function testCaseMerge(): void {
     $contact1 = $this->individualCreate([], 1);
     $case1 = $this->callAPISuccess('Case', 'create', [
       'contact_id' => $contact1,
@@ -918,7 +918,7 @@ public function testCaseMerge() {
     $this->assertEquals(1, $result['is_deleted']);
   }
 
-  public function testTimestamps() {
+  public function testTimestamps(): void {
     $params = $this->_params;
     $case_created = $this->callAPISuccess('case', 'create', $params);
 
diff --git a/tests/phpunit/api/v3/CaseTypeTest.php b/tests/phpunit/api/v3/CaseTypeTest.php
index 0a824c394077..7f9dbdba8580 100644
--- a/tests/phpunit/api/v3/CaseTypeTest.php
+++ b/tests/phpunit/api/v3/CaseTypeTest.php
@@ -61,14 +61,14 @@ public function tearDown(): void {
   /**
    * Check with empty array.
    */
-  public function testCaseTypeCreateEmpty() {
+  public function testCaseTypeCreateEmpty(): void {
     $this->callAPIFailure('CaseType', 'create', []);
   }
 
   /**
    * Check if required fields are not passed.
    */
-  public function testCaseTypeCreateWithoutRequired() {
+  public function testCaseTypeCreateWithoutRequired(): void {
     $params = [
       'name' => 'this case should fail',
     ];
@@ -86,7 +86,7 @@ public function testCaseTypeCreateWithoutRequired() {
    *
    * Success expected.
    */
-  public function testCaseTypeCreate() {
+  public function testCaseTypeCreate(): void {
     // Create Case Type.
     $params = [
       'title' => 'Application',
@@ -107,7 +107,7 @@ public function testCaseTypeCreate() {
   /**
    * Create a case with an invalid name.
    */
-  public function testCaseTypeCreate_invalidName() {
+  public function testCaseTypeCreate_invalidName(): void {
     // Create Case Type
     $params = [
       'title' => 'Application',
@@ -123,7 +123,7 @@ public function testCaseTypeCreate_invalidName() {
   /**
    * Test update (create with id) function with valid parameters.
    */
-  public function testCaseTypeUpdate() {
+  public function testCaseTypeUpdate(): void {
     // Create Case Type
     $params = [
       'title' => 'Application',
@@ -149,7 +149,7 @@ public function testCaseTypeUpdate() {
   /**
    * Test delete function with valid parameters.
    */
-  public function testCaseTypeDelete_New() {
+  public function testCaseTypeDelete_New(): void {
     // Create Case Type.
     $params = [
       'title' => 'Application',
@@ -172,7 +172,7 @@ public function testCaseTypeDelete_New() {
    *
    * Success expected.
    */
-  public function testCaseTypeCreateWithDefinition() {
+  public function testCaseTypeCreateWithDefinition(): void {
     // Create Case Type
     $params = self::APPLICATION_WITH_DEFINITION_PARAMS;
     $result = $this->callAPISuccess('CaseType', 'create', $params);
@@ -191,7 +191,7 @@ public function testCaseTypeCreateWithDefinition() {
   /**
    * Create a CaseType+case then delete the CaseType.
    */
-  public function testCaseTypeDelete_InUse() {
+  public function testCaseTypeDelete_InUse(): void {
     // Create Case Type
     $params = self::APPLICATION_WITH_DEFINITION_PARAMS;
     $createCaseType = $this->callAPISuccess('CaseType', 'create', $params);
@@ -224,7 +224,7 @@ public function testCaseTypeDelete_InUse() {
    *
    * @throws \Exception
    */
-  public function testCaseStatusByCaseType() {
+  public function testCaseStatusByCaseType(): void {
     $statusName = md5(mt_rand());
     $template = $this->callAPISuccess('CaseType', 'getsingle', ['id' => $this->caseTypeId]);
     unset($template['id']);
@@ -241,7 +241,7 @@ public function testCaseStatusByCaseType() {
     $this->assertEquals($template['definition']['statuses'], array_values($result['values']));
   }
 
-  public function testDefinitionGroups() {
+  public function testDefinitionGroups(): void {
     $gid1 = $this->groupCreate(['name' => 'testDefinitionGroups1', 'title' => 'testDefinitionGroups1']);
     $gid2 = $this->groupCreate(['name' => 'testDefinitionGroups2', 'title' => 'testDefinitionGroups2']);
     $def = self::APPLICATION_WITH_DEFINITION_PARAMS;
diff --git a/tests/phpunit/api/v3/ClassAPITest.php b/tests/phpunit/api/v3/ClassAPITest.php
index 0bd35bb7661d..2cac54022de3 100644
--- a/tests/phpunit/api/v3/ClassAPITest.php
+++ b/tests/phpunit/api/v3/ClassAPITest.php
@@ -20,7 +20,7 @@ class class_api_test extends CiviUnitTestCase {
   /**
    * Test that error doesn't occur for non-existent file.
    */
-  public function testConstructor() {
+  public function testConstructor(): void {
     require_once 'api/class.api.php';
 
     // Check no params is local
diff --git a/tests/phpunit/api/v3/ConstantTest.php b/tests/phpunit/api/v3/ConstantTest.php
index b410f0611de2..204cefcf0e71 100644
--- a/tests/phpunit/api/v3/ConstantTest.php
+++ b/tests/phpunit/api/v3/ConstantTest.php
@@ -52,7 +52,7 @@ public function setUp(): void {
   /**
    * Test civicrm_constant_get( ) for unknown constant
    */
-  public function testUnknownConstant() {
+  public function testUnknownConstant(): void {
     $result = $this->callAPIFailure('constant', 'get', [
       'name' => 'thisTypeDoesNotExist',
     ]);
@@ -61,7 +61,7 @@ public function testUnknownConstant() {
   /**
    * Test civicrm_constant_get( 'activityStatus' )
    */
-  public function testActivityStatus() {
+  public function testActivityStatus(): void {
 
     $result = $this->callAPISuccess('constant', 'get', [
       'name' => 'activityStatus',
@@ -77,7 +77,7 @@ public function testActivityStatus() {
   /**
    * Test civicrm_constant_get( 'activityType' )
    */
-  public function testActivityType() {
+  public function testActivityType(): void {
     $result = $this->callAPISuccess('constant', 'get', [
       'name' => 'activityType',
     ]);
diff --git a/tests/phpunit/api/v3/ContributionPageTest.php b/tests/phpunit/api/v3/ContributionPageTest.php
index 235a3c6e06c5..77a63775b1ed 100644
--- a/tests/phpunit/api/v3/ContributionPageTest.php
+++ b/tests/phpunit/api/v3/ContributionPageTest.php
@@ -786,7 +786,7 @@ public function testSubmitMembershipPriceSetPaymentPaymentProcessorRecurInstantP
    * - the first creates a new membership, completed contribution, in progress recurring. Check these
    * - create another - end date should be extended
    */
-  //public function testSubmitMembershipPriceSetPaymentPaymentProcessorRecurInstantPaymentDifferentFrequency() {
+  //public function testSubmitMembershipPriceSetPaymentPaymentProcessorRecurInstantPaymentDifferentFrequency(): void {
   //  $this->doSubmitMembershipPriceSetPaymentPaymentProcessorRecurInstantPayment(array('duration_unit' => 'year', 'recur_frequency_unit' => 'month'));
   //}
 
diff --git a/tests/phpunit/api/v3/ContributionRecurTest.php b/tests/phpunit/api/v3/ContributionRecurTest.php
index f737d4b82e62..fa7b233431a2 100644
--- a/tests/phpunit/api/v3/ContributionRecurTest.php
+++ b/tests/phpunit/api/v3/ContributionRecurTest.php
@@ -74,7 +74,7 @@ public function testGetContributionRecur($version) {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testCreateContributionRecurWithToken() {
+  public function testCreateContributionRecurWithToken(): void {
     // create token
     $this->createLoggedInUser();
     $token = $this->callAPISuccess('PaymentToken', 'create', [
@@ -105,7 +105,7 @@ public function testDeleteContributionRecur($version) {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testGetFieldsContributionRecur() {
+  public function testGetFieldsContributionRecur(): void {
     $result = $this->callAPISuccess($this->_entity, 'getfields', ['action' => 'create']);
     $this->assertEquals(12, $result['values']['start_date']['type']);
   }
@@ -115,7 +115,7 @@ public function testGetFieldsContributionRecur() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testContributionRecurCancel() {
+  public function testContributionRecurCancel(): void {
     $result = $this->callAPISuccess($this->_entity, 'create', $this->params);
     $this->callAPISuccess('ContributionRecur', 'cancel', ['id' => $result['id'], 'cancel_reason' => 'just cos', 'processor_message' => 'big fail']);
     $cancelled = $this->callAPISuccess('ContributionRecur', 'getsingle', ['id' => $result['id']]);
diff --git a/tests/phpunit/api/v3/ContributionSoftTest.php b/tests/phpunit/api/v3/ContributionSoftTest.php
index c2d8b5718aee..b2fee1a36012 100644
--- a/tests/phpunit/api/v3/ContributionSoftTest.php
+++ b/tests/phpunit/api/v3/ContributionSoftTest.php
@@ -73,7 +73,7 @@ public function setUp(): void {
    *
    * @todo - this might be better broken down into more smaller tests
    */
-  public function testGetContributionSoft() {
+  public function testGetContributionSoft(): void {
     //We don't test for PCP fields because there's no PCP API, so we can't create campaigns.
     $p = [
       'contribution_id' => $this->_contributionId,
@@ -141,19 +141,19 @@ public function testGetContributionSoft() {
   /**
    * civicrm_contribution_soft.
    */
-  public function testCreateEmptyParamsContributionSoft() {
+  public function testCreateEmptyParamsContributionSoft(): void {
     $this->callAPIFailure('contribution_soft', 'create', [],
       'Mandatory key(s) missing from params array: contribution_id, amount, contact_id'
     );
   }
 
-  public function testCreateParamsWithoutRequiredKeysContributionSoft() {
+  public function testCreateParamsWithoutRequiredKeysContributionSoft(): void {
     $this->callAPIFailure('contribution_soft', 'create', [],
       'Mandatory key(s) missing from params array: contribution_id, amount, contact_id'
     );
   }
 
-  public function testCreateContributionSoftInvalidContact() {
+  public function testCreateContributionSoftInvalidContact(): void {
     $params = [
       'contact_id' => 999,
       'contribution_id' => $this->_contributionId,
@@ -166,7 +166,7 @@ public function testCreateContributionSoftInvalidContact() {
     );
   }
 
-  public function testCreateContributionSoftInvalidContributionId() {
+  public function testCreateContributionSoftInvalidContributionId(): void {
     $params = [
       'contribution_id' => 999999,
       'contact_id' => $this->_softIndividual1Id,
@@ -182,7 +182,7 @@ public function testCreateContributionSoftInvalidContributionId() {
   /**
    * Function tests that additional financial records are created when fee amount is recorded.
    */
-  public function testCreateContributionSoft() {
+  public function testCreateContributionSoft(): void {
     $params = [
       'contribution_id' => $this->_contributionId,
       'contact_id' => $this->_softIndividual1Id,
@@ -203,7 +203,7 @@ public function testCreateContributionSoft() {
    * To Update Soft Contribution.
    *
    */
-  public function testCreateUpdateContributionSoft() {
+  public function testCreateUpdateContributionSoft(): void {
     //create a soft credit
     $params = [
       'contribution_id' => $this->_contributionId,
@@ -267,19 +267,19 @@ public function testCreateUpdateContributionSoft() {
    * civicrm_contribution_soft_delete methods.
    *
    */
-  public function testDeleteEmptyParamsContributionSoft() {
+  public function testDeleteEmptyParamsContributionSoft(): void {
     $params = [];
     $this->callAPIFailure('contribution_soft', 'delete', $params);
   }
 
-  public function testDeleteWrongParamContributionSoft() {
+  public function testDeleteWrongParamContributionSoft(): void {
     $params = [
       'contribution_source' => 'SSF',
     ];
     $this->callAPIFailure('contribution_soft', 'delete', $params);
   }
 
-  public function testDeleteContributionSoft() {
+  public function testDeleteContributionSoft(): void {
     //create a soft credit
     $params = [
       'contribution_id' => $this->_contributionId,
@@ -302,7 +302,7 @@ public function testDeleteContributionSoft() {
    * Test civicrm_contribution_search with empty params.
    * All available contributions expected.
    */
-  public function testSearchEmptyParams() {
+  public function testSearchEmptyParams(): void {
     $p = [
       'contribution_id' => $this->_contributionId,
       'contact_id' => $this->_softIndividual1Id,
@@ -324,7 +324,7 @@ public function testSearchEmptyParams() {
   /**
    * Test civicrm_contribution_soft_search. Success expected.
    */
-  public function testSearch() {
+  public function testSearch(): void {
     $p1 = [
       'contribution_id' => $this->_contributionId,
       'contact_id' => $this->_softIndividual1Id,
diff --git a/tests/phpunit/api/v3/ContributionTest.php b/tests/phpunit/api/v3/ContributionTest.php
index c9deba8b08ba..1887fdb729f4 100644
--- a/tests/phpunit/api/v3/ContributionTest.php
+++ b/tests/phpunit/api/v3/ContributionTest.php
@@ -904,7 +904,7 @@ public function testCreateContributionNullOutThankyouDate(): void {
   /**
    * Create test with unique field name on source.
    */
-  public function testCreateContributionSourceInvalidContact() {
+  public function testCreateContributionSourceInvalidContact(): void {
 
     $params = [
       'contact_id' => 999,
@@ -989,7 +989,7 @@ public function testCreateContributionWithNoteUniqueNameAliases(): void {
   /**
    * This is the test for creating soft credits.
    */
-  public function testCreateContributionWithSoftCredit() {
+  public function testCreateContributionWithSoftCredit(): void {
     $contact2 = $this->callAPISuccess('Contact', 'create', [
       'display_name' => 'superman',
       'contact_type' => 'Individual',
@@ -1012,7 +1012,7 @@ public function testCreateContributionWithSoftCredit() {
     $this->callAPISuccess('contact', 'delete', ['id' => $contact2['id']]);
   }
 
-  public function testCreateContributionWithSoftCreditDefaults() {
+  public function testCreateContributionWithSoftCreditDefaults(): void {
     $contact2 = $this->callAPISuccess('Contact', 'create', [
       'display_name' => 'superman',
       'contact_type' => 'Individual',
@@ -1035,7 +1035,7 @@ public function testCreateContributionWithSoftCreditDefaults() {
   /**
    * Test creating contribution with Soft Credit by passing in honor_contact_id.
    */
-  public function testCreateContributionWithHonoreeContact() {
+  public function testCreateContributionWithHonoreeContact(): void {
     $contact2 = $this->callAPISuccess('Contact', 'create', [
       'display_name' => 'superman',
       'contact_type' => 'Individual',
@@ -1060,7 +1060,7 @@ public function testCreateContributionWithHonoreeContact() {
   /**
    * Function tests that additional financial records are created when fee amount is recorded.
    */
-  public function testCreateContributionWithFee() {
+  public function testCreateContributionWithFee(): void {
     $params = [
       'contact_id' => $this->individualID,
       'receive_date' => '20120511',
@@ -1163,7 +1163,7 @@ public function testCreateInvalidFinancialType(): void {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testValidNamedFinancialType() {
+  public function testValidNamedFinancialType(): void {
     $params = $this->_params;
     $params['financial_type_id'] = 'Donation';
     $this->callAPISuccess($this->entity, 'create', $params);
@@ -1209,7 +1209,7 @@ public function testCreateContributionPayLaterOnline(): void {
   /**
    * Function tests that additional financial records are created for online contribution with pending option.
    */
-  public function testCreateContributionPendingOnline() {
+  public function testCreateContributionPendingOnline(): void {
     CRM_Financial_BAO_PaymentProcessor::create($this->_processorParams);
     $contributionPage = $this->callAPISuccess('contribution_page', 'create', $this->pageParams);
     $this->assertAPISuccess($contributionPage);
@@ -1241,7 +1241,7 @@ public function testCreateContributionPendingOnline() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testCreateBAODefaults() {
+  public function testCreateBAODefaults(): void {
     unset($this->_params['contribution_source_id'], $this->_params['payment_instrument_id']);
     $contribution = $this->callAPISuccess('Contribution', 'create', $this->_params);
     $contribution = $this->callAPISuccess('Contribution', 'getsingle', [
@@ -1259,7 +1259,7 @@ public function testCreateBAODefaults() {
    *
    * @throws CRM_Core_Exception
    */
-  public function testDeleteChainedGetSingle() {
+  public function testDeleteChainedGetSingle(): void {
     $contribution = $this->callAPISuccess('Contribution', 'create', $this->_params);
     $contribution = $this->callAPISuccess('Contribution', 'getsingle', [
       'id' => $contribution['id'],
@@ -1274,7 +1274,7 @@ public function testDeleteChainedGetSingle() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testCreateUpdateContributionChangeTotal() {
+  public function testCreateUpdateContributionChangeTotal(): void {
     $contribution = $this->callAPISuccess('contribution', 'create', $this->_params);
     $lineItems = $this->callAPISuccess('line_item', 'getvalue', [
 
@@ -1313,7 +1313,7 @@ public function testCreateUpdateContributionChangeTotal() {
   /**
    * Function tests that line items, financial records are updated when pay later contribution is received.
    */
-  public function testCreateUpdateContributionPayLater() {
+  public function testCreateUpdateContributionPayLater(): void {
     $contributionParams = [
       'contact_id' => $this->individualID,
       'receive_date' => '2012-01-01',
@@ -1367,7 +1367,7 @@ public function testCreateUpdateContributionPaymentInstrument(): void {
   /**
    * Function tests that financial records are updated when Payment Instrument is changed when amount is negative.
    */
-  public function testCreateUpdateNegativeContributionPaymentInstrument() {
+  public function testCreateUpdateNegativeContributionPaymentInstrument(): void {
     $instrumentId = $this->_addPaymentInstrument();
     $contributionParams = [
       'contact_id' => $this->individualID,
@@ -1396,7 +1396,7 @@ public function testCreateUpdateNegativeContributionPaymentInstrument() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testCreateUpdateContributionRefund() {
+  public function testCreateUpdateContributionRefund(): void {
     $contributionParams = [
       'contact_id' => $this->individualID,
       'receive_date' => '2012-01-01',
@@ -1432,7 +1432,7 @@ public function testCreateUpdateContributionRefund() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testCreateUpdateChargebackContributionDefaultAccount() {
+  public function testCreateUpdateChargebackContributionDefaultAccount(): void {
     $contribution = $this->callAPISuccess('Contribution', 'create', $this->_params);
     $this->callAPISuccess('Contribution', 'create', [
       'id' => $contribution['id'],
@@ -1461,7 +1461,7 @@ public function testCreateUpdateChargebackContributionDefaultAccount() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testCreateUpdateChargebackContributionCustomAccount() {
+  public function testCreateUpdateChargebackContributionCustomAccount(): void {
     $financialAccount = $this->callAPISuccess('FinancialAccount', 'create', [
       'name' => 'Chargeback Account',
       'is_active' => TRUE,
@@ -1499,7 +1499,7 @@ public function testCreateUpdateChargebackContributionCustomAccount() {
    * financial type. It is not always configured but should be reflected
    * in the financial_trxn & financial_item table if it is.
    */
-  public function testCreateUpdateRefundContributionConfiguredContraAccount() {
+  public function testCreateUpdateRefundContributionConfiguredContraAccount(): void {
     $financialAccount = $this->callAPISuccess('FinancialAccount', 'create', [
       'name' => 'Refund Account',
       'is_active' => TRUE,
@@ -1535,7 +1535,7 @@ public function testCreateUpdateRefundContributionConfiguredContraAccount() {
    * Here we ensure that the civicrm_financial_trxn.trxn_id & the civicrm_contribution.trxn_id are set
    * when trxn_id is passed in.
    */
-  public function testCreateUpdateContributionRefundTrxnIDPassedIn() {
+  public function testCreateUpdateContributionRefundTrxnIDPassedIn(): void {
     $contributionParams = [
       'contact_id' => $this->individualID,
       'receive_date' => '2012-01-01',
@@ -1569,7 +1569,7 @@ public function testCreateUpdateContributionRefundTrxnIDPassedIn() {
    * when trxn_id is passed in but if refund_trxn_id is different then that
    * is kept for the refund transaction.
    */
-  public function testCreateUpdateContributionRefundRefundAndTrxnIDPassedIn() {
+  public function testCreateUpdateContributionRefundRefundAndTrxnIDPassedIn(): void {
     $contributionParams = [
       'contact_id' => $this->individualID,
       'receive_date' => '2012-01-01',
@@ -1604,7 +1604,7 @@ public function testCreateUpdateContributionRefundRefundAndTrxnIDPassedIn() {
    * when trxn_id is passed in but if refund_trxn_id isset but empty then that
    * is kept for the refund transaction.
    */
-  public function testCreateUpdateContributionRefundRefundNullTrxnIDPassedIn() {
+  public function testCreateUpdateContributionRefundRefundNullTrxnIDPassedIn(): void {
     $contributionParams = [
       'contact_id' => $this->individualID,
       'receive_date' => '2012-01-01',
@@ -1658,7 +1658,7 @@ public function testCreateUpdateContributionInValidStatusChange(): void {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testCreateUpdateContributionCancelPending() {
+  public function testCreateUpdateContributionCancelPending(): void {
     $contributionParams = [
       'contact_id' => $this->individualID,
       'receive_date' => '2012-01-01',
@@ -1689,7 +1689,7 @@ public function testCreateUpdateContributionCancelPending() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testCreateUpdateContributionChangeFinancialType() {
+  public function testCreateUpdateContributionChangeFinancialType(): void {
     $contributionParams = [
       'contact_id' => $this->individualID,
       'receive_date' => '2012-01-01',
@@ -1714,7 +1714,7 @@ public function testCreateUpdateContributionChangeFinancialType() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testCreateUpdateContributionWithFeeAmountChangeFinancialType() {
+  public function testCreateUpdateContributionWithFeeAmountChangeFinancialType(): void {
     $contributionParams = [
       'contact_id' => $this->individualID,
       'receive_date' => '2012-01-01',
@@ -1738,7 +1738,7 @@ public function testCreateUpdateContributionWithFeeAmountChangeFinancialType() {
   /**
    * Test that update does not change status id CRM-15105.
    */
-  public function testCreateUpdateWithoutChangingPendingStatus() {
+  public function testCreateUpdateWithoutChangingPendingStatus(): void {
     $contribution = $this->callAPISuccess('contribution', 'create', array_merge($this->_params, ['contribution_status_id' => 2]));
     $this->callAPISuccess('contribution', 'create', ['id' => $contribution['id'], 'source' => 'new source']);
     $contribution = $this->callAPISuccess('contribution', 'getsingle', [
@@ -1753,7 +1753,7 @@ public function testCreateUpdateWithoutChangingPendingStatus() {
    *
    * CHANGE: we require the API to do an incremental update
    */
-  public function testCreateUpdateContribution() {
+  public function testCreateUpdateContribution(): void {
     $contributionID = $this->contributionCreate([
       'contact_id' => $this->individualID,
       'trxn_id' => 212355,
@@ -1951,7 +1951,7 @@ public function testSearchEmptyParams(): void {
   /**
    * Test civicrm_contribution_search. Success expected.
    */
-  public function testSearch() {
+  public function testSearch(): void {
     $p1 = [
       'contact_id' => $this->individualID,
       'receive_date' => date('Ymd'),
@@ -2109,7 +2109,7 @@ public function testPayLater(): void {
   /**
    * Test to check whether contact billing address is used when no contribution address
    */
-  public function testBillingAddress() {
+  public function testBillingAddress(): void {
     $mut = new CiviMailUtils($this, TRUE);
     $this->swapMessageTemplateForTestTemplate();
     $this->createLoggedInUser();
@@ -2168,7 +2168,7 @@ public function testBillingAddress() {
    * Note that we are creating a logged in user because email goes out from
    * that person
    */
-  public function testCompleteTransactionFeeAmount() {
+  public function testCompleteTransactionFeeAmount(): void {
     $this->createLoggedInUser();
     $params = array_merge($this->_params, ['contribution_status_id' => 2]);
     $contribution = $this->callAPISuccess('contribution', 'create', $params);
@@ -2441,7 +2441,7 @@ public function testRepeatTransactionAcceptRecurID(): void {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testRepeatTransactionTestRecurId() {
+  public function testRepeatTransactionTestRecurId(): void {
     $contributionRecur = $this->callAPISuccess('ContributionRecur', 'create', [
       'contact_id' => $this->individualID,
       'frequency_interval' => '1',
@@ -2559,7 +2559,7 @@ public function testRepeatTransactionMembershipRenewCompletedContribution(): voi
    * a date which says it should be expired then the result of repeattransaction is to push that date
    * to be one membership term from 'now' with status 'new'.
    */
-  public function testRepeattransactionRenewMembershipOldMembership() {
+  public function testRepeattransactionRenewMembershipOldMembership(): void {
     $entities = $this->setUpAutoRenewMembership();
     $newStatusID = CRM_Core_PseudoConstant::getKey('CRM_Member_BAO_Membership', 'status_id', 'New');
     $membership = $this->callAPISuccess('Membership', 'create', [
@@ -2739,7 +2739,7 @@ public function testRepeatTransactionAlteredAmount(): void {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testRepeatTransactionPassedInFinancialType() {
+  public function testRepeatTransactionPassedInFinancialType(): void {
     $originalContribution = $this->setUpRecurringContribution();
 
     $this->callAPISuccess('Contribution', 'repeattransaction', [
@@ -2792,7 +2792,7 @@ public function testRepeatTransactionPassedInFinancialType() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testContributionOrder() {
+  public function testContributionOrder(): void {
     $this->createContributionAndMembershipOrder();
     $contribution = $this->callAPISuccess('contribution', 'get')['values'][$this->ids['Contribution'][0]];
     $this->assertEquals('Pending Label**', $contribution['contribution_status']);
@@ -2911,7 +2911,7 @@ public function testRepeatTransactionUpdatedFinancialType(): void {
   /**
    * CRM-16397 test appropriate action if campaign has been passed in.
    */
-  public function testRepeatTransactionPassedInCampaign() {
+  public function testRepeatTransactionPassedInCampaign(): void {
     $paymentProcessorID = $this->paymentProcessorCreate();
     $campaignID = $this->campaignCreate();
     $campaignID2 = $this->campaignCreate();
@@ -3051,7 +3051,7 @@ public function testRepeatTransactionUpdatedFinancialTypeAndNotEquals(): void {
   /**
    * Test completing a transaction does not 'mess' with net amount (CRM-15960).
    */
-  public function testCompleteTransactionNetAmountOK() {
+  public function testCompleteTransactionNetAmountOK(): void {
     $this->createLoggedInUser();
     $params = array_merge($this->_params, ['contribution_status_id' => 2]);
     unset($params['net_amount']);
@@ -3091,7 +3091,7 @@ public function testCompleteTransactionWithReceiptDateSet(): void {
   /**
    * CRM-1960 - Test to ensure that completetransaction respects the is_email_receipt setting
    */
-  public function testCompleteTransactionWithEmailReceiptInput() {
+  public function testCompleteTransactionWithEmailReceiptInput(): void {
     $contributionPage = $this->createReceiptableContributionPage();
 
     $this->_params['contribution_page_id'] = $contributionPage['id'];
@@ -3112,7 +3112,7 @@ public function testCompleteTransactionWithEmailReceiptInput() {
   /**
    * Test that $is_recur is assigned to the receipt.
    */
-  public function testCompleteTransactionForRecurring() {
+  public function testCompleteTransactionForRecurring(): void {
     $this->mut = new CiviMailUtils($this, TRUE);
     $this->swapMessageTemplateForTestTemplate();
     $recurring = $this->setUpRecurringContribution();
@@ -3170,7 +3170,7 @@ public function testCompleteTransactionWithEmailReceiptInputTrue(): void {
   /**
    * Complete the transaction using the template with all the possible.
    */
-  public function testCompleteTransactionWithTestTemplate() {
+  public function testCompleteTransactionWithTestTemplate(): void {
     $this->swapMessageTemplateForTestTemplate();
     $contribution = $this->setUpForCompleteTransaction();
     $this->callAPISuccess('contribution', 'completetransaction', [
@@ -4428,7 +4428,7 @@ protected function setUpForCompleteTransaction(): array {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testRepeatTransactionWithNonCreditCardDefault() {
+  public function testRepeatTransactionWithNonCreditCardDefault(): void {
     $contributionRecur = $this->callAPISuccess('ContributionRecur', 'create', [
       'contact_id' => $this->individualID,
       'installments' => '12',
@@ -4495,7 +4495,7 @@ public function testRepeatTransactionMembershipCreatePendingContribution(): void
    *
    * @throws \CRM_Core_Exception
    */
-  public function testSendMailWithAPISetFromDetails() {
+  public function testSendMailWithAPISetFromDetails(): void {
     $mut = new CiviMailUtils($this, TRUE);
     $contribution = $this->callAPISuccess('contribution', 'create', $this->_params);
     $this->callAPISuccess('contribution', 'sendconfirmation', [
@@ -4515,7 +4515,7 @@ public function testSendMailWithAPISetFromDetails() {
   /**
    * Test sending a mail via the API.
    */
-  public function testSendMailWithNoFromSetFallToDomain() {
+  public function testSendMailWithNoFromSetFallToDomain(): void {
     $this->createLoggedInUser();
     $mut = new CiviMailUtils($this, TRUE);
     $contribution = $this->callAPISuccess('contribution', 'create', $this->_params);
@@ -4537,7 +4537,7 @@ public function testSendMailWithNoFromSetFallToDomain() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testSendMailWithRepeatTransactionAPIFalltoDomain() {
+  public function testSendMailWithRepeatTransactionAPIFalltoDomain(): void {
     $this->createLoggedInUser();
     $mut = new CiviMailUtils($this, TRUE);
     $contribution = $this->setUpRepeatTransaction([], 'single');
@@ -4562,7 +4562,7 @@ public function testSendMailWithRepeatTransactionAPIFalltoDomain() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testSendMailWithRepeatTransactionAPIFalltoContributionPage() {
+  public function testSendMailWithRepeatTransactionAPIFalltoContributionPage(): void {
     $mut = new CiviMailUtils($this, TRUE);
     $contributionPage = $this->contributionPageCreate(['receipt_from_name' => 'CiviCRM LLC', 'receipt_from_email' => 'contributionpage@civicrm.org', 'is_email_receipt' => 1]);
     $paymentProcessorID = $this->paymentProcessorCreate();
@@ -5021,7 +5021,7 @@ public function testPaymentDontChangeReceiveDate(): void {
    * instrument too. If multiple Payment Recorded, last payment record payment (when No more due) instrument set to main
    * payment
    */
-  public function testPaymentVerifyPaymentInstrumentChange() {
+  public function testPaymentVerifyPaymentInstrumentChange(): void {
     // Create Pending contribution with pay later mode, with payment instrument Check
     $params = [
       'contact_id' => $this->individualID,
@@ -5068,7 +5068,7 @@ public function testPaymentVerifyPaymentInstrumentChange() {
   /**
    * Test the "clean money" functionality.
    */
-  public function testCleanMoney() {
+  public function testCleanMoney(): void {
     $params = [
       'contact_id' => $this->individualID,
       'financial_type_id' => 1,
diff --git a/tests/phpunit/api/v3/CountryTest.php b/tests/phpunit/api/v3/CountryTest.php
index 135f38364c88..a53fbdb183e0 100644
--- a/tests/phpunit/api/v3/CountryTest.php
+++ b/tests/phpunit/api/v3/CountryTest.php
@@ -32,7 +32,7 @@ public function setUp(): void {
   /**
    * @dataProvider versionThreeAndFour
    */
-  public function testCreateCountry() {
+  public function testCreateCountry(): void {
 
     $result = $this->callAPISuccess('country', 'create', $this->_params);
     $this->assertEquals(1, $result['count']);
@@ -44,7 +44,7 @@ public function testCreateCountry() {
   /**
    * @dataProvider versionThreeAndFour
    */
-  public function testDeleteCountry() {
+  public function testDeleteCountry(): void {
     //create one
     $create = $this->callAPISuccess('country', 'create', $this->_params);
 
@@ -60,7 +60,7 @@ public function testDeleteCountry() {
    * Test civicrm_phone_get with empty params.
    * @dataProvider versionThreeAndFour
    */
-  public function testGetEmptyParams() {
+  public function testGetEmptyParams(): void {
     $result = $this->callAPISuccess('Country', 'Get', []);
   }
 
@@ -68,7 +68,7 @@ public function testGetEmptyParams() {
    * Test civicrm_phone_get with wrong params.
    * @dataProvider versionThreeAndFour
    */
-  public function testGetWrongParams() {
+  public function testGetWrongParams(): void {
     $this->callAPIFailure('Country', 'Get', ['id' => 'abc']);
   }
 
@@ -76,7 +76,7 @@ public function testGetWrongParams() {
    * Test civicrm_phone_get - success expected.
    * @dataProvider versionThreeAndFour
    */
-  public function testGet() {
+  public function testGet(): void {
     $country = $this->callAPISuccess('Country', 'create', $this->_params);
     $params = [
       'iso_code' => $this->_params['iso_code'],
@@ -93,7 +93,7 @@ public function testGet() {
    * We check on the iso code (there should be only one iso code
    * @dataProvider versionThreeAndFour
    */
-  public function testCreateDuplicateFail() {
+  public function testCreateDuplicateFail(): void {
     $params = $this->_params;
     unset($params['id']);
     $this->callAPISuccess('country', 'create', $params);
@@ -108,7 +108,7 @@ public function testCreateDuplicateFail() {
    * Test that the list of states is in the correct format when chaining
    * and using sequential.
    */
-  public function testCountryStateChainSequential() {
+  public function testCountryStateChainSequential(): void {
     // first without specifying
     $result = $this->callAPISuccess('Country', 'getsingle', [
       'iso_code' => 'US',
diff --git a/tests/phpunit/api/v3/CustomApiTest.php b/tests/phpunit/api/v3/CustomApiTest.php
index 33c72bcb7c6b..1e93d52daa06 100644
--- a/tests/phpunit/api/v3/CustomApiTest.php
+++ b/tests/phpunit/api/v3/CustomApiTest.php
@@ -35,7 +35,7 @@ public function tearDown(): void {
    * This api is a bit 'special' in that it has a composite primary key rather
    * than using 'id', make sure that works too....
    */
-  public function testCustomApi() {
+  public function testCustomApi(): void {
     $this->installApi();
     $this->callAPISuccess('MailingProviderData', 'create', [
       'contact_identifier' => 'xyz',
diff --git a/tests/phpunit/api/v3/CustomFieldTest.php b/tests/phpunit/api/v3/CustomFieldTest.php
index fa1ae297e257..37b5000224fd 100644
--- a/tests/phpunit/api/v3/CustomFieldTest.php
+++ b/tests/phpunit/api/v3/CustomFieldTest.php
@@ -36,7 +36,7 @@ public function tearDown(): void {
   /**
    * Check with no label.
    */
-  public function testCustomFieldCreateWithoutLabel() {
+  public function testCustomFieldCreateWithoutLabel(): void {
     $customGroup = $this->customGroupCreate(['extends' => 'Individual', 'title' => 'text_test_group']);
     $params = [
       'custom_group_id' => $customGroup['id'],
@@ -57,7 +57,7 @@ public function testCustomFieldCreateWithoutLabel() {
   /**
    * Check with edit.
    */
-  public function testCustomFieldCreateWithEdit() {
+  public function testCustomFieldCreateWithEdit(): void {
     $customGroup = $this->customGroupCreate(['extends' => 'Individual', 'title' => 'text_test_group']);
     $params = [
       'custom_group_id' => $customGroup['id'],
@@ -82,7 +82,7 @@ public function testCustomFieldCreateWithEdit() {
   /**
    * Check without groupId.
    */
-  public function testCustomFieldCreateWithoutGroupID() {
+  public function testCustomFieldCreateWithoutGroupID(): void {
     $fieldParams = [
       'name' => 'test_textfield1',
       'label' => 'Name',
@@ -103,7 +103,7 @@ public function testCustomFieldCreateWithoutGroupID() {
   /**
    * Check for Each data type: loop through available form input types
    */
-  public function testCustomFieldCreateAllAvailableFormInputs() {
+  public function testCustomFieldCreateAllAvailableFormInputs(): void {
     $gid = $this->customGroupCreate(['extends' => 'Individual', 'title' => 'testAllFormInputs']);
 
     $dtype = $customFieldDataType = array_column(CRM_Core_BAO_CustomField::dataType(), 'id');
@@ -213,7 +213,7 @@ public function testCustomFieldCreateWithEmptyOptionGroup(): void {
   /**
    * Check with non-ascii labels
    */
-  public function testCustomFieldCreateWithNonAsciiLabel() {
+  public function testCustomFieldCreateWithNonAsciiLabel(): void {
     $customGroup = $this->customGroupCreate(['extends' => 'Contact', 'title' => 'select_test_group']);
     $params = [
       'custom_group_id' => $customGroup['id'],
@@ -235,7 +235,7 @@ public function testCustomFieldCreateWithNonAsciiLabel() {
   /**
    * Test custom field with existing option group.
    */
-  public function testCustomFieldExistingOptionGroup() {
+  public function testCustomFieldExistingOptionGroup(): void {
     $customGroup = $this->customGroupCreate(['extends' => 'Organization', 'title' => 'test_group']);
     $params = [
       'custom_group_id' => $customGroup['id'],
@@ -268,7 +268,7 @@ public function testCustomFieldExistingOptionGroup() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testUpdateCustomFieldAddOptionGroup() {
+  public function testUpdateCustomFieldAddOptionGroup(): void {
     $customGroup = $this->customGroupCreate(['extends' => 'Organization', 'title' => 'test_group']);
     $params = [
       'custom_group_id' => $customGroup['id'],
@@ -288,7 +288,7 @@ public function testUpdateCustomFieldAddOptionGroup() {
   /**
    * Test custom field get works & return param works
    */
-  public function testCustomFieldGetReturnOptions() {
+  public function testCustomFieldGetReturnOptions(): void {
     $customGroup = $this->customGroupCreate(['extends' => 'Individual', 'title' => 'test_group']);
     $customField = $this->customFieldCreate(['custom_group_id' => $customGroup['id']]);
 
@@ -303,7 +303,7 @@ public function testCustomFieldGetReturnOptions() {
   /**
    * Test custom field get works & return param works
    */
-  public function testCustomFieldGetReturnArray() {
+  public function testCustomFieldGetReturnArray(): void {
     $customGroup = $this->customGroupCreate(['extends' => 'Individual', 'title' => 'test_group']);
     $customField = $this->customFieldCreate(['custom_group_id' => $customGroup['id']]);
 
@@ -318,7 +318,7 @@ public function testCustomFieldGetReturnArray() {
   /**
    * Test custom field get works & return param works
    */
-  public function testCustomFieldGetReturnTwoOptions() {
+  public function testCustomFieldGetReturnTwoOptions(): void {
     $customGroup = $this->customGroupCreate(['extends' => 'Individual', 'test_group']);
     $customField = $this->customFieldCreate(['custom_group_id' => $customGroup['id']]);
 
@@ -331,7 +331,7 @@ public function testCustomFieldGetReturnTwoOptions() {
     $this->assertFalse(array_key_exists('label', $result));
   }
 
-  public function testCustomFieldCreateWithOptionValues() {
+  public function testCustomFieldCreateWithOptionValues(): void {
     $customGroup = $this->customGroupCreate(['extends' => 'Contact', 'title' => 'select_test_group']);
 
     $option_values = [
@@ -385,7 +385,7 @@ public function testCustomFieldCreateWithOptionValues() {
   /**
    * Check without Field ID.
    */
-  public function testCustomFieldDeleteWithoutFieldID() {
+  public function testCustomFieldDeleteWithoutFieldID(): void {
     $params = [];
     $customField = $this->callAPIFailure('custom_field', 'delete', $params,
       'Mandatory key(s) missing from params array: id');
@@ -394,7 +394,7 @@ public function testCustomFieldDeleteWithoutFieldID() {
   /**
    * Check without valid array.
    */
-  public function testCustomFieldDelete() {
+  public function testCustomFieldDelete(): void {
     $customGroup = $this->customGroupCreate(['extends' => 'Individual', 'title' => 'test_group']);
     $customField = $this->customFieldCreate(['custom_group_id' => $customGroup['id']]);
     $this->assertNotNull($customField['id']);
@@ -410,7 +410,7 @@ public function testCustomFieldDelete() {
   /**
    * Check That any associated Mapping Field Entries are also removed.
    */
-  public function testCustomFieldDeleteWithMappingField() {
+  public function testCustomFieldDeleteWithMappingField(): void {
     $customGroup = $this->customGroupCreate(['extends' => 'Individual', 'title' => 'test_group']);
     $customField = $this->customFieldCreate(['custom_group_id' => $customGroup['id']]);
     $this->assertNotNull($customField['id']);
@@ -438,7 +438,7 @@ public function testCustomFieldDeleteWithMappingField() {
   /**
    * Check for Option Value.
    */
-  public function testCustomFieldOptionValueDelete() {
+  public function testCustomFieldOptionValueDelete(): void {
     $customGroup = $this->customGroupCreate(['extends' => 'Contact', 'title' => 'ABC']);
     $customOptionValueFields = $this->customFieldOptionValueCreate($customGroup, 'fieldABC');
     $params = [
@@ -453,7 +453,7 @@ public function testCustomFieldOptionValueDelete() {
    * and "Activity.getfields" should return only their respective fields (not the other's fields),
    * and unrelated entities should return no custom fields.
    */
-  public function testGetfields_CrossEntityPollution() {
+  public function testGetfields_CrossEntityPollution(): void {
     $auxEntities = ['Email', 'Address', 'LocBlock', 'Membership', 'ContributionPage', 'ReportInstance'];
     $allEntities = array_merge(['Contact', 'Activity'], $auxEntities);
 
@@ -515,7 +515,7 @@ public function testGetfields_CrossEntityPollution() {
    *
    * Uses the "attachment" api for setting value.
    */
-  public function testCustomFileField() {
+  public function testCustomFileField(): void {
     $customGroup = $this->customGroupCreate(['title' => 'attachment_test_group']);
     $params = [
       'custom_group_id' => $customGroup['id'],
@@ -547,7 +547,7 @@ public function testCustomFileField() {
     $this->assertEquals($attachment['id'], $result[$cfId]);
   }
 
-  public function testUpdateCustomField() {
+  public function testUpdateCustomField(): void {
     $customGroup = $this->customGroupCreate(['extends' => 'Individual']);
     $params = ['id' => $customGroup['id'], 'is_active' => 0];
     $result = $this->callAPISuccess('CustomGroup', 'create', $params);
@@ -592,7 +592,7 @@ public function getCustomFieldKeys($getFieldsResult) {
   /**
    * @throws \CRM_Core_Exception
    */
-  public function testMakeSearchableContactReferenceFieldUnsearchable() {
+  public function testMakeSearchableContactReferenceFieldUnsearchable(): void {
     $this->customGroupCreate([
       'name' => 'testCustomGroup',
       'title' => 'testCustomGroup',
@@ -617,7 +617,7 @@ public function testMakeSearchableContactReferenceFieldUnsearchable() {
   /**
    * Test disabling a searchable contact reference field.
    */
-  public function testDisableSearchableContactReferenceField() {
+  public function testDisableSearchableContactReferenceField(): void {
     $customGroup = $this->customGroupCreate([
       'name' => 'testCustomGroup',
       'title' => 'testCustomGroup',
@@ -639,7 +639,7 @@ public function testDisableSearchableContactReferenceField() {
     $this->callAPISuccess('CustomField', 'create', $params);
   }
 
-  public function testLegacyHtmlType() {
+  public function testLegacyHtmlType(): void {
     $customGroup = $this->customGroupCreate([
       'name' => 'testCustomGroup',
       'title' => 'testCustomGroup',
@@ -699,7 +699,7 @@ public function testLegacyHtmlType() {
     $this->assertEquals('SingleSelect', $result['values'][0]['label']);
   }
 
-  public function testLegacyStateCountryTypes() {
+  public function testLegacyStateCountryTypes(): void {
     $customGroup = $this->customGroupCreate([
       'name' => 'testCustomGroup',
       'title' => 'testCustomGroup',
diff --git a/tests/phpunit/api/v3/CustomGroupTest.php b/tests/phpunit/api/v3/CustomGroupTest.php
index e50a2aa62b48..66a38936c49c 100644
--- a/tests/phpunit/api/v3/CustomGroupTest.php
+++ b/tests/phpunit/api/v3/CustomGroupTest.php
@@ -53,7 +53,7 @@ public function tearDown(): void {
    * code. The SyntaxConformance is capable of testing this for all entities on create
    * & delete (& it would be easy to add if not there)
    */
-  public function testCustomGroupCreateNoParam() {
+  public function testCustomGroupCreateNoParam(): void {
     $customGroup = $this->callAPIFailure('custom_group', 'create', [],
       'Mandatory key(s) missing from params array: title, extends'
     );
@@ -62,7 +62,7 @@ public function testCustomGroupCreateNoParam() {
   /**
    * Check with empty array.
    */
-  public function testCustomGroupCreateNoExtends() {
+  public function testCustomGroupCreateNoExtends(): void {
     $params = [
       'domain_id' => 1,
       'title' => 'Test_Group_1',
@@ -83,7 +83,7 @@ public function testCustomGroupCreateNoExtends() {
   /**
    * Check with empty array.
    */
-  public function testCustomGroupCreateInvalidExtends() {
+  public function testCustomGroupCreateInvalidExtends(): void {
     $params = [
       'domain_id' => 1,
       'title' => 'Test_Group_1',
@@ -104,7 +104,7 @@ public function testCustomGroupCreateInvalidExtends() {
   /**
    * Check with a string instead of array for extends.
    */
-  public function testCustomGroupCreateExtendsString() {
+  public function testCustomGroupCreateExtendsString(): void {
     $params = [
       'domain_id' => 1,
       'title' => 'Test_Group_1',
@@ -124,7 +124,7 @@ public function testCustomGroupCreateExtendsString() {
   /**
    * Check with valid array.
    */
-  public function testCustomGroupCreate() {
+  public function testCustomGroupCreate(): void {
     $params = [
       'title' => 'Test_Group_1',
       'name' => 'test_group_1',
@@ -145,7 +145,7 @@ public function testCustomGroupCreate() {
   /**
    * Check with valid array.
    */
-  public function testCustomGroupGetFields() {
+  public function testCustomGroupGetFields(): void {
     $params = [
       'options' => ['get_options' => 'style'],
     ];
@@ -162,7 +162,7 @@ public function testCustomGroupGetFields() {
   /**
    * Check with extends array length greater than 1
    */
-  public function testCustomGroupExtendsMultipleCreate() {
+  public function testCustomGroupExtendsMultipleCreate(): void {
     $params = [
       'title' => 'Test_Group_1',
       'name' => 'test_group_1',
@@ -181,7 +181,7 @@ public function testCustomGroupExtendsMultipleCreate() {
   /**
    * Check with style missing from params array.
    */
-  public function testCustomGroupCreateNoStyle() {
+  public function testCustomGroupCreateNoStyle(): void {
     $params = [
       'title' => 'Test_Group_1',
       'name' => 'test_group_1',
@@ -201,7 +201,7 @@ public function testCustomGroupCreateNoStyle() {
   /**
    * Check without title.
    */
-  public function testCustomGroupCreateNoTitle() {
+  public function testCustomGroupCreateNoTitle(): void {
     $params = [
       'extends' => ['Contact'],
       'weight' => 5,
@@ -218,7 +218,7 @@ public function testCustomGroupCreateNoTitle() {
   /**
    * Check for household without weight.
    */
-  public function testCustomGroupCreateHouseholdNoWeight() {
+  public function testCustomGroupCreateHouseholdNoWeight(): void {
     $params = [
       'title' => 'Test_Group_3',
       'name' => 'test_group_3',
@@ -239,7 +239,7 @@ public function testCustomGroupCreateHouseholdNoWeight() {
   /**
    * Check for Contribution Donation.
    */
-  public function testCustomGroupCreateContributionDonation() {
+  public function testCustomGroupCreateContributionDonation(): void {
     $params = [
       'title' => 'Test_Group_6',
       'name' => 'test_group_6',
@@ -260,7 +260,7 @@ public function testCustomGroupCreateContributionDonation() {
   /**
    * Check with valid array.
    */
-  public function testCustomGroupCreateGroup() {
+  public function testCustomGroupCreateGroup(): void {
     $params = [
       'domain_id' => 1,
       'title' => 'Test_Group_8',
@@ -282,7 +282,7 @@ public function testCustomGroupCreateGroup() {
   /**
    * Test an empty update does not trigger e-notices when is_multiple has been set.
    */
-  public function testCustomGroupEmptyUpdate() {
+  public function testCustomGroupEmptyUpdate(): void {
     $customGroup = $this->callAPISuccess('CustomGroup', 'create', array_merge($this->_params, ['is_multiple' => 1]));
     $this->callAPISuccess('CustomGroup', 'create', ['id' => $customGroup['id']]);
   }
@@ -291,7 +291,7 @@ public function testCustomGroupEmptyUpdate() {
    * Test an update when is_multiple is an emtpy string this can occur in form submissions for custom groups that extend activites.
    * dev/core#227.
    */
-  public function testCustomGroupEmptyisMultipleUpdate() {
+  public function testCustomGroupEmptyisMultipleUpdate(): void {
     $customGroup = $this->callAPISuccess('CustomGroup', 'create', array_merge($this->_params, ['is_multiple' => 0]));
     $this->callAPISuccess('CustomGroup', 'create', ['id' => $customGroup['id'], 'is_multiple' => '']);
   }
@@ -299,7 +299,7 @@ public function testCustomGroupEmptyisMultipleUpdate() {
   /**
    * Check with Activity - Meeting Type
    */
-  public function testCustomGroupCreateActivityMeeting() {
+  public function testCustomGroupCreateActivityMeeting(): void {
     $params = [
       'title' => 'Test_Group_10',
       'name' => 'test_group_10',
@@ -321,7 +321,7 @@ public function testCustomGroupCreateActivityMeeting() {
   /**
    * Check without GroupID.
    */
-  public function testCustomGroupDeleteWithoutGroupID() {
+  public function testCustomGroupDeleteWithoutGroupID(): void {
     $customGroup = $this->callAPIFailure('custom_group', 'delete', []);
     $this->assertEquals($customGroup['error_message'], 'Mandatory key(s) missing from params array: id');
   }
@@ -329,7 +329,7 @@ public function testCustomGroupDeleteWithoutGroupID() {
   /**
    * Check with valid custom group id.
    */
-  public function testCustomGroupDelete() {
+  public function testCustomGroupDelete(): void {
     $customGroup = $this->customGroupCreate(['extends' => 'Individual', 'title' => 'test_group']);
     $params = [
       'id' => $customGroup['id'],
@@ -341,7 +341,7 @@ public function testCustomGroupDelete() {
   /**
    * Main success get function.
    */
-  public function testGetCustomGroupSuccess() {
+  public function testGetCustomGroupSuccess(): void {
 
     $this->callAPISuccess($this->_entity, 'create', $this->_params);
     $params = [];
@@ -355,7 +355,7 @@ public function testGetCustomGroupSuccess() {
     }
   }
 
-  public function testUpdateCustomGroup() {
+  public function testUpdateCustomGroup(): void {
     $customGroup = $this->customGroupCreate();
     $customGroupId = $customGroup['id'];
 
@@ -372,7 +372,7 @@ public function testUpdateCustomGroup() {
    * Test that as per the form that if the extends column is passed as
    * - ['ParticipantEventType', [4]] Where 4 = Meeting Event Type that we can create a custom group correctly
    */
-  public function testParticipantEntityCustomGroup() {
+  public function testParticipantEntityCustomGroup(): void {
     $customGroup = $this->callAPISuccess($this->_entity, 'create', array_merge($this->_params, ['extends' => ['ParticipantEventType', [4]]]));
     $result = array_shift($customGroup['values']);
     $this->assertEquals(3, $result['extends_entity_column_id']);
@@ -383,7 +383,7 @@ public function testParticipantEntityCustomGroup() {
   /**
    * Test that without any fields we can change the entity type of the custom group and fields are correctly updated
    */
-  public function testChangeEntityCustomGroup() {
+  public function testChangeEntityCustomGroup(): void {
     $customGroup = $this->callAPISuccess($this->_entity, 'create', array_merge($this->_params, ['extends' => ['ParticipantEventType', [4]]]));
     $result = array_shift($customGroup['values']);
     $this->assertEquals(3, $result['extends_entity_column_id']);
diff --git a/tests/phpunit/api/v3/CustomSearchTest.php b/tests/phpunit/api/v3/CustomSearchTest.php
index 8c73a3c1d12b..906a12c6def8 100644
--- a/tests/phpunit/api/v3/CustomSearchTest.php
+++ b/tests/phpunit/api/v3/CustomSearchTest.php
@@ -13,7 +13,7 @@ public function setUp(): void {
     $this->useTransaction(TRUE);
   }
 
-  public function testCustomSearch() {
+  public function testCustomSearch(): void {
     $result = $this->callAPISuccess('CustomSearch', 'create', [
       'label' => 'Invalid, overwritten',
       'description' => 'Longish description of the example search form',
diff --git a/tests/phpunit/api/v3/CustomValueContactTypeTest.php b/tests/phpunit/api/v3/CustomValueContactTypeTest.php
index 8dbf02be9295..d66a04cad288 100644
--- a/tests/phpunit/api/v3/CustomValueContactTypeTest.php
+++ b/tests/phpunit/api/v3/CustomValueContactTypeTest.php
@@ -130,7 +130,7 @@ public function tearDown(): void {
   /**
    * Test that custom fields is returned for correct contact type only.
    */
-  public function testGetFields() {
+  public function testGetFields(): void {
     $result = $this->callAPISuccess('Contact', 'getfields', []);
     $this->assertArrayHasKey("custom_{$this->individualFieldID}", $result['values'], 'If This fails there is probably a caching issue - failure in line' . __LINE__ . print_r(array_keys($result['values']), TRUE));
     $result = $this->callAPISuccess('Contact', 'getfields', [
@@ -150,7 +150,7 @@ public function testGetFields() {
   /**
    * Add  Custom data of Contact Type : Individual to a Contact type: Organization
    */
-  public function testAddIndividualCustomDataToOrganization() {
+  public function testAddIndividualCustomDataToOrganization(): void {
 
     $params = [
       'id' => $this->organizationContactID,
@@ -169,7 +169,7 @@ public function testAddIndividualCustomDataToOrganization() {
    * Add valid  Empty params to a Contact Type : Individual
    * note - don't copy & paste this - is of marginal value
    */
-  public function testAddCustomDataEmptyToIndividual() {
+  public function testAddCustomDataEmptyToIndividual(): void {
     $contact = $this->callAPIFailure('contact', 'create', [],
       'Mandatory key(s) missing from params array: contact_type'
     );
@@ -178,7 +178,7 @@ public function testAddCustomDataEmptyToIndividual() {
   /**
    * Add valid custom data to a Contact Type : Individual
    */
-  public function testAddValidCustomDataToIndividual() {
+  public function testAddValidCustomDataToIndividual(): void {
 
     $params = [
       'contact_id' => $this->individualContactID,
@@ -198,7 +198,7 @@ public function testAddValidCustomDataToIndividual() {
   /**
    * Add  Custom data of Contact Type : Individual , SubType : Student to a Contact type: Organization  Subtype: Sponsor
    */
-  public function testAddIndividualStudentCustomDataToOrganizationSponsor() {
+  public function testAddIndividualStudentCustomDataToOrganizationSponsor(): void {
 
     $params = [
       'contact_id' => $this->organizationSponsorContactID,
@@ -216,7 +216,7 @@ public function testAddIndividualStudentCustomDataToOrganizationSponsor() {
   /**
    * Add valid custom data to a Contact Type : Individual Subtype: Student
    */
-  public function testCreateValidCustomDataToIndividualStudent() {
+  public function testCreateValidCustomDataToIndividualStudent(): void {
 
     $params = [
       'contact_id' => $this->individualStudentContactID,
@@ -237,7 +237,7 @@ public function testCreateValidCustomDataToIndividualStudent() {
   /**
    * Add custom data of Individual Student to a Contact Type : Individual - parent
    */
-  public function testAddIndividualStudentCustomDataToIndividualParent() {
+  public function testAddIndividualStudentCustomDataToIndividualParent(): void {
 
     $params = [
       'contact_id' => $this->individualParentContactID,
@@ -256,7 +256,7 @@ public function testAddIndividualStudentCustomDataToIndividualParent() {
   /**
    * Retrieve Valid custom Data added to  Individual Contact Type.
    */
-  public function testRetrieveValidCustomDataToIndividual() {
+  public function testRetrieveValidCustomDataToIndividual(): void {
 
     $params = [
       'contact_id' => $this->individualContactID,
@@ -281,7 +281,7 @@ public function testRetrieveValidCustomDataToIndividual() {
   /**
    * Retrieve Valid custom Data added to  Individual Contact Type , Subtype : Student.
    */
-  public function testRetrieveValidCustomDataToIndividualStudent() {
+  public function testRetrieveValidCustomDataToIndividualStudent(): void {
 
     $params = [
       'contact_id' => $this->individualStudentContactID,
diff --git a/tests/phpunit/api/v3/CustomValueTest.php b/tests/phpunit/api/v3/CustomValueTest.php
index a7c77e082727..61c380e0c84d 100644
--- a/tests/phpunit/api/v3/CustomValueTest.php
+++ b/tests/phpunit/api/v3/CustomValueTest.php
@@ -86,7 +86,7 @@ public function tearDown(): void {
     parent::tearDown();
   }
 
-  public function testCreateCustomValue() {
+  public function testCreateCustomValue(): void {
     $this->_populateOptionAndCustomGroup();
     $this->_customField = $this->customFieldCreate(['custom_group_id' => $this->ids['string']['custom_group_id']]);
     $this->_customFieldID = $this->_customField['id'];
@@ -338,7 +338,7 @@ public function _testCustomValue($customField, $sqlOps, $type) {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testAlterOptionValue() {
+  public function testAlterOptionValue(): void {
     $this->_populateOptionAndCustomGroup('string');
 
     $selectField = $this->customFieldCreate([
@@ -419,7 +419,7 @@ public function testAlterOptionValue() {
     $this->assertEquals([$params[$radioName], $params[$controlFieldName]], $result[$multiSelectName]);
   }
 
-  public function testGettree() {
+  public function testGettree(): void {
     $cg = $this->callAPISuccess('CustomGroup', 'create', [
       'title' => 'TestGettree',
       'extends' => 'Individual',
@@ -476,7 +476,7 @@ public function testGettree() {
 
   }
 
-  public function testGettree_getfields() {
+  public function testGettree_getfields(): void {
     $fields = $this->callAPISuccess('CustomValue', 'getfields', ['api_action' => 'gettree']);
     $fields = $fields['values'];
     $this->assertTrue((bool) $fields['entity_id']['api.required']);
@@ -560,7 +560,7 @@ private function _testGetCustomValueMultiple() {
    * Test that specific custom values can be retrieved while using return with comma separated values as genererated by the api explorer.
    * ['return' => 'custom_1,custom_2']
    */
-  public function testGetCustomValueReturnMultipleApiExplorer() {
+  public function testGetCustomValueReturnMultipleApiExplorer(): void {
     [$cid, $customFieldValues] = $this->_testGetCustomValueMultiple();
     $result = $this->callAPISuccess('CustomValue', 'get', [
       'return' => implode(',', array_keys($customFieldValues)),
@@ -573,7 +573,7 @@ public function testGetCustomValueReturnMultipleApiExplorer() {
    * Test that specific custom values can be retrieved while using return with array style syntax.
    * ['return => ['custom_1', 'custom_2']]
    */
-  public function testGetCustomValueReturnMultipleArray() {
+  public function testGetCustomValueReturnMultipleArray(): void {
     [$cid, $customFieldValues] = $this->_testGetCustomValueMultiple();
     $result = $this->callAPISuccess('CustomValue', 'get', [
       'return' => array_keys($customFieldValues),
@@ -586,7 +586,7 @@ public function testGetCustomValueReturnMultipleArray() {
    * Test that specific custom values can be retrieved while using a list of return parameters.
    * [['return.custom_1' => '1'], ['return.custom_2' => '1']]
    */
-  public function testGetCustomValueReturnMultipleList() {
+  public function testGetCustomValueReturnMultipleList(): void {
     [$cid, $customFieldValues] = $this->_testGetCustomValueMultiple();
     $returnArray = [];
     foreach ($customFieldValues as $field => $value) {
@@ -600,7 +600,7 @@ public function testGetCustomValueReturnMultipleList() {
    * Test getdisplayvalue api and verify if it returns
    * the custom text for display.
    */
-  public function testGetDisplayValue() {
+  public function testGetDisplayValue(): void {
     [$cid, $customFieldValues] = $this->_testGetCustomValueMultiple();
     foreach ($customFieldValues as $field => $value) {
       [, $customFieldID] = explode("_", $field);
diff --git a/tests/phpunit/api/v3/DomainTest.php b/tests/phpunit/api/v3/DomainTest.php
index b02275cc70ce..02a7a94ae9b0 100644
--- a/tests/phpunit/api/v3/DomainTest.php
+++ b/tests/phpunit/api/v3/DomainTest.php
@@ -147,7 +147,7 @@ public function testGetCurrentDomainTwice($version) {
   /**
    * Test civicrm_domain_create.
    */
-  public function testCreate() {
+  public function testCreate(): void {
     $result = $this->callAPISuccess('domain', 'create', $this->params);
     $this->assertEquals($result['count'], 1);
     $this->assertNotNull($result['id']);
@@ -186,7 +186,7 @@ public function testUpdateDomainName($version) {
    *
    * See CRM-17430.
    */
-  public function testCreateDomainResult() {
+  public function testCreateDomainResult(): void {
     // First create a domain.
     $domain_result = $this->callAPISuccess('Domain', 'create', $this->params);
     $result_value = CRM_Utils_Array::first($domain_result['values']);
diff --git a/tests/phpunit/api/v3/EmailTest.php b/tests/phpunit/api/v3/EmailTest.php
index 7606259ffffd..9dc88ae2a280 100644
--- a/tests/phpunit/api/v3/EmailTest.php
+++ b/tests/phpunit/api/v3/EmailTest.php
@@ -443,7 +443,7 @@ public function testReplaceEmailWithId($version) {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testEmailOnHold() {
+  public function testEmailOnHold(): void {
     $params = [
       'contact_id' => $this->_contactID,
       'email' => 'api@a-team.com',
@@ -480,7 +480,7 @@ public function testEmailOnHold() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testSetBulkEmail() {
+  public function testSetBulkEmail(): void {
     $individualID = $this->individualCreate([]);
     $email = $this->callAPISuccessGetSingle('Email', ['contact_id' => $individualID]);
     $this->assertEquals(0, $email['is_bulkmail']);
@@ -498,7 +498,7 @@ public function testSetBulkEmail() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testGetlist() {
+  public function testGetlist(): void {
     $name = 'Scarabée';
     $emailMatchContactID = $this->individualCreate(['last_name' => $name, 'email' => 'bob@bob.com']);
     $emailMatchEmailID = $this->callAPISuccessGetValue('Email', ['return' => 'id', 'contact_id' => $emailMatchContactID]);
diff --git a/tests/phpunit/api/v3/EntityJoinTest.php b/tests/phpunit/api/v3/EntityJoinTest.php
index fbcbca262f9e..c23e76ec1918 100644
--- a/tests/phpunit/api/v3/EntityJoinTest.php
+++ b/tests/phpunit/api/v3/EntityJoinTest.php
@@ -22,7 +22,7 @@ public function setUp(): void {
     $this->useTransaction(TRUE);
   }
 
-  public function testJoinEmailToContact() {
+  public function testJoinEmailToContact(): void {
     $first = 'firstthisisatest';
     $last = 'lastthisisatest';
     $org = $this->organizationCreate(['organization_name' => 'Employer of one']);
diff --git a/tests/phpunit/api/v3/EntityTagTest.php b/tests/phpunit/api/v3/EntityTagTest.php
index c3cbf5a4adcb..c106ebff638a 100644
--- a/tests/phpunit/api/v3/EntityTagTest.php
+++ b/tests/phpunit/api/v3/EntityTagTest.php
@@ -65,7 +65,7 @@ public function setUp(): void {
    *
    * These failure tests are low value and may not be worth putting in v4.
    */
-  public function testFailureTests() {
+  public function testFailureTests(): void {
     $this->callAPIFailure('entity_tag', 'create', ['contact_id' => $this->_individualID],
       'tag_id is a required field'
     );
@@ -94,7 +94,7 @@ public function testContactEntityTagCreate($version) {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testAddDouble() {
+  public function testAddDouble(): void {
 
     $result = $this->callAPISuccess('entity_tag', 'create', $this->_params);
     $this->assertEquals($result['added'], 1);
@@ -113,7 +113,7 @@ public function testAddDouble() {
   /**
    * Test that get works without an entity.
    */
-  public function testGetNoEntityID() {
+  public function testGetNoEntityID(): void {
     $this->callAPISuccess('entity_tag', 'create', $this->_params);
     $result = $this->callAPISuccess($this->_entity, 'get', ['sequential' => 1, 'tag_id' => $this->_tagID]);
     $this->assertEquals($this->_individualID, $result['values'][0]['entity_id']);
@@ -144,7 +144,7 @@ public function testIndividualEntityTagGet($version) {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testMemoryLeak() {
+  public function testMemoryLeak(): void {
     $start = memory_get_usage();
     for ($i = 0; $i < 100; $i++) {
       $this->callAPISuccess('EntityTag', 'get', []);
@@ -157,7 +157,7 @@ public function testMemoryLeak() {
   /**
    * Test tag can be added to a household.
    */
-  public function testHouseholdEntityCreate() {
+  public function testHouseholdEntityCreate(): void {
     $params = [
       'contact_id' => $this->_householdID,
       'tag_id' => $this->_tagID,
@@ -195,7 +195,7 @@ public function testOrganizationEntityGet($version) {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testEntityTagDeleteNoTagId() {
+  public function testEntityTagDeleteNoTagId(): void {
     $entityTagParams = [
       'contact_id_i' => $this->_individualID,
       'contact_id_h' => $this->_householdID,
@@ -215,7 +215,7 @@ public function testEntityTagDeleteNoTagId() {
     $this->assertEquals($result['total_count'], 2);
   }
 
-  public function testEntityTagDeleteINDHH() {
+  public function testEntityTagDeleteINDHH(): void {
     $entityTagParams = [
       'contact_id_i' => $this->_individualID,
       'contact_id_h' => $this->_householdID,
@@ -234,7 +234,7 @@ public function testEntityTagDeleteINDHH() {
     $this->assertEquals($result['removed'], 2);
   }
 
-  public function testEntityTagDeleteHH() {
+  public function testEntityTagDeleteHH(): void {
     $entityTagParams = [
       'contact_id_i' => $this->_individualID,
       'contact_id_h' => $this->_householdID,
@@ -251,7 +251,7 @@ public function testEntityTagDeleteHH() {
     $this->assertEquals($result['removed'], 1);
   }
 
-  public function testEntityTagDeleteHHORG() {
+  public function testEntityTagDeleteHHORG(): void {
     $entityTagParams = [
       'contact_id_i' => $this->_individualID,
       'contact_id_h' => $this->_householdID,
@@ -270,7 +270,7 @@ public function testEntityTagDeleteHHORG() {
     $this->assertEquals($result['not_removed'], 1);
   }
 
-  public function testEntityTagCommonDeleteHH() {
+  public function testEntityTagCommonDeleteHH(): void {
     $entityTagParams = [
       'contact_id_i' => $this->_individualID,
       'contact_id_h' => $this->_householdID,
@@ -287,7 +287,7 @@ public function testEntityTagCommonDeleteHH() {
     $this->assertEquals($result['removed'], 1);
   }
 
-  public function testEntityTagCommonDeleteHHORG() {
+  public function testEntityTagCommonDeleteHHORG(): void {
     $entityTagParams = [
       'contact_id_i' => $this->_individualID,
       'contact_id_h' => $this->_householdID,
@@ -306,7 +306,7 @@ public function testEntityTagCommonDeleteHHORG() {
     $this->assertEquals($result['not_removed'], 1);
   }
 
-  public function testEntityTagJoin() {
+  public function testEntityTagJoin(): void {
     $org = $this->callAPISuccess('Contact', 'create', [
       'contact_type' => 'Organization',
       'organization_name' => 'Org123',
diff --git a/tests/phpunit/api/v3/EventTest.php b/tests/phpunit/api/v3/EventTest.php
index 1907bfd75ff3..e4c86b273372 100644
--- a/tests/phpunit/api/v3/EventTest.php
+++ b/tests/phpunit/api/v3/EventTest.php
@@ -100,7 +100,7 @@ public function tearDown(): void {
   /**
    * civicrm_event_get methods.
    */
-  public function testGetEventById() {
+  public function testGetEventById(): void {
     $params = [
       'id' => $this->_events[1]['id'],
     ];
@@ -111,7 +111,7 @@ public function testGetEventById() {
   /**
    * Test getLocationEvents() function invokes selectWhereClause() hook
    */
-  public function testGetEventWithPermissionHook() {
+  public function testGetEventWithPermissionHook(): void {
     $address = $this->callAPISuccess('address', 'create', [
       'contact_id' => 'null',
       'location_type_id' => 1,
@@ -134,7 +134,7 @@ public function testGetEventWithPermissionHook() {
     $this->assertEquals(0, count($result));
   }
 
-  public function testGetEventByEventTitle() {
+  public function testGetEventByEventTitle(): void {
 
     $params = [
       'event_title' => 'Annual CiviCRM meet',
@@ -162,7 +162,7 @@ public function testGetEventByWrongTitle($version) {
   /**
    * Skip api4 - this api uses deprecated query syntax
    */
-  public function testGetEventByIdSort() {
+  public function testGetEventByIdSort(): void {
     $params = [
       'return.sort' => 'id ASC',
       'return.max_results' => 1,
@@ -196,7 +196,7 @@ public function testGetEventByIdSort() {
    */
 
   /*
-  public function testGetIdOfEventByEventTitle() {
+  public function testGetIdOfEventByEventTitle(): void {
   $params = array(      'title' => 'Annual CiviCRM meet',
   'return' => 'id'
   );
@@ -209,7 +209,7 @@ public function testGetIdOfEventByEventTitle() {
    * Test 'is.Current' option. Existing event is 'old' so only current should be returned
    * FIXME: Api4
    */
-  public function testGetIsCurrent() {
+  public function testGetIsCurrent(): void {
     $params = [
       'isCurrent' => 1,
     ];
@@ -231,7 +231,7 @@ public function testGetIsCurrent() {
    * There has been a schema change & the api needs to buffer developers from it
    * FIXME: Api4
    */
-  public function testGetPaymentProcessorId() {
+  public function testGetPaymentProcessorId(): void {
     $params = $this->_params[0];
     $params['payment_processor_id'] = 1;
     $params['sequential'] = 1;
@@ -258,7 +258,7 @@ public function testInvalidData($version) {
    * Test 'is_full' option.
    * FIXME: Api4
    */
-  public function testGetSingleReturnIsFull() {
+  public function testGetSingleReturnIsFull(): void {
     $contactID = $this->individualCreate();
     $params = [
       'id' => $this->_eventIds[0],
@@ -292,7 +292,7 @@ public function testGetSingleReturnIsFull() {
    *
    * We need to ensure this is supported as an alias for financial_type_id.
    */
-  public function testCreateGetEventLegacyContributionTypeID() {
+  public function testCreateGetEventLegacyContributionTypeID(): void {
     $contributionTypeArray = ['contribution_type_id' => 3];
     if (isset($this->_params[0]['financial_type_id'])) {
       //in case someone edits $this->_params & invalidates this test :-)
@@ -352,7 +352,7 @@ public function testChainingGetLocBlock($version) {
    * Even if there is no loc block, at least the event should be returned.
    * http://forum.civicrm.org/index.php/topic,36113.0.html
    */
-  public function testChainingGetNonExistingLocBlock() {
+  public function testChainingGetNonExistingLocBlock(): void {
     $params = $this->_params[0];
     $result = $this->callAPISuccess($this->_entity, 'create', $params);
 
@@ -449,7 +449,7 @@ public function testSearchCustomFieldIsNull($version) {
    * https://issues.civicrm.org/jira/browse/CRM-16036
    * FIXME: Api4
    */
-  public function testEventGetCustomContactRefFieldCRM16036() {
+  public function testEventGetCustomContactRefFieldCRM16036(): void {
     // Create some contact.
     $test_contact_name = 'Contact, Test';
     $contact_save_result = $this->callAPISuccess('contact', 'create', [
@@ -546,7 +546,7 @@ public function testEventGetCustomFieldLte($version) {
    * CiviCRM to return 0 results.
    * Of course, CRM-16168 should also be fixed for this test to pass.
    */
-  public function testEventSearchCustomFieldWithChainedCall() {
+  public function testEventSearchCustomFieldWithChainedCall(): void {
     // Create a custom group, and add a custom contact reference field.
     $ids = $this->entityCustomGroupWithSingleFieldCreate(__FUNCTION__, __FILE__);
     $custom_field_id = $ids['custom_field_id'];
@@ -581,7 +581,7 @@ public function testEventSearchCustomFieldWithChainedCall() {
    * Test that an event with a price set can be created.
    * FIXME: Api4
    */
-  public function testCreatePaidEvent() {
+  public function testCreatePaidEvent(): void {
     //@todo alter API so that an integer is converted to an array
     $priceSetParams = ['price_set_id' => (array) 1, 'is_monetary' => 1];
     $result = $this->callAPISuccess('Event', 'Create', array_merge($this->_params[0], $priceSetParams));
@@ -650,7 +650,7 @@ public function testCreateEventSuccess($version) {
    * Test that passing in Unique field names works.
    * Skip api4 which doesn't use unique names
    */
-  public function testCreateEventSuccessUniqueFieldNames() {
+  public function testCreateEventSuccessUniqueFieldNames(): void {
     $this->_params[0]['event_start_date'] = $this->_params[0]['start_date'];
     unset($this->_params[1]['start_date']);
     $this->_params[0]['event_title'] = $this->_params[0]['title'];
@@ -797,7 +797,7 @@ public function testSearch($version) {
    *
    * return.offset and return.max_results test (CRM-5266)
    */
-  public function testSearchWithOffsetAndMaxResults() {
+  public function testSearchWithOffsetAndMaxResults(): void {
     $maxEvents = 5;
     $events = [];
     while ($maxEvents > 0) {
@@ -860,7 +860,7 @@ public function testgetfields($version) {
   /**
    * Test api_action param also works.
    */
-  public function testgetfieldsRest() {
+  public function testgetfieldsRest(): void {
     $params = ['api_action' => 'create'];
     $result = $this->callAPISuccess('event', 'getfields', $params);
     $this->assertEquals(1, $result['values']['is_active']['api.default']);
@@ -869,7 +869,7 @@ public function testgetfieldsRest() {
   /**
    * Skip api4 - output is different
    */
-  public function testgetfieldsGet() {
+  public function testgetfieldsGet(): void {
     $params = ['action' => 'get'];
     $result = $this->callAPISuccess('event', 'getfields', $params);
     $this->assertEquals('title', $result['values']['event_title']['name']);
@@ -878,7 +878,7 @@ public function testgetfieldsGet() {
   /**
    * Skip api4 - output is different
    */
-  public function testgetfieldsDelete() {
+  public function testgetfieldsDelete(): void {
     $params = ['action' => 'delete'];
     $result = $this->callAPISuccess('event', 'getfields', $params);
     $this->assertEquals(1, $result['values']['id']['api.required']);
@@ -927,7 +927,7 @@ public function testCreateFromTemplate($version) {
     $this->assertEquals(0, $eventResult['is_template'], print_r($eventResult, 1));
   }
 
-  public function testGetListLeadingZero() {
+  public function testGetListLeadingZero(): void {
     $this->callAPISuccess('Event', 'create', [
       'title' => "0765",
       'start_date' => "2022-04-04",
diff --git a/tests/phpunit/api/v3/ExceptionTest.php b/tests/phpunit/api/v3/ExceptionTest.php
index cd52cc2ab6a8..7d19ee16d083 100644
--- a/tests/phpunit/api/v3/ExceptionTest.php
+++ b/tests/phpunit/api/v3/ExceptionTest.php
@@ -30,7 +30,7 @@ protected function setUp(): void {
   /**
    * Test that when a dedupe exception is created the pair are saved from the merge cache.
    */
-  public function testCreatingAnExceptionRemovesFromCachedMergePairs() {
+  public function testCreatingAnExceptionRemovesFromCachedMergePairs(): void {
     $contact1 = $this->individualCreate();
     $contact2 = $this->individualCreate();
     $defaultRuleGroupID = $this->callAPISuccess('RuleGroup', 'getvalue', [
@@ -56,7 +56,7 @@ public function testCreatingAnExceptionRemovesFromCachedMergePairs() {
    *
    * @throws \Exception
    */
-  public function testExceptionSavesLowerIDFirst() {
+  public function testExceptionSavesLowerIDFirst(): void {
     $contact1 = $this->individualCreate();
     $contact2 = $this->individualCreate();
     $this->callAPISuccess('Exception', 'create', ['contact_id1' => $contact2, 'contact_id2' => $contact1]);
diff --git a/tests/phpunit/api/v3/ExtensionTest.php b/tests/phpunit/api/v3/ExtensionTest.php
index 1412fffd6eb4..d50a3cb14a65 100644
--- a/tests/phpunit/api/v3/ExtensionTest.php
+++ b/tests/phpunit/api/v3/ExtensionTest.php
@@ -35,7 +35,7 @@ public function tearDown(): void {
   /**
    * Test getremote.
    */
-  public function testGetremote() {
+  public function testGetremote(): void {
     $testsDir = dirname(dirname(dirname(dirname(__FILE__))));
     $this->createMockHandler([file_get_contents($testsDir . '/mock/extension_browser_results/single')]);
     $this->setUpClientWithHistoryContainer();
@@ -54,7 +54,7 @@ public function testGetremote() {
    * Test getting a single extension
    * @see https://issues.civicrm.org/jira/browse/CRM-20532
    */
-  public function testExtensionGetSingleExtension() {
+  public function testExtensionGetSingleExtension(): void {
     $result = $this->callAPISuccess('extension', 'get', ['key' => 'test.extension.manager.moduletest']);
     $this->assertEquals('test.extension.manager.moduletest', $result['values'][$result['id']]['key']);
     $this->assertEquals('module', $result['values'][$result['id']]['type']);
@@ -65,7 +65,7 @@ public function testExtensionGetSingleExtension() {
    * Test single Extension get with specific fields in return
    * @see https://issues.civicrm.org/jira/browse/CRM-20532
    */
-  public function testSingleExtensionGetWithReturnFields() {
+  public function testSingleExtensionGetWithReturnFields(): void {
     $result = $this->callAPISuccess('extension', 'get', ['key' => 'test.extension.manager.moduletest', 'return' => ['name', 'status', 'key']]);
     $this->assertEquals('test.extension.manager.moduletest', $result['values'][$result['id']]['key']);
     $this->assertFalse(isset($result['values'][$result['id']]['type']));
@@ -78,7 +78,7 @@ public function testSingleExtensionGetWithReturnFields() {
    * Note that this is likely to fail locally but will work on Jenkins due to the result count check
    * @see https://issues.civicrm.org/jira/browse/CRM-20532
    */
-  public function testExtensionGet() {
+  public function testExtensionGet(): void {
     $result = $this->callAPISuccess('extension', 'get', ['options' => ['limit' => 0]]);
     $testExtensionResult = $this->callAPISuccess('extension', 'get', ['key' => 'test.extension.manager.paymenttest']);
     $ext = $result['values'][$testExtensionResult['id']];
@@ -90,7 +90,7 @@ public function testExtensionGet() {
   /**
    * Filtering by status=installed or status=uninstalled should produce different results.
    */
-  public function testExtensionGetByStatus() {
+  public function testExtensionGetByStatus(): void {
     $installed = $this->callAPISuccess('extension', 'get', ['status' => 'installed', 'options' => ['limit' => 0]]);
     $uninstalled = $this->callAPISuccess('extension', 'get', ['status' => 'uninstalled', 'options' => ['limit' => 0]]);
     $disabled = $this->callAPISuccess('extension', 'get', ['status' => 'disabled', 'options' => ['limit' => 0]]);
@@ -109,7 +109,7 @@ public function testExtensionGetByStatus() {
     $this->assertEquals($all['count'], $installed['count'] + $uninstalled['count'] + $disabled['count']);
   }
 
-  public function testGetMultipleExtensions() {
+  public function testGetMultipleExtensions(): void {
     $result = $this->callAPISuccess('extension', 'get', ['key' => ['test.extension.manager.paymenttest', 'test.extension.manager.moduletest']]);
     $this->assertEquals(2, $result['count']);
   }
@@ -117,7 +117,7 @@ public function testGetMultipleExtensions() {
   /**
    * Test that extension get works with api request with parameter full_name as build by api explorer.
    */
-  public function testGetMultipleExtensionsApiExplorer() {
+  public function testGetMultipleExtensionsApiExplorer(): void {
     $result = $this->callAPISuccess('extension', 'get', ['full_name' => ['test.extension.manager.paymenttest', 'test.extension.manager.moduletest']]);
     $this->assertEquals(2, $result['count']);
   }
@@ -125,7 +125,7 @@ public function testGetMultipleExtensionsApiExplorer() {
   /**
    * Test that extension get can be filtered by id.
    */
-  public function testGetExtensionByID() {
+  public function testGetExtensionByID(): void {
     $result = $this->callAPISuccess('extension', 'get', ['id' => 2, 'return' => ['label']]);
     $this->assertEquals(1, $result['count']);
   }
diff --git a/tests/phpunit/api/v3/FinancialTypeACLTest.php b/tests/phpunit/api/v3/FinancialTypeACLTest.php
index 196fb773af43..a43227196458 100644
--- a/tests/phpunit/api/v3/FinancialTypeACLTest.php
+++ b/tests/phpunit/api/v3/FinancialTypeACLTest.php
@@ -89,7 +89,7 @@ public function tearDown(): void {
   /**
    * Test Get.
    */
-  public function testCreateACLContribution() {
+  public function testCreateACLContribution(): void {
     $this->enableFinancialACLs();
     $p = [
       'contact_id' => $this->_individualId,
@@ -150,7 +150,7 @@ public function testCreateACLContribution() {
   /**
    * Test that acl contributions can be retrieved.
    */
-  public function testGetACLContribution() {
+  public function testGetACLContribution(): void {
     $this->enableFinancialACLs();
 
     $this->setPermissions([
@@ -178,7 +178,7 @@ public function testGetACLContribution() {
   /**
    * Test checks that passing in line items suppresses the create mechanism.
    */
-  public function testCreateACLContributionChainedLineItems() {
+  public function testCreateACLContributionChainedLineItems(): void {
     $this->enableFinancialACLs();
     $params = [
       'contact_id' => $this->_individualId,
@@ -253,7 +253,7 @@ public function testCreateACLContributionChainedLineItems() {
   /**
    * Test that acl contributions can be edited.
    */
-  public function testEditACLContribution() {
+  public function testEditACLContribution(): void {
     $this->enableFinancialACLs();
     $contribution = $this->callAPISuccess('Contribution', 'create', $this->_params);
 
@@ -306,7 +306,7 @@ public function testDeleteACLContribution(): void {
     $this->assertEquals(1, $contribution['count']);
   }
 
-  public function testMembershipTypeACLFinancialTypeACL() {
+  public function testMembershipTypeACLFinancialTypeACL(): void {
     $contactID = $this->individualCreate();
     $this->contactMembershipCreate(['contact_id' => $contactID]);
     $this->enableFinancialACLs();
diff --git a/tests/phpunit/api/v3/FinancialTypeTest.php b/tests/phpunit/api/v3/FinancialTypeTest.php
index 44805af8d0c5..32f0e8258a34 100644
--- a/tests/phpunit/api/v3/FinancialTypeTest.php
+++ b/tests/phpunit/api/v3/FinancialTypeTest.php
@@ -114,7 +114,7 @@ public function testAssociatedFinancialAccountGetsCreated($apiVersion) {
     $this->assertEquals('INC', $result['account_type_code'], 'Financial account created is not an income account.');
   }
 
-  public function testMatchFinancialTypeOptions() {
+  public function testMatchFinancialTypeOptions(): void {
     // Just a string name, should be simple to match on
     $nonNumericOption = $this->callAPISuccess('FinancialType', 'create', [
       'name' => 'StringName',
diff --git a/tests/phpunit/api/v3/GroupContactTest.php b/tests/phpunit/api/v3/GroupContactTest.php
index bcd81b3efe31..f52e2874a103 100644
--- a/tests/phpunit/api/v3/GroupContactTest.php
+++ b/tests/phpunit/api/v3/GroupContactTest.php
@@ -92,7 +92,7 @@ public function tearDown(): void {
   /**
    * Test GroupContact.get by ID.
    */
-  public function testGet() {
+  public function testGet(): void {
     $params = [
       'contact_id' => $this->contactID,
     ];
@@ -104,7 +104,7 @@ public function testGet() {
     }
   }
 
-  public function testGetGroupID() {
+  public function testGetGroupID(): void {
     $params = [
       'group_id' => $this->groupID1,
       'api.group.get' => 1,
@@ -157,7 +157,7 @@ public function testDelete(): void {
     $this->assertEquals(1, $result['total_count']);
   }
 
-  public function testDeletePermanent() {
+  public function testDeletePermanent(): void {
     $result = $this->callAPISuccess('group_contact', 'get', ['contact_id' => $this->contactID]);
     $params = [
       'id' => $result['id'],
@@ -173,7 +173,7 @@ public function testDeletePermanent() {
    * CRM-19496 When id is used rather than contact_id and group_id ensure that remove function still works.
    *
    */
-  public function testDeleteWithId() {
+  public function testDeleteWithId(): void {
     $groupContactParams = [
       'contact_id' => $this->contactID,
       'group_id' => $this->groupID1,
@@ -192,7 +192,7 @@ public function testDeleteWithId() {
    * CRM-19496 When id is used rather than contact_id and group_id ensure that remove function still works.
    *
    */
-  public function testDeleteAndReAddWithId() {
+  public function testDeleteAndReAddWithId(): void {
     $groupContactParams = [
       'contact_id' => $this->contactID,
       'group_id' => $this->groupID1,
@@ -258,7 +258,7 @@ public function testDeleteWithPending(int $version): void {
   /**
    * CRM-19979 test that group cotnact delete action works when contact is in status of pendin and is a permanent delete.
    */
-  public function testPermanentDeleteWithPending() {
+  public function testPermanentDeleteWithPending(): void {
     $groupId3 = $this->groupCreate([
       'name' => 'Test Group 3',
       'domain_id' => 1,
@@ -285,7 +285,7 @@ public function testPermanentDeleteWithPending() {
    *
    * Test illustrates this (& ensures once fixed it will stay fixed).
    */
-  public function testAccurateCountWithSmartGroups() {
+  public function testAccurateCountWithSmartGroups(): void {
     $childGroupID = $this->groupCreate([
       'name' => 'Child group',
       'domain_id' => 1,
diff --git a/tests/phpunit/api/v3/GroupNestingTest.php b/tests/phpunit/api/v3/GroupNestingTest.php
index d6b8bbbce74a..be99e614ba54 100644
--- a/tests/phpunit/api/v3/GroupNestingTest.php
+++ b/tests/phpunit/api/v3/GroupNestingTest.php
@@ -73,7 +73,7 @@ protected function tearDown(): void {
    *
    * @dataProvider versionThreeAndFour
    */
-  public function testGet() {
+  public function testGet(): void {
     $params = [
       'parent_group_id' => $this->ids['Group']['parent'],
       'child_group_id' => $this->ids['Group']['child'],
@@ -96,7 +96,7 @@ public function testGet() {
    *
    * @dataProvider versionThreeAndFour
    */
-  public function testGetWithChildGroupId() {
+  public function testGetWithChildGroupId(): void {
     $params = [
       'child_group_id' => $this->ids['Group']['child3'],
     ];
@@ -125,7 +125,7 @@ public function testGetWithChildGroupId() {
    *
    * @dataProvider versionThreeAndFour
    */
-  public function testGetWithParentGroupId() {
+  public function testGetWithParentGroupId(): void {
     $params = [
       'parent_group_id' => $this->ids['Group']['parent'],
     ];
@@ -162,7 +162,7 @@ public function testGetWithParentGroupId() {
    *
    * @dataProvider versionThreeAndFour
    */
-  public function testGetEmptyResults() {
+  public function testGetEmptyResults(): void {
     $params = [
       'parent_group_id' => $this->ids['Group']['parent'],
       'child_group_id' => 700,
@@ -177,7 +177,7 @@ public function testGetEmptyResults() {
    *
    * @dataProvider versionThreeAndFour
    */
-  public function testCreate() {
+  public function testCreate(): void {
     $params = [
       'parent_group_id' => $this->ids['Group']['parent'],
       'child_group_id' => $this->ids['Group']['child2'],
@@ -192,7 +192,7 @@ public function testCreate() {
    *
    * @dataProvider versionThreeAndFour
    */
-  public function testDelete() {
+  public function testDelete(): void {
     $params = [
       'parent_group_id' => $this->ids['Group']['parent'],
       'child_group_id' => $this->ids['Group']['child'],
@@ -211,7 +211,7 @@ public function testDelete() {
    *
    * @dataProvider versionThreeAndFour
    */
-  public function testDeleteWithEmptyParams() {
+  public function testDeleteWithEmptyParams(): void {
     $this->callAPIFailure('group_nesting', 'delete', []);
   }
 
diff --git a/tests/phpunit/api/v3/GroupOrganizationTest.php b/tests/phpunit/api/v3/GroupOrganizationTest.php
index 58a171173d67..05686eb67e7f 100644
--- a/tests/phpunit/api/v3/GroupOrganizationTest.php
+++ b/tests/phpunit/api/v3/GroupOrganizationTest.php
@@ -48,7 +48,7 @@ protected function setUp(): void {
    *
    * @dataProvider versionThreeAndFour
    */
-  public function testGroupOrganizationGet() {
+  public function testGroupOrganizationGet(): void {
 
     $params = [
       'organization_id' => $this->_orgID,
@@ -66,7 +66,7 @@ public function testGroupOrganizationGet() {
    *
    * @dataProvider versionThreeAndFour
    */
-  public function testGroupOrganizationGetWithGroupId() {
+  public function testGroupOrganizationGetWithGroupId(): void {
     $createParams = [
       'organization_id' => $this->_orgID,
       'group_id' => $this->_groupID,
@@ -86,7 +86,7 @@ public function testGroupOrganizationGetWithGroupId() {
    *
    * @dataProvider versionThreeAndFour
    */
-  public function testGroupOrganizationGetWithEmptyParams() {
+  public function testGroupOrganizationGetWithEmptyParams(): void {
     $params = [];
     $result = $this->callAPISuccess('group_organization', 'get', $params);
 
@@ -98,7 +98,7 @@ public function testGroupOrganizationGetWithEmptyParams() {
    *
    * @dataProvider versionThreeAndFour
    */
-  public function testGroupOrganizationGetWithInvalidKeys() {
+  public function testGroupOrganizationGetWithInvalidKeys(): void {
     $params = [
       'invalid_key' => 1,
     ];
@@ -114,7 +114,7 @@ public function testGroupOrganizationGetWithInvalidKeys() {
    *
    * @dataProvider versionThreeAndFour
    */
-  public function testGroupOrganizationCreate() {
+  public function testGroupOrganizationCreate(): void {
     $params = [
       'organization_id' => $this->_orgID,
       'group_id' => $this->_groupID,
@@ -127,7 +127,7 @@ public function testGroupOrganizationCreate() {
    *
    * @dataProvider versionThreeAndFour
    */
-  public function testGroupOrganizationCreateTwice() {
+  public function testGroupOrganizationCreateTwice(): void {
     $params = [
       'organization_id' => $this->_orgID,
       'group_id' => $this->_groupID,
@@ -142,7 +142,7 @@ public function testGroupOrganizationCreateTwice() {
    *
    * @dataProvider versionThreeAndFour
    */
-  public function testGroupOrganizationCreateWithEmptyParams() {
+  public function testGroupOrganizationCreateWithEmptyParams(): void {
     $params = [];
     $result = $this->callAPIFailure('group_organization', 'create', $params);
     $this->assertEquals($result['error_message'], 'Mandatory key(s) missing from params array: group_id, organization_id');
@@ -153,7 +153,7 @@ public function testGroupOrganizationCreateWithEmptyParams() {
    *
    * @dataProvider versionThreeAndFour
    */
-  public function testGroupOrganizationCreateWithInvalidKeys() {
+  public function testGroupOrganizationCreateWithInvalidKeys(): void {
     $params = [
       'invalid_key' => 1,
     ];
@@ -168,7 +168,7 @@ public function testGroupOrganizationCreateWithInvalidKeys() {
    *
    * @dataProvider versionThreeAndFour
    */
-  public function testGroupOrganizationDeleteWithEmptyParams() {
+  public function testGroupOrganizationDeleteWithEmptyParams(): void {
     $params = [];
     $result = $this->callAPIFailure('group_organization', 'delete', $params);
     $this->assertEquals($result['error_message'], 'Mandatory key(s) missing from params array: id');
@@ -179,7 +179,7 @@ public function testGroupOrganizationDeleteWithEmptyParams() {
    *
    * @dataProvider versionThreeAndFour
    */
-  public function testGroupOrganizationDelete() {
+  public function testGroupOrganizationDelete(): void {
     $paramsC = [
       'organization_id' => $this->_orgID,
       'group_id' => $this->_groupID,
@@ -197,7 +197,7 @@ public function testGroupOrganizationDelete() {
    *
    * @dataProvider versionThreeAndFour
    */
-  public function testGroupOrganizationDeleteWithInvalidKey() {
+  public function testGroupOrganizationDeleteWithInvalidKey(): void {
     $paramsDelete = [
       'invalid_key' => 1,
     ];
diff --git a/tests/phpunit/api/v3/GroupTest.php b/tests/phpunit/api/v3/GroupTest.php
index c1a682563a89..aa2b47de6fd6 100644
--- a/tests/phpunit/api/v3/GroupTest.php
+++ b/tests/phpunit/api/v3/GroupTest.php
@@ -179,7 +179,7 @@ public function testGetGroupParamsWithGroupTitle($version) {
    * Test Group create with Group Type and Parent
    * FIXME: Api4
    */
-  public function testGroupCreateWithTypeAndParent() {
+  public function testGroupCreateWithTypeAndParent(): void {
     $params = [
       'name' => 'Test Group type',
       'title' => 'Test Group Type',
@@ -313,7 +313,7 @@ public function testgetfields($version) {
     $this->assertEquals('is_active', $result['values']['is_active']['name']);
   }
 
-  public function testIllegalParentsParams() {
+  public function testIllegalParentsParams(): void {
     $params = [
       'title' => 'Test illegal Group',
       'domain_id' => 1,
diff --git a/tests/phpunit/api/v3/ImTest.php b/tests/phpunit/api/v3/ImTest.php
index ec40b7d3b8e0..153d71f80801 100644
--- a/tests/phpunit/api/v3/ImTest.php
+++ b/tests/phpunit/api/v3/ImTest.php
@@ -100,7 +100,7 @@ public function testDeleteIm($version) {
   /**
    * Skip api4 test - delete behaves differently
    */
-  public function testDeleteImInvalid() {
+  public function testDeleteImInvalid(): void {
     $this->callAPISuccess(self::ENTITY, 'create', $this->params);
     $deleteParams = ['id' => 600];
     $this->callAPIFailure(self::ENTITY, 'delete', $deleteParams);
diff --git a/tests/phpunit/api/v3/JobProcessMailingTest.php b/tests/phpunit/api/v3/JobProcessMailingTest.php
index 24712ee8efbf..197d0408f53c 100644
--- a/tests/phpunit/api/v3/JobProcessMailingTest.php
+++ b/tests/phpunit/api/v3/JobProcessMailingTest.php
@@ -87,7 +87,7 @@ public function tearDown(): void {
     parent::tearDown();
   }
 
-  public function testBasic() {
+  public function testBasic(): void {
     $this->createContactsInGroup(10, $this->_groupID);
     Civi::settings()->add([
       'mailerBatchLimit' => 2,
@@ -103,7 +103,7 @@ public function testBasic() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testDeletedRecipient() {
+  public function testDeletedRecipient(): void {
     $this->createContactsInGroup(2, $this->_groupID);
     $this->callAPISuccess('Mailing', 'create', $this->_params);
     $this->callAPISuccess('Contact', 'delete', ['id' => $this->callAPISuccessGetValue('GroupContact', ['return' => 'contact_id', 'options' => ['limit' => 1, 'sort' => 'id DESC']])]);
@@ -114,7 +114,7 @@ public function testDeletedRecipient() {
   /**
    * Test what happens when a contact is set to decesaed
    */
-  public function testDeceasedRecipient() {
+  public function testDeceasedRecipient(): void {
     $contactID = $this->individualCreate(['first_name' => 'test dead recipeint', 'email' => 'mailtestdead@civicrm.org']);
     $this->callAPISuccess('group_contact', 'create', [
       'contact_id' => $contactID,
@@ -138,7 +138,7 @@ public function testDeceasedRecipient() {
   /**
    * Test that "multiple bulk email recipients" setting is respected.
    */
-  public function testMultipleBulkRecipients() {
+  public function testMultipleBulkRecipients(): void {
     Civi::settings()->add([
       'civimail_multiple_bulk_emails' => 1,
     ]);
@@ -213,7 +213,7 @@ public function testPauseAndResumeMailing(): void {
    * Test mail when in non-production environment.
    *
    */
-  public function testMailNonProductionRun() {
+  public function testMailNonProductionRun(): void {
     // Test in non-production mode.
     $params = [
       'environment' => 'Staging',
diff --git a/tests/phpunit/api/v3/JobProcessMembershipTest.php b/tests/phpunit/api/v3/JobProcessMembershipTest.php
index 96ddda6bcc1d..7e084bbd45b5 100644
--- a/tests/phpunit/api/v3/JobProcessMembershipTest.php
+++ b/tests/phpunit/api/v3/JobProcessMembershipTest.php
@@ -229,7 +229,7 @@ public function getMembershipStatus($membershipId) {
   /**
    * Test that by default test memberships are excluded.
    */
-  public function testByDefaultTestsAreExcluded() {
+  public function testByDefaultTestsAreExcluded(): void {
     $testId = $this->createTestMembershipThatShouldBeCurrent();
 
     $this->callAPISuccess('job', 'process_membership', []);
@@ -240,7 +240,7 @@ public function testByDefaultTestsAreExcluded() {
   /**
    * Test that by default memberships of inactive types are excluded.
    */
-  public function testByDefaultInactiveAreExcluded() {
+  public function testByDefaultInactiveAreExcluded(): void {
     $oldId = $this->createOldMembershipThatShouldBeCurrent();
 
     $this->callAPISuccess('job', 'process_membership', []);
@@ -251,7 +251,7 @@ public function testByDefaultInactiveAreExcluded() {
   /**
    * Test that by default grace memberships are considered.
    */
-  public function testByDefaultGraceIsConsidered() {
+  public function testByDefaultGraceIsConsidered(): void {
     $graceId = $this->createGraceMembershipThatShouldBeCurrent();
 
     $this->callAPISuccess('job', 'process_membership', []);
@@ -265,7 +265,7 @@ public function testByDefaultGraceIsConsidered() {
    * The pending status is still excluded as it's in the
    * exclude_membership_status_ids list by default.
    */
-  public function testByDefaultPendingIsExcluded() {
+  public function testByDefaultPendingIsExcluded(): void {
     $pendingId = $this->createPendingMembershipThatShouldBeCurrent();
 
     $this->callAPISuccess('job', 'process_membership', []);
@@ -276,7 +276,7 @@ public function testByDefaultPendingIsExcluded() {
   /**
    * Test that by default memberships of type deceased are excluded.
    */
-  public function testByDefaultDeceasedIsExcluded() {
+  public function testByDefaultDeceasedIsExcluded(): void {
     $deceasedId = $this->createDeceasedMembershipThatShouldBeExpired();
 
     $this->callAPISuccess('job', 'process_membership', []);
@@ -291,7 +291,7 @@ public function testByDefaultDeceasedIsExcluded() {
    * The pending status is still excluded as it's in the
    * exclude_membership_status_ids list by default.
    */
-  public function testIncludingTestMembershipsExcludesPending() {
+  public function testIncludingTestMembershipsExcludesPending(): void {
     $pendingId = $this->createPendingMembershipThatShouldBeCurrent();
 
     $this->callAPISuccess('job', 'process_membership', [
@@ -305,7 +305,7 @@ public function testIncludingTestMembershipsExcludesPending() {
    * Test that when including test memberships,
    * grace memberships are considered.
    */
-  public function testIncludingTestMembershipsConsidersGrace() {
+  public function testIncludingTestMembershipsConsidersGrace(): void {
     $graceId = $this->createGraceMembershipThatShouldBeCurrent();
 
     $this->callAPISuccess('job', 'process_membership', [
@@ -319,7 +319,7 @@ public function testIncludingTestMembershipsConsidersGrace() {
    * Test that when including test memberships,
    * memberships of inactive types are still ignored.
    */
-  public function testIncludingTestMembershipsIgnoresInactive() {
+  public function testIncludingTestMembershipsIgnoresInactive(): void {
     $oldId = $this->createOldMembershipThatShouldBeCurrent();
 
     $this->callAPISuccess('job', 'process_membership', [
@@ -333,7 +333,7 @@ public function testIncludingTestMembershipsIgnoresInactive() {
    * Test that when including test memberships,
    * acually includes test memberships.
    */
-  public function testIncludingTestMembershipsActuallyIncludesThem() {
+  public function testIncludingTestMembershipsActuallyIncludesThem(): void {
     $testId = $this->createTestMembershipThatShouldBeCurrent();
 
     $this->callAPISuccess('job', 'process_membership', [
@@ -347,7 +347,7 @@ public function testIncludingTestMembershipsActuallyIncludesThem() {
    * Test that when including test memberships,
    * memberships of type deceased are still ignored.
    */
-  public function testIncludingTestMembershipsStillIgnoresDeceased() {
+  public function testIncludingTestMembershipsStillIgnoresDeceased(): void {
     $deceasedId = $this->createDeceasedMembershipThatShouldBeExpired();
 
     $this->callAPISuccess('job', 'process_membership', [
@@ -364,7 +364,7 @@ public function testIncludingTestMembershipsStillIgnoresDeceased() {
    * The pending status is still excluded as it's in the
    * exclude_membership_status_ids list by default.
    */
-  public function testIncludingInactiveMembershipTypesStillExcludesPending() {
+  public function testIncludingInactiveMembershipTypesStillExcludesPending(): void {
     $pendingId = $this->createPendingMembershipThatShouldBeCurrent();
 
     $this->callAPISuccess('job', 'process_membership', [
@@ -378,7 +378,7 @@ public function testIncludingInactiveMembershipTypesStillExcludesPending() {
    * Test that when including inactive membership types,
    * grace memberships are considered.
    */
-  public function testIncludingInactiveMembershipTypesConsidersGrace() {
+  public function testIncludingInactiveMembershipTypesConsidersGrace(): void {
     $graceId = $this->createGraceMembershipThatShouldBeCurrent();
 
     $this->callAPISuccess('job', 'process_membership', [
@@ -392,7 +392,7 @@ public function testIncludingInactiveMembershipTypesConsidersGrace() {
    * Test that when including inactive membership types,
    * memberships of disabled membership types are considered.
    */
-  public function testIncludingInactiveMembershipTypesConsidersInactive() {
+  public function testIncludingInactiveMembershipTypesConsidersInactive(): void {
     $oldId = $this->createOldMembershipThatShouldBeCurrent();
 
     $this->callAPISuccess('job', 'process_membership', [
@@ -406,7 +406,7 @@ public function testIncludingInactiveMembershipTypesConsidersInactive() {
    * Test that when including inactive membership types,
    * test memberships are still ignored.
    */
-  public function testIncludingInactiveMembershipTypesStillIgnoresTests() {
+  public function testIncludingInactiveMembershipTypesStillIgnoresTests(): void {
     $testId = $this->createTestMembershipThatShouldBeCurrent();
 
     $this->callAPISuccess('job', 'process_membership', [
@@ -420,7 +420,7 @@ public function testIncludingInactiveMembershipTypesStillIgnoresTests() {
    * Test that when including inactive membership types,
    * memberships of type deceased are still ignored.
    */
-  public function testMembershipTypeDeceasedIsExcluded() {
+  public function testMembershipTypeDeceasedIsExcluded(): void {
     $deceasedId = $this->createDeceasedMembershipThatShouldBeExpired();
 
     $this->callAPISuccess('job', 'process_membership', [
@@ -434,7 +434,7 @@ public function testMembershipTypeDeceasedIsExcluded() {
    * Test that when explicitly setting the status ids to exclude,
    * memberships in deceased status are still ignored.
    */
-  public function testSpecifyingTheStatusIdsToExcludeStillExcludesDeceased() {
+  public function testSpecifyingTheStatusIdsToExcludeStillExcludesDeceased(): void {
     $deceasedId = $this->createDeceasedMembershipThatShouldBeExpired();
 
     $this->callAPISuccess('job', 'process_membership', [
@@ -450,7 +450,7 @@ public function testSpecifyingTheStatusIdsToExcludeStillExcludesDeceased() {
    * Test that when explicitly setting the status ids to exclude,
    * test memberships are still ignored.
    */
-  public function testSpecifyingTheStatusIdsToExcludeStillExcludesTests() {
+  public function testSpecifyingTheStatusIdsToExcludeStillExcludesTests(): void {
     $testId = $this->createTestMembershipThatShouldBeCurrent();
 
     $this->callAPISuccess('job', 'process_membership', [
@@ -466,7 +466,7 @@ public function testSpecifyingTheStatusIdsToExcludeStillExcludesTests() {
    * Test that when explicitly setting the status ids to exclude,
    * memberships of disabled membership types are still ignored.
    */
-  public function testSpecifyingTheStatusIdsToExcludeStillExcludesInactive() {
+  public function testSpecifyingTheStatusIdsToExcludeStillExcludesInactive(): void {
     $oldId = $this->createOldMembershipThatShouldBeCurrent();
 
     $this->callAPISuccess('job', 'process_membership', [
@@ -482,7 +482,7 @@ public function testSpecifyingTheStatusIdsToExcludeStillExcludesInactive() {
    * Test that when explicitly setting the status ids to exclude,
    * grace memberships are considered by default.
    */
-  public function testSpecifyingTheStatusIdsToExcludeGraceIsIncludedByDefault() {
+  public function testSpecifyingTheStatusIdsToExcludeGraceIsIncludedByDefault(): void {
     $graceId = $this->createGraceMembershipThatShouldBeCurrent();
 
     $this->callAPISuccess('job', 'process_membership', [
@@ -499,7 +499,7 @@ public function testSpecifyingTheStatusIdsToExcludeGraceIsIncludedByDefault() {
    * if the specified list doesn't include pending, then pending
    * memberships are considered.
    */
-  public function testSpecifyingTheStatusIdsToExcludePendingIsExcludedByDefault() {
+  public function testSpecifyingTheStatusIdsToExcludePendingIsExcludedByDefault(): void {
     $pendingId = $this->createPendingMembershipThatShouldBeCurrent();
 
     $this->callAPISuccess('job', 'process_membership', [
diff --git a/tests/phpunit/api/v3/JobTestCustomDataTest.php b/tests/phpunit/api/v3/JobTestCustomDataTest.php
index fa972463f2ab..aabc58c8fbc3 100644
--- a/tests/phpunit/api/v3/JobTestCustomDataTest.php
+++ b/tests/phpunit/api/v3/JobTestCustomDataTest.php
@@ -214,7 +214,7 @@ public function getCheckboxData() {
    *
    * Test CRM-18674 date custom field handling.
    */
-  public function testBatchMergeDateCustomFieldHandling() {
+  public function testBatchMergeDateCustomFieldHandling(): void {
     $customFieldLabel = 'custom_' . $this->customFieldID;
     $contactID = $this->individualCreate();
     $this->individualCreate([$customFieldLabel => '2012-12-03']);
@@ -229,7 +229,7 @@ public function testBatchMergeDateCustomFieldHandling() {
    *
    * Test CRM-18674 date custom field handling.
    */
-  public function testBatchMergeDateCustomFieldHandlingIsView() {
+  public function testBatchMergeDateCustomFieldHandlingIsView(): void {
     $this->customFieldCreate([
       'label' => 'OnlyView',
       'custom_group_id' => $this->customGroupID,
@@ -247,7 +247,7 @@ public function testBatchMergeDateCustomFieldHandlingIsView() {
   /**
    * Check we get a conflict on the custom field.
    */
-  public function testBatchMergeDateCustomFieldConflict() {
+  public function testBatchMergeDateCustomFieldConflict(): void {
     $customFieldLabel = 'custom_' . $this->customFieldID;
     $contactID = $this->individualCreate([$customFieldLabel => '2012-11-03']);
     $this->individualCreate([$customFieldLabel => '2013-11-03']);
@@ -261,7 +261,7 @@ public function testBatchMergeDateCustomFieldConflict() {
   /**
    * Check we get a conflict on the custom field.
    */
-  public function testBatchMergeDateCustomFieldNoConflict() {
+  public function testBatchMergeDateCustomFieldNoConflict(): void {
     $customFieldLabel = 'custom_' . $this->customFieldID;
     $contactID = $this->individualCreate([$customFieldLabel => '2012-11-03']);
     $this->individualCreate([$customFieldLabel => '2012-11-03']);
@@ -275,7 +275,7 @@ public function testBatchMergeDateCustomFieldNoConflict() {
   /**
    * Check we get a no conflict on the custom field & integer merges.
    */
-  public function testBatchMergeIntCustomFieldNoConflict() {
+  public function testBatchMergeIntCustomFieldNoConflict(): void {
     $customFieldLabel = 'custom_' . $this->customIntFieldID;
     $contactID = $this->individualCreate([]);
     $this->individualCreate([$customFieldLabel => 20]);
@@ -289,7 +289,7 @@ public function testBatchMergeIntCustomFieldNoConflict() {
   /**
    * Check we get a conflict on the integer custom field.
    */
-  public function testBatchMergeIntCustomFieldConflict() {
+  public function testBatchMergeIntCustomFieldConflict(): void {
     $customFieldLabel = 'custom_' . $this->customIntFieldID;
     $contactID = $this->individualCreate([$customFieldLabel => 20]);
     $this->individualCreate([$customFieldLabel => 1]);
@@ -303,7 +303,7 @@ public function testBatchMergeIntCustomFieldConflict() {
   /**
    * Check we get a conflict on the integer custom field when the conflicted field is 0.
    */
-  public function testBatchMergeIntCustomFieldConflictZero() {
+  public function testBatchMergeIntCustomFieldConflictZero(): void {
     $customFieldLabel = 'custom_' . $this->customIntFieldID;
     $contactID = $this->individualCreate([$customFieldLabel => 0]);
     $this->individualCreate([$customFieldLabel => 20]);
@@ -319,7 +319,7 @@ public function testBatchMergeIntCustomFieldConflictZero() {
    *
    * Test CRM-18674 date custom field handling.
    */
-  public function testBatchMergeDateCustomFieldConflictAndNoCheckPerms() {
+  public function testBatchMergeDateCustomFieldConflictAndNoCheckPerms(): void {
     CRM_Core_Config::singleton()->userPermissionClass->permissions = ['access CiviCRM', 'edit my contact'];
     CRM_Core_DAO::executeQuery("DELETE FROM civicrm_cache");
     CRM_Utils_System::flushCache();
@@ -338,7 +338,7 @@ public function testBatchMergeDateCustomFieldConflictAndNoCheckPerms() {
    *
    * Test CRM-18674 date custom field handling.
    */
-  public function testBatchMergeDateCustomFieldNoConflictAndNoCheckPerms() {
+  public function testBatchMergeDateCustomFieldNoConflictAndNoCheckPerms(): void {
     CRM_Core_Config::singleton()->userPermissionClass->permissions = ['access CiviCRM', 'edit my contact'];
     CRM_Core_DAO::executeQuery("DELETE FROM civicrm_cache");
     CRM_Utils_System::flushCache();
@@ -357,7 +357,7 @@ public function testBatchMergeDateCustomFieldNoConflictAndNoCheckPerms() {
    *
    * Test CRM-19113 custom data lost when permissions in play.
    */
-  public function testBatchMergeIntCustomFieldNoConflictAndNoCheckPerms() {
+  public function testBatchMergeIntCustomFieldNoConflictAndNoCheckPerms(): void {
     CRM_Core_Config::singleton()->userPermissionClass->permissions = ['access CiviCRM', 'edit my contact'];
     CRM_Core_DAO::executeQuery("DELETE FROM civicrm_cache");
     CRM_Utils_System::flushCache();
@@ -378,7 +378,7 @@ public function testBatchMergeIntCustomFieldNoConflictAndNoCheckPerms() {
   /**
    * Check we get a conflict on the customs field when the data conflicts for booleans.
    */
-  public function testBatchMergeCustomFieldConflicts() {
+  public function testBatchMergeCustomFieldConflicts(): void {
     $this->individualCreate(['custom_' . $this->customBoolFieldID => 0]);
     $this->individualCreate(['custom_' . $this->customBoolFieldID => 1]);
     $result = $this->callAPISuccess('Job', 'process_batch_merge', []);
@@ -389,7 +389,7 @@ public function testBatchMergeCustomFieldConflicts() {
   /**
    * Check we get a conflict on the customs field when the data conflicts for booleans (reverse).
    */
-  public function testBatchMergeCustomFieldConflictsReverse() {
+  public function testBatchMergeCustomFieldConflictsReverse(): void {
     $this->individualCreate(['custom_' . $this->customBoolFieldID => 1]);
     $this->individualCreate(['custom_' . $this->customBoolFieldID => 0]);
     $result = $this->callAPISuccess('Job', 'process_batch_merge', []);
@@ -402,7 +402,7 @@ public function testBatchMergeCustomFieldConflictsReverse() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testBatchMergeCustomFieldNoConflictsOneBlank() {
+  public function testBatchMergeCustomFieldNoConflictsOneBlank(): void {
     $this->individualCreate(['custom_' . $this->customBoolFieldID => 1]);
     $this->individualCreate();
     $result = $this->callAPISuccess('Job', 'process_batch_merge', []);
@@ -415,7 +415,7 @@ public function testBatchMergeCustomFieldNoConflictsOneBlank() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testBatchMergeCustomFieldNoConflictsOneBlankReverse() {
+  public function testBatchMergeCustomFieldNoConflictsOneBlankReverse(): void {
     $contactID = $this->individualCreate();
     $this->individualCreate(['custom_' . $this->customBoolFieldID => 1]);
     $result = $this->callAPISuccess('Job', 'process_batch_merge', []);
diff --git a/tests/phpunit/api/v3/LocBlockTest.php b/tests/phpunit/api/v3/LocBlockTest.php
index 127c60419eb0..f45e2fc1249c 100644
--- a/tests/phpunit/api/v3/LocBlockTest.php
+++ b/tests/phpunit/api/v3/LocBlockTest.php
@@ -31,7 +31,7 @@ public function setUp(): void {
   /**
    * Test creating location block.
    */
-  public function testCreateLocBlock() {
+  public function testCreateLocBlock(): void {
     $email = $this->callAPISuccess('email', 'create', [
       'contact_id' => 'null',
       'email' => 'test@loc.block',
@@ -61,7 +61,7 @@ public function testCreateLocBlock() {
   /**
    * Test creating location block entities.
    */
-  public function testCreateLocBlockEntities() {
+  public function testCreateLocBlockEntities(): void {
     $params = [
       'email' => [
         'location_type_id' => 1,
diff --git a/tests/phpunit/api/v3/LoggingTest.php b/tests/phpunit/api/v3/LoggingTest.php
index a72649969d8c..6dfadcfbd1e1 100644
--- a/tests/phpunit/api/v3/LoggingTest.php
+++ b/tests/phpunit/api/v3/LoggingTest.php
@@ -72,7 +72,7 @@ public function testEnableDisableLogging(): void {
   /**
    * Test that logging is successfully enabled and disabled.
    */
-  public function testEnableDisableLoggingWithTriggerHook() {
+  public function testEnableDisableLoggingWithTriggerHook(): void {
     $this->hookClass->setHook('civicrm_alterLogTables', [$this, 'innodbLogTableSpec']);
     $this->callAPISuccess('Setting', 'create', ['logging' => TRUE]);
     $this->checkINNODBLogTableCreated();
@@ -92,7 +92,7 @@ public function testEnableDisableLoggingWithTriggerHook() {
    *
    * The settings for unique id will not be set.
    */
-  public function testEnableLoggingLegacyLogTableExists() {
+  public function testEnableLoggingLegacyLogTableExists(): void {
     $this->createLegacyStyleContactLogTable();
     $this->callAPISuccess('Setting', 'create', ['logging' => TRUE]);
     $this->checkTriggersCreated(FALSE);
@@ -103,7 +103,7 @@ public function testEnableLoggingLegacyLogTableExists() {
   /**
    * Check we can update legacy log tables using the api function.
    */
-  public function testUpdateLegacyLogTable() {
+  public function testUpdateLegacyLogTable(): void {
     $this->createLegacyStyleContactLogTable();
     $this->callAPISuccess('Setting', 'create', ['logging' => TRUE]);
     $this->callAPISuccess('System', 'updatelogtables', []);
@@ -119,7 +119,7 @@ public function testUpdateLegacyLogTable() {
   /**
    * Check if we can create missing log tables using api.
    */
-  public function testCreateMissingLogTables() {
+  public function testCreateMissingLogTables(): void {
     $this->callAPISuccess('Setting', 'create', ['logging' => TRUE]);
     CRM_Core_DAO::executeQuery("DROP TABLE log_civicrm_contact");
     $this->callAPISuccess('System', 'createmissinglogtables', []);
@@ -131,7 +131,7 @@ public function testCreateMissingLogTables() {
   /**
    * Check we can update legacy log tables using the api function.
    */
-  public function testUpdateLogTableHookINNODB() {
+  public function testUpdateLogTableHookINNODB(): void {
     $this->createLegacyStyleContactLogTable();
     $this->callAPISuccess('Setting', 'create', ['logging' => TRUE]);
     $this->hookClass->setHook('civicrm_alterLogTables', [$this, 'innodbLogTableSpec']);
@@ -287,7 +287,7 @@ protected function createLegacyStyleContactLogTable() {
   /**
    * Test changes can be reverted.
    */
-  public function testRevert() {
+  public function testRevert(): void {
     $contactId = $this->individualCreate();
     $this->callAPISuccess('Setting', 'create', ['logging' => TRUE]);
     // Pause for one second here to ensure the timestamps between the first create action
@@ -309,7 +309,7 @@ public function testRevert() {
   /**
    * Test changes can be reverted.
    */
-  public function testRevertNoDate() {
+  public function testRevertNoDate(): void {
     $contactId = $this->individualCreate();
     $this->callAPISuccess('Setting', 'create', ['logging' => TRUE]);
     // Pause for one second here to ensure the timestamps between the first create action
@@ -335,7 +335,7 @@ public function testRevertNoDate() {
    *
    * @throws \Exception
    */
-  public function testRevertRestrictedTables() {
+  public function testRevertRestrictedTables(): void {
 
     CRM_Core_DAO::executeQuery("SET @uniqueID = 'temp name'");
     $this->callAPISuccess('Setting', 'create', ['logging' => TRUE]);
@@ -380,7 +380,7 @@ public function testRevertRestrictedTables() {
   /**
    * Test changes can be reverted.
    */
-  public function testRevertNoDateNotUnique() {
+  public function testRevertNoDateNotUnique(): void {
     $contactId = $this->individualCreate();
     $this->callAPISuccess('Setting', 'create', ['logging' => TRUE]);
     CRM_Core_DAO::executeQuery("SET @uniqueID = 'Wopity woot'");
@@ -402,7 +402,7 @@ public function testRevertNoDateNotUnique() {
   /**
    * Test changes can be retrieved.
    */
-  public function testGet() {
+  public function testGet(): void {
     $contactId = $this->individualCreate();
     $this->callAPISuccess('Setting', 'create', ['logging' => TRUE]);
     CRM_Core_DAO::executeQuery("SET @uniqueID = 'wooty woot'");
@@ -425,7 +425,7 @@ public function testGet() {
   /**
    * Test changes can be retrieved without log_date being required.
    */
-  public function testGetNoDate() {
+  public function testGetNoDate(): void {
     $contactId = $this->individualCreate();
     $this->callAPISuccess('Setting', 'create', ['logging' => TRUE]);
     CRM_Core_DAO::executeQuery("SET @uniqueID = 'wooty wop wop'");
diff --git a/tests/phpunit/api/v3/MailingABTest.php b/tests/phpunit/api/v3/MailingABTest.php
index 22026fd026a3..a4cb2061f20b 100644
--- a/tests/phpunit/api/v3/MailingABTest.php
+++ b/tests/phpunit/api/v3/MailingABTest.php
@@ -70,7 +70,7 @@ public function setUp(): void {
   /**
    * Test civicrm_mailing_create.
    */
-  public function testMailingABCreateSuccess() {
+  public function testMailingABCreateSuccess(): void {
     $result = $this->callAPISuccess($this->_entity, 'create', $this->_params);
     $this->assertTrue(is_numeric($result['id']), "In line " . __LINE__);
     $this->assertEquals($this->_params['group_percentage'], $result['values'][$result['id']]['group_percentage']);
@@ -79,7 +79,7 @@ public function testMailingABCreateSuccess() {
   /**
    * Test civicrm_mailing_delete.
    */
-  public function testMailerDeleteSuccess() {
+  public function testMailerDeleteSuccess(): void {
     $result = $this->callAPISuccess($this->_entity, 'create', $this->_params);
 
     $this->assertDBQuery(1, "SELECT count(*) FROM civicrm_mailing_abtest WHERE id = %1", [
@@ -167,7 +167,7 @@ public function testDistribution($totalGroupContacts, $groupPct, $expectedCountA
    * Create a test. Declare the second mailing a winner. Ensure that key
    * fields propagate to the final mailing.
    */
-  public function testSubmitWinnderId() {
+  public function testSubmitWinnderId(): void {
     $checkSyncFields = ['subject', 'body_text'];
 
     $result = $this->groupContactCreate($this->_groupID, 20, TRUE);
diff --git a/tests/phpunit/api/v3/MailingContactTest.php b/tests/phpunit/api/v3/MailingContactTest.php
index f9e72752a71b..443e193fa857 100644
--- a/tests/phpunit/api/v3/MailingContactTest.php
+++ b/tests/phpunit/api/v3/MailingContactTest.php
@@ -41,7 +41,7 @@ public function tearDown(): void {
     parent::tearDown();
   }
 
-  public function testMailingContactGetFields() {
+  public function testMailingContactGetFields(): void {
     $result = $this->callAPISuccess('MailingContact', 'getfields', [
       'action' => 'get',
     ]);
@@ -56,7 +56,7 @@ public function testMailingContactGetFields() {
    * Test is of marginal if any value & testing of wrapper level functionality
    * belongs in the SyntaxConformance class
    */
-  public function testMailingNoContactID() {
+  public function testMailingNoContactID(): void {
     $this->callAPIFailure('MailingContact', 'get', ['something' => 'This is not a real field']);
   }
 
@@ -68,14 +68,14 @@ public function testMailingNoContactID() {
    * Test is of marginal if any value & testing of wrapper level functionality
    * belongs in the SyntaxConformance class
    */
-  public function testMailingContactInvalidContactID() {
+  public function testMailingContactInvalidContactID(): void {
     $this->callAPIFailure('MailingContact', 'get', ['contact_id' => 'This is not a number']);
   }
 
   /**
    * Test that invalid types are returned with appropriate errors.
    */
-  public function testMailingContactInvalidType() {
+  public function testMailingContactInvalidType(): void {
     $params = [
       'contact_id' => 23,
       'type' => 'invalid',
@@ -86,7 +86,7 @@ public function testMailingContactInvalidType() {
   /**
    * Test for success result when there are no mailings for a the given contact.
    */
-  public function testMailingContactNoMailings() {
+  public function testMailingContactNoMailings(): void {
     $params = [
       'contact_id' => $this->contact['id'],
     ];
@@ -98,7 +98,7 @@ public function testMailingContactNoMailings() {
   /**
    * Test that the API returns a mailing properly when there is only one.
    */
-  public function testMailingContactDelivered() {
+  public function testMailingContactDelivered(): void {
     list($contactID, $mailingID, $eventQueueID) = $this->setupEventQueue();
     CRM_Core_DAO::executeQuery("INSERT INTO civicrm_mailing_event_delivered (event_queue_id) VALUES(%1)", [1 => [$eventQueueID, 'Integer']]);
 
@@ -123,7 +123,7 @@ public function testMailingContactDelivered() {
    *
    * @throws \Exception
    */
-  public function testMailingContactBounced() {
+  public function testMailingContactBounced(): void {
     list($contactID, $mailingID, $eventQueueID) = $this->setupEventQueue();
     CRM_Core_DAO::executeQuery("INSERT INTO civicrm_mailing_event_bounce (event_queue_id, bounce_type_id) VALUES(%1, 6)", [1 => [$eventQueueID, 'Integer']]);
 
diff --git a/tests/phpunit/api/v3/MailingTest.php b/tests/phpunit/api/v3/MailingTest.php
index 9f503c9cfd62..bc1d419e7dbe 100644
--- a/tests/phpunit/api/v3/MailingTest.php
+++ b/tests/phpunit/api/v3/MailingTest.php
@@ -98,7 +98,7 @@ public function testMailerCreateSuccess(int $version): void {
   /**
    * Tes that the parameter _skip_evil_bao_auto_schedule_ is respected & prevents jobs being created.
    */
-  public function testSkipAutoSchedule() {
+  public function testSkipAutoSchedule(): void {
     $this->callAPISuccess('Mailing', 'create', array_merge($this->_params, [
       '_skip_evil_bao_auto_schedule_' => TRUE,
       'scheduled_date' => 'now',
@@ -139,7 +139,7 @@ public function testMailerCreateSuccessNoCreatedID(): void {
   /**
    *
    */
-  public function testTemplateTypeOptions() {
+  public function testTemplateTypeOptions(): void {
     $types = $this->callAPISuccess('Mailing', 'getoptions', ['field' => 'template_type']);
     $this->assertTrue(isset($types['values']['traditional']));
   }
@@ -147,7 +147,7 @@ public function testTemplateTypeOptions() {
   /**
    * Check that default header+footer are available.
    */
-  public function testHeaderFooterOptions() {
+  public function testHeaderFooterOptions(): void {
     $headers = $this->callAPISuccess('Mailing', 'getoptions', ['field' => 'header']);
     $this->assertTrue(in_array('Mailing Header', $headers['values']));
     $footers = $this->callAPISuccess('Mailing', 'getoptions', ['field' => 'footer']);
@@ -161,7 +161,7 @@ public function testHeaderFooterOptions() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testMailerCreateTemplateOptions() {
+  public function testMailerCreateTemplateOptions(): void {
     // 1. Create mailing with template_options.
     $params = $this->_params;
     $params['template_options'] = json_encode(['foo' => 'bar_1']);
@@ -200,7 +200,7 @@ public function testMailerCreateTemplateOptions() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testMagicGroups_create_update() {
+  public function testMagicGroups_create_update(): void {
     // BEGIN SAMPLE DATA
     $groupIDs['a'] = $this->groupCreate(['name' => 'Example include group', 'title' => 'Example include group']);
     $groupIDs['b'] = $this->groupCreate(['name' => 'Example exclude group', 'title' => 'Example exclude group']);
@@ -391,7 +391,7 @@ public function testMailerPreviewRecipients(): void {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testMailerPreviewRecipientsDeduplicateAndOnholdEmails() {
+  public function testMailerPreviewRecipientsDeduplicateAndOnholdEmails(): void {
     // BEGIN SAMPLE DATA
     $groupIDs['grp'] = $this->groupCreate(['name' => 'Example group', 'title' => 'Example group']);
     $contactIDs['include_me'] = $this->individualCreate([
@@ -460,7 +460,7 @@ public function testMailerPreviewRecipientsDeduplicateAndOnholdEmails() {
   /**
    * Test sending a test mailing.
    */
-  public function testMailerSendTest_email() {
+  public function testMailerSendTest_email(): void {
     $contactIDs['alice'] = $this->individualCreate([
       'email' => 'alice@example.org',
       'first_name' => 'Alice',
@@ -487,7 +487,7 @@ public function testMailerSendTest_email() {
   /**
    *
    */
-  public function testMailerSendTest_group() {
+  public function testMailerSendTest_group(): void {
     // BEGIN SAMPLE DATA
     $groupIDs['inc'] = $this->groupCreate(['name' => 'Example include group', 'title' => 'Example include group']);
     $contactIDs['alice'] = $this->individualCreate([
@@ -697,7 +697,7 @@ public function testMailerSubmit($useLogin, array $createParams, $submitParams,
    *
    * @throws \CRM_Core_Exception
    */
-  public function testUnsubscribeGroupList() {
+  public function testUnsubscribeGroupList(): void {
     // Create set of groups and add a contact to both of them.
     $groupID2 = $this->groupCreate(['name' => 'Test group 2', 'title' => 'group title 2']);
     $groupID3 = $this->groupCreate(['name' => 'Test group 3', 'title' => 'group title 3']);
@@ -768,7 +768,7 @@ public function testUnsubscribeGroupList() {
   /**
    *
    */
-  public function testMailerStats() {
+  public function testMailerStats(): void {
     $result = $this->groupContactCreate($this->_groupID, 100);
     //verify if 100 contacts are added for group
     $this->assertEquals(100, $result['added']);
@@ -822,7 +822,7 @@ public function testMailerStats() {
   /**
    * Test civicrm_mailing_delete.
    */
-  public function testMailerDeleteSuccess() {
+  public function testMailerDeleteSuccess(): void {
     $result = $this->callAPISuccess($this->_entity, 'create', $this->_params);
     $this->callAPISuccess($this->_entity, 'delete', ['id' => $result['id']]);
     $this->assertAPIDeleted($this->_entity, $result['id']);
@@ -831,7 +831,7 @@ public function testMailerDeleteSuccess() {
   /**
    * Test Mailing.gettokens.
    */
-  public function testMailGetTokens() {
+  public function testMailGetTokens(): void {
     $result = $this->callAPISuccess($this->_entity, 'gettokens', ['entity' => ['Contact', 'Mailing']]);
     $this->assertContains('Contact Type', $result['values']);
 
@@ -846,7 +846,7 @@ public function testMailGetTokens() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testClone() {
+  public function testClone(): void {
     // BEGIN SAMPLE DATA
     $groupIDs['inc'] = $this->groupCreate(['name' => 'Example include group', 'title' => 'Example include group']);
     $contactIDs['include_me'] = $this->individualCreate([
@@ -901,7 +901,7 @@ public function testClone() {
    * api function cannot be considered supported  / 'part of the api' without a
    * success test
    */
-  public function testMailerBounceWrongParams() {
+  public function testMailerBounceWrongParams(): void {
     $params = [
       'job_id' => 'Wrong ID',
       'event_queue_id' => 'Wrong ID',
@@ -922,7 +922,7 @@ public function testMailerBounceWrongParams() {
    * api function cannot be considered supported  / 'part of the api' without a
    * success test
    */
-  public function testMailerConfirmWrongParams() {
+  public function testMailerConfirmWrongParams(): void {
     $params = [
       'contact_id' => 'Wrong ID',
       'subscribe_id' => 'Wrong ID',
@@ -944,7 +944,7 @@ public function testMailerConfirmWrongParams() {
    * api function cannot be considered supported  / 'part of the api' without a
    * success test
    */
-  public function testMailerReplyWrongParams() {
+  public function testMailerReplyWrongParams(): void {
     $params = [
       'job_id' => 'Wrong ID',
       'event_queue_id' => 'Wrong ID',
@@ -966,7 +966,7 @@ public function testMailerReplyWrongParams() {
    * api function cannot be considered supported  / 'part of the api' without a
    * success test
    */
-  public function testMailerForwardWrongParams() {
+  public function testMailerForwardWrongParams(): void {
     $params = [
       'job_id' => 'Wrong ID',
       'event_queue_id' => 'Wrong ID',
@@ -1002,7 +1002,7 @@ public function createDraftMailing($params = []) {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testUrlWithMissingTrackingHash() {
+  public function testUrlWithMissingTrackingHash(): void {
     $mail = $this->callAPISuccess('mailing', 'create', $this->_params + ['scheduled_date' => 'now'], __FUNCTION__, __FILE__);
     $jobs = $this->callAPISuccess('mailing_job', 'get', ['mailing_id' => $mail['id']]);
     $this->assertEquals(1, $jobs['count']);
@@ -1036,7 +1036,7 @@ public function testUrlWithMissingTrackingHash() {
   /**
    * Test Trackable URL with unicode character
    */
-  public function testTrackableURLWithUnicodeSign() {
+  public function testTrackableURLWithUnicodeSign(): void {
     $unicodeURL = "https://civińcrm.org";
     $this->_params['body_text'] = str_replace("https://civicrm.org", $unicodeURL, $this->_params['body_text']);
     $this->_params['body_html'] = str_replace("https://civicrm.org", $unicodeURL, $this->_params['body_html']);
@@ -1069,7 +1069,7 @@ public function testTrackableURLWithUnicodeSign() {
    * CRM-20892 : Test if Mail.create API throws error on update,
    *  if modified_date less then the date when the mail was last updated/created
    */
-  public function testModifiedDateMismatchOnMailingUpdate() {
+  public function testModifiedDateMismatchOnMailingUpdate(): void {
     $mail = $this->callAPISuccess('mailing', 'create', $this->_params + ['modified_date' => 'now']);
     try {
       $this->callAPISuccess('mailing', 'create', $this->_params + ['id' => $mail['id'], 'modified_date' => '2 seconds ago']);
@@ -1084,7 +1084,7 @@ public function testModifiedDateMismatchOnMailingUpdate() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testUpdateEmailResetdate() {
+  public function testUpdateEmailResetdate(): void {
     $this->callAPISuccess('Mailing', 'update_email_resetdate', []);
   }
 
diff --git a/tests/phpunit/api/v3/MappingFieldTest.php b/tests/phpunit/api/v3/MappingFieldTest.php
index 1bf9b4ad0472..6e6d6f45c26b 100644
--- a/tests/phpunit/api/v3/MappingFieldTest.php
+++ b/tests/phpunit/api/v3/MappingFieldTest.php
@@ -38,14 +38,14 @@ public function setUp(): void {
     ];
   }
 
-  public function testCreateMappingField() {
+  public function testCreateMappingField(): void {
     $result = $this->callAPISuccess($this->_entity, 'create', $this->params);
     $this->assertEquals(1, $result['count']);
     $this->getAndCheck($this->params, $result['id'], $this->_entity);
     $this->assertNotNull($result['values'][$result['id']]['id']);
   }
 
-  public function testGetMappingField() {
+  public function testGetMappingField(): void {
     $result = $this->callAPISuccess($this->_entity, 'create', $this->params);
     $result = $this->callAPISuccess($this->_entity, 'get', $this->params);
     $this->assertEquals(1, $result['count']);
@@ -53,7 +53,7 @@ public function testGetMappingField() {
     $this->callAPISuccess($this->_entity, 'delete', ['id' => $result['id']]);
   }
 
-  public function testDeleteMappingField() {
+  public function testDeleteMappingField(): void {
     $result = $this->callAPISuccess($this->_entity, 'create', $this->params);
     $deleteParams = ['id' => $result['id']];
     $result = $this->callAPISuccess($this->_entity, 'delete', $deleteParams);
@@ -61,7 +61,7 @@ public function testDeleteMappingField() {
     $this->assertEquals(0, $checkDeleted['count']);
   }
 
-  public function testDeleteMappingFieldInvalid() {
+  public function testDeleteMappingFieldInvalid(): void {
     $result = $this->callAPISuccess($this->_entity, 'create', $this->params);
     $deleteParams = ['id' => 600];
     $result = $this->callAPIFailure($this->_entity, 'delete', $deleteParams);
diff --git a/tests/phpunit/api/v3/MembershipPaymentTest.php b/tests/phpunit/api/v3/MembershipPaymentTest.php
index 9f073b2745f7..1fada13a5a1f 100644
--- a/tests/phpunit/api/v3/MembershipPaymentTest.php
+++ b/tests/phpunit/api/v3/MembershipPaymentTest.php
@@ -66,14 +66,14 @@ public function setUp(): void {
   /**
    * Test civicrm_membership_payment_create with empty params.
    */
-  public function testCreateEmptyParams() {
+  public function testCreateEmptyParams(): void {
     $this->callAPIFailure('membership_payment', 'create', [], 'Mandatory key(s) missing from params array: membership_id, contribution_id');
   }
 
   /**
    * Test civicrm_membership_payment_create - success expected.
    */
-  public function testCreate() {
+  public function testCreate(): void {
     $contactId = $this->individualCreate();
 
     $params = [
@@ -104,7 +104,7 @@ public function testCreate() {
   /**
    * Test civicrm_membershipPayment_get - success expected.
    */
-  public function testGet() {
+  public function testGet(): void {
     $contactId = $this->individualCreate();
     $params = [
       'contact_id' => $contactId,
diff --git a/tests/phpunit/api/v3/MembershipStatusTest.php b/tests/phpunit/api/v3/MembershipStatusTest.php
index 7868b8df2e56..3e7fd52170a9 100644
--- a/tests/phpunit/api/v3/MembershipStatusTest.php
+++ b/tests/phpunit/api/v3/MembershipStatusTest.php
@@ -46,7 +46,7 @@ public function tearDown(): void {
   /**
    * Test civicrm_membership_status_get with empty params.
    */
-  public function testGetEmptyParams() {
+  public function testGetEmptyParams(): void {
     $result = $this->callAPISuccess('membership_status', 'get', []);
     // It should be 8 statuses, 7 default from mysql_data
     // plus one test status added in setUp
@@ -56,7 +56,7 @@ public function testGetEmptyParams() {
   /**
    * Test civicrm_membership_status_get. Success expected.
    */
-  public function testGet() {
+  public function testGet(): void {
     $params = [
       'name' => 'test status',
     ];
@@ -67,7 +67,7 @@ public function testGet() {
   /**
    * Test civicrm_membership_status_get. Success expected.
    */
-  public function testGetLimit() {
+  public function testGetLimit(): void {
     $result = $this->callAPISuccess('membership_status', 'get', []);
     $this->assertGreaterThan(1, $result['count'], "Check more than one exists In line " . __LINE__);
     $params['option.limit'] = 1;
@@ -88,7 +88,7 @@ public function testCreateWithMissingRequired(): void {
     $this->callAPIFailure('MembershipStatus', 'create', $params, 'Mandatory key(s) missing from params array: name');
   }
 
-  public function testCreate() {
+  public function testCreate(): void {
     $params = [
       'name' => 'test membership status',
     ];
@@ -98,7 +98,7 @@ public function testCreate() {
     $this->membershipStatusDelete($result['id']);
   }
 
-  public function testUpdate() {
+  public function testUpdate(): void {
     $params = [
       'name' => 'test membership status',
     ];
@@ -124,12 +124,12 @@ public function testDeleteEmptyParams(): void {
     $this->callAPIFailure('membership_status', 'delete', []);
   }
 
-  public function testDeleteWithMissingRequired() {
+  public function testDeleteWithMissingRequired(): void {
     $params = ['title' => 'Does not make sense'];
     $result = $this->callAPIFailure('membership_status', 'delete', $params);
   }
 
-  public function testDelete() {
+  public function testDelete(): void {
     $membershipID = $this->membershipStatusCreate();
     $params = [
       'id' => $membershipID,
@@ -140,7 +140,7 @@ public function testDelete() {
   /**
    * Test that after checking the person as 'Deceased', the Membership is also 'Deceased' both through inline and normal edit.
    */
-  public function testDeceasedMembershipInline() {
+  public function testDeceasedMembershipInline(): void {
     $contactID = $this->individualCreate();
     $params = [
       'contact_id' => $contactID,
diff --git a/tests/phpunit/api/v3/MembershipTest.php b/tests/phpunit/api/v3/MembershipTest.php
index 6a51f8b1bac8..e6d04ffcc9c3 100644
--- a/tests/phpunit/api/v3/MembershipTest.php
+++ b/tests/phpunit/api/v3/MembershipTest.php
@@ -106,18 +106,18 @@ public function testMembershipDelete(): void {
     $this->assertDBRowNotExist('CRM_Member_DAO_Membership', $membershipID);
   }
 
-  public function testMembershipDeleteEmpty() {
+  public function testMembershipDeleteEmpty(): void {
     $this->callAPIFailure('membership', 'delete', []);
   }
 
-  public function testMembershipDeleteInvalidID() {
+  public function testMembershipDeleteInvalidID(): void {
     $this->callAPIFailure('membership', 'delete', ['id' => 'blah']);
   }
 
   /**
    * Test membership deletion and with the preserve contribution param.
    */
-  public function testMembershipDeletePreserveContribution() {
+  public function testMembershipDeletePreserveContribution(): void {
     //DELETE
     $membershipID = $this->contactMembershipCreate($this->_params);
     //DELETE
@@ -236,7 +236,7 @@ public function testMultipleMembershipsContribution(): void {
   /**
    * Test membership get.
    */
-  public function testContactMembershipsGet() {
+  public function testContactMembershipsGet(): void {
     $this->_membershipID = $this->contactMembershipCreate($this->_params);
     $this->callAPISuccess('membership', 'get', []);
     $this->callAPISuccess('Membership', 'Delete', ['id' => $this->_membershipID]);
@@ -247,7 +247,7 @@ public function testContactMembershipsGet() {
    *
    * Gets treated as contact_id, memberships expected.
    */
-  public function testGetWithParamsContactId() {
+  public function testGetWithParamsContactId(): void {
     $this->_membershipID = $this->contactMembershipCreate($this->_params);
     $params = [
       'contact_id' => $this->_contactID,
@@ -295,7 +295,7 @@ public function testGetInSyntax(): void {
    * Test civicrm_membership_get with params not array.
    * Gets treated as contact_id, memberships expected.
    */
-  public function testGetInSyntaxOnContactID() {
+  public function testGetInSyntaxOnContactID(): void {
     $this->_membershipID = $this->contactMembershipCreate($this->_params);
     $contact2 = $this->individualCreate();
     $contact3 = $this->individualCreate(['first_name' => 'Scout', 'last_name' => 'Canine']);
@@ -343,7 +343,7 @@ public function testGetWithParamsMemberShipTypeId(): void {
    * Test civicrm_membership_get with params not array.
    * Gets treated as contact_id, memberships expected.
    */
-  public function testGetWithParamsMemberShipTypeIdContactID() {
+  public function testGetWithParamsMemberShipTypeIdContactID(): void {
     $params = $this->_params;
     $this->callAPISuccess($this->_entity, 'create', $params);
     $params['membership_type_id'] = $this->_membershipTypeID2;
@@ -389,7 +389,7 @@ public function testGetWithParamsMemberShipIdAndCustom(): void {
    * Test civicrm_membership_get with proper params.
    * Memberships expected.
    */
-  public function testGet() {
+  public function testGet(): void {
     $this->contactMembershipCreate($this->_params);
     $params = [
       'contact_id' => $this->_contactID,
@@ -412,7 +412,7 @@ public function testGet() {
    * Test civicrm_membership_get with proper params.
    * Memberships expected.
    */
-  public function testGetWithId() {
+  public function testGetWithId(): void {
     $membershipID = $this->contactMembershipCreate($this->_params);
     $params = [
       'contact_id' => $this->_contactID,
@@ -434,7 +434,7 @@ public function testGetWithId() {
    * Test civicrm_membership_get for only active.
    * Memberships expected.
    */
-  public function testGetOnlyActive() {
+  public function testGetOnlyActive(): void {
     $this->_membershipID = $this->contactMembershipCreate($this->_params);
     $params = [
       'contact_id' => $this->_contactID,
@@ -462,7 +462,7 @@ public function testGetOnlyActive() {
    * Test civicrm_membership_get for non exist contact.
    * empty Memberships.
    */
-  public function testGetNoContactExists() {
+  public function testGetNoContactExists(): void {
     $params = [
       'contact_id' => 55555,
     ];
@@ -477,7 +477,7 @@ public function testGetNoContactExists() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testGetWithRelationship() {
+  public function testGetWithRelationship(): void {
     $membershipOrgId = $this->organizationCreate();
     $memberContactId = $this->individualCreate();
 
@@ -545,7 +545,7 @@ public function testGetWithRelationship() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testCreateWithRelationship() {
+  public function testCreateWithRelationship(): void {
     // Create membership type: inherited through employment, max_related = 2
     $params = [
       'name_a_b' => 'Employee of',
@@ -724,7 +724,7 @@ public function testCreateWithRelationship() {
    * @throws \CRM_Core_Exception
    * @throws \Civi\API\Exception\UnauthorizedException
    */
-  public function testCreateWithSpouseRelationship() {
+  public function testCreateWithSpouseRelationship(): void {
     $relationshipTypeID = RelationshipType::get()->addSelect('id')->addWhere('name_a_b', '=', 'Spouse of')->execute()->first()['id'];
     MembershipType::update()->setValues([
       'relationship_direction' => ['b_a', 'a_b'],
@@ -788,7 +788,7 @@ public function testCreateWithSpouseRelationship() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testMembershipGetWithReturn() {
+  public function testMembershipGetWithReturn(): void {
     $this->contactMembershipCreate($this->_params);
     $result = $this->callAPISuccess('membership', 'get', ['return' => 'end_date']);
     foreach ($result['values'] as $membership) {
@@ -831,13 +831,13 @@ public function testCreatePendingWithSkipStatusCalc(): void {
   /**
    * If is_overide is passed in status must also be passed in.
    */
-  public function testCreateOverrideNoStatus() {
+  public function testCreateOverrideNoStatus(): void {
     $params = $this->_params;
     unset($params['status_id']);
     $this->callAPIFailure('membership', 'create', $params);
   }
 
-  public function testMembershipCreateMissingRequired() {
+  public function testMembershipCreateMissingRequired(): void {
     $params = [
       'membership_type_id' => '1',
       'join_date' => '2006-01-21',
@@ -850,7 +850,7 @@ public function testMembershipCreateMissingRequired() {
     $this->callAPIFailure('membership', 'create', $params);
   }
 
-  public function testMembershipCreate() {
+  public function testMembershipCreate(): void {
     $params = [
       'contact_id' => $this->_contactID,
       'membership_type_id' => $this->getMembershipTypeID('General'),
@@ -895,7 +895,7 @@ public function testMembershipCreateWithInvalidContact(): void {
    * variables specific to participant so it can be replicated into other entities
    * and / or moved to the automated test suite
    */
-  public function testCreateWithCustom() {
+  public function testCreateWithCustom(): void {
     $ids = $this->entityCustomGroupWithSingleFieldCreate(__FUNCTION__, __FILE__);
 
     $params = $this->_params;
@@ -974,7 +974,7 @@ public function testMembershipCreateWithId($version): void {
    * membership).
    * success expected.
    */
-  public function testMembershipCreateUpdateWithIdNoContact() {
+  public function testMembershipCreateUpdateWithIdNoContact(): void {
     $membershipID = $this->contactMembershipCreate($this->_params);
     $params = [
       'id' => $membershipID,
@@ -1001,7 +1001,7 @@ public function testMembershipCreateUpdateWithIdNoContact() {
    * membership).
    * success expected.
    */
-  public function testMembershipCreateUpdateWithIdNoDates() {
+  public function testMembershipCreateUpdateWithIdNoDates(): void {
     $membershipID = $this->contactMembershipCreate($this->_params);
     $params = [
       'id' => $membershipID,
@@ -1024,7 +1024,7 @@ public function testMembershipCreateUpdateWithIdNoDates() {
    * membership).
    * success expected.
    */
-  public function testMembershipCreateUpdateWithIdNoDatesNoType() {
+  public function testMembershipCreateUpdateWithIdNoDatesNoType(): void {
     $membershipID = $this->contactMembershipCreate($this->_params);
     $params = [
       'id' => $membershipID,
@@ -1046,7 +1046,7 @@ public function testMembershipCreateUpdateWithIdNoDatesNoType() {
    * membership).
    * success expected.
    */
-  public function testMembershipCreateUpdateWithIDAndSource() {
+  public function testMembershipCreateUpdateWithIDAndSource(): void {
     $membershipID = $this->contactMembershipCreate($this->_params);
     $params = [
       'id' => $membershipID,
@@ -1066,7 +1066,7 @@ public function testMembershipCreateUpdateWithIDAndSource() {
   /**
    * Change custom field using update.
    */
-  public function testUpdateWithCustom() {
+  public function testUpdateWithCustom(): void {
     $ids = $this->entityCustomGroupWithSingleFieldCreate(__FUNCTION__, __FILE__);
 
     $params = $this->_params;
@@ -1093,7 +1093,7 @@ public function testUpdateWithCustom() {
   /**
    * per CRM-15746 check that the id can be altered in an update hook
    */
-  public function testMembershipUpdateCreateHookCRM15746() {
+  public function testMembershipUpdateCreateHookCRM15746(): void {
     $this->hookClass->setHook('civicrm_pre', [$this, 'hook_civicrm_pre_update_create_membership']);
     $result = $this->callAPISuccess('membership', 'create', $this->_params);
     $this->callAPISuccess('membership', 'create', ['id' => $result['id'], 'end_date' => '1 year ago']);
@@ -1127,7 +1127,7 @@ public function hook_civicrm_pre_update_create_membership($op, $objectName, $id,
    * Test civicrm_contact_memberships_create Invalid membership data.
    * Error expected.
    */
-  public function testMembershipCreateInvalidMemData() {
+  public function testMembershipCreateInvalidMemData(): void {
     //membership_contact_id as string
     $params = [
       'membership_contact_id' => 'Invalid',
@@ -1157,7 +1157,7 @@ public function testMembershipCreateInvalidMemData() {
    * membership).
    * Success expected.
    */
-  public function testMembershipCreateWithMemContact() {
+  public function testMembershipCreateWithMemContact(): void {
     $params = [
       'membership_contact_id' => $this->_contactID,
       'membership_type_id' => $this->_membershipTypeID,
@@ -1202,7 +1202,7 @@ public function testMembershipCreateValidMembershipTypeString(): void {
    * membership).
    * Success expected.
    */
-  public function testMembershipCreateInValidMembershipTypeString() {
+  public function testMembershipCreateInValidMembershipTypeString(): void {
     $params = [
       'membership_contact_id' => $this->_contactID,
       'membership_type_id' => 'invalid',
@@ -1220,7 +1220,7 @@ public function testMembershipCreateInValidMembershipTypeString() {
   /**
    * Test that if membership join date is not set it defaults to today.
    */
-  public function testEmptyJoinDate() {
+  public function testEmptyJoinDate(): void {
     unset($this->_params['join_date'], $this->_params['is_override']);
     $result = $this->callAPISuccess($this->_entity, 'create', $this->_params);
     $result = $this->callAPISuccess($this->_entity, 'getsingle', ['id' => $result['id']]);
@@ -1233,7 +1233,7 @@ public function testEmptyJoinDate() {
    * Test that if membership start date is not set it defaults to correct end date.
    *  - fixed
    */
-  public function testEmptyStartDateFixed() {
+  public function testEmptyStartDateFixed(): void {
     unset($this->_params['start_date'], $this->_params['is_override']);
     $this->_params['membership_type_id'] = $this->_membershipTypeID2;
     $result = $this->callAPISuccess($this->_entity, 'create', $this->_params);
@@ -1247,7 +1247,7 @@ public function testEmptyStartDateFixed() {
    * Test that if membership start date is not set it defaults to correct end date
    *  - fixed
    */
-  public function testEmptyStartEndDateFixedOneYear() {
+  public function testEmptyStartEndDateFixedOneYear(): void {
     unset($this->_params['start_date'], $this->_params['is_override'], $this->_params['end_date']);
     $this->callAPISuccess('membership_type', 'create', ['id' => $this->_membershipTypeID2, 'duration_interval' => 1]);
     $this->_params['membership_type_id'] = $this->_membershipTypeID2;
@@ -1261,7 +1261,7 @@ public function testEmptyStartEndDateFixedOneYear() {
   /**
    * Test that if membership start date is not set it defaults to correct end date for fixed multi year memberships.
    */
-  public function testEmptyStartEndDateFixedMultiYear() {
+  public function testEmptyStartEndDateFixedMultiYear(): void {
     unset($this->_params['start_date'], $this->_params['is_override'], $this->_params['end_date']);
     $this->callAPISuccess('membership_type', 'create', ['id' => $this->_membershipTypeID2, 'duration_interval' => 5]);
     $this->_params['membership_type_id'] = $this->_membershipTypeID2;
@@ -1277,7 +1277,7 @@ public function testEmptyStartEndDateFixedMultiYear() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testMembershipJoinDateFixed() {
+  public function testMembershipJoinDateFixed(): void {
     $memStatus = CRM_Member_PseudoConstant::membershipStatus();
     // Update the fixed membership type to 1 year duration.
     $this->callAPISuccess('membership_type', 'create', ['id' => $this->_membershipTypeID2, 'duration_interval' => 1]);
@@ -1342,7 +1342,7 @@ public function testMembershipJoinDateFixed() {
    * and we end one day before the rollover day. Start day is 1 Jan so we end on 31 Dec
    * and we add on 4 years rather than 5 because we are not after the rollover day - so we calculate 31 Dec 2019
    */
-  public function testFixedMultiYearDateSetTwoEmptyStartEndDate() {
+  public function testFixedMultiYearDateSetTwoEmptyStartEndDate(): void {
     unset($this->_params['start_date'], $this->_params['is_override'], $this->_params['end_date']);
 
     $this->callAPISuccess('membership_type', 'create', [
@@ -1371,7 +1371,7 @@ public function testFixedMultiYearDateSetTwoEmptyStartEndDate() {
    * and we end one day before the rollover day. Start day is 1 Jan so we end on 31 Dec
    * and we add on 4 years rather than 5 because we are not after the rollover day - so we calculate 31 Dec 2019
    */
-  public function testFixedMultiYearDateSetTwoEmptyEndDate() {
+  public function testFixedMultiYearDateSetTwoEmptyEndDate(): void {
     unset($this->_params['start_date'], $this->_params['is_override'], $this->_params['end_date']);
 
     $this->callAPISuccess('membership_type', 'create', [
@@ -1403,7 +1403,7 @@ public function testFixedMultiYearDateSetTwoEmptyEndDate() {
    * and we end one day before the rollover day. Start day is 1 Jan so we end on 31 Dec
    * and we add on <1 years rather than > 1 because we are not after the rollover day - so we calculate 31 Dec 2015
    */
-  public function testFixedSingleYearDateSetTwoEmptyStartEndDate() {
+  public function testFixedSingleYearDateSetTwoEmptyStartEndDate(): void {
     unset($this->_params['start_date'], $this->_params['is_override'], $this->_params['end_date']);
 
     $this->callAPISuccess('membership_type', 'create', [
@@ -1432,7 +1432,7 @@ public function testFixedSingleYearDateSetTwoEmptyStartEndDate() {
    * and we end one day before the rollover day. Start day is 1 Jan so we end on 31 Dec
    * and we add on <1 years rather than > 1 because we are not after the rollover day - so we calculate 31 Dec 2015
    */
-  public function testFixedSingleYearDateSetTwoEmptyEndDate() {
+  public function testFixedSingleYearDateSetTwoEmptyEndDate(): void {
     unset($this->_params['start_date'], $this->_params['is_override'], $this->_params['end_date']);
 
     $this->callAPISuccess('membership_type', 'create', [
@@ -1462,7 +1462,7 @@ public function testFixedSingleYearDateSetTwoEmptyEndDate() {
    * and we end one day before the rollover day. Start day is 1 Nov so we end on 31 Oct
    * and we add on 1 year we are after the rollover day - so we calculate 31 Oct 2016
    */
-  public function testFixedSingleYearDateSetThreeEmptyEndDate() {
+  public function testFixedSingleYearDateSetThreeEmptyEndDate(): void {
     unset($this->_params['start_date'], $this->_params['is_override'], $this->_params['end_date']);
 
     $this->callAPISuccess('membership_type', 'create', [
@@ -1494,7 +1494,7 @@ public function testFixedSingleYearDateSetThreeEmptyEndDate() {
    * and we end one day before the rollover day. Start day is 1 Nov so we end on 31 Oct
    * and we add on 1 year we are after the rollover day - so we calculate 31 Oct 2016
    */
-  public function testFixedSingleYearDateSetThreeEmptyStartEndDate() {
+  public function testFixedSingleYearDateSetThreeEmptyStartEndDate(): void {
     unset($this->_params['start_date'], $this->_params['is_override'], $this->_params['end_date']);
 
     $this->callAPISuccess('membership_type', 'create', [
@@ -1523,7 +1523,7 @@ public function testFixedSingleYearDateSetThreeEmptyStartEndDate() {
    * and we end one day before the rollover day. Start day is 1 Nov so we end on 31 Oct
    * and we add on 5 years we are after the rollover day - so we calculate 31 Oct 2020
    */
-  public function testFixedMultiYearDateSetThreeEmptyEndDate() {
+  public function testFixedMultiYearDateSetThreeEmptyEndDate(): void {
     unset($this->_params['start_date'], $this->_params['is_override'], $this->_params['end_date']);
 
     $this->callAPISuccess('membership_type', 'create', [
@@ -1556,7 +1556,7 @@ public function testFixedMultiYearDateSetThreeEmptyEndDate() {
    * and we end one day before the rollover day. Start day is 1 Nov so we end on 31 Oct
    * and we add on 5 years we are after the rollover day - so we calculate 31 Oct 2020
    */
-  public function testFixedMultiYearDateSetThreeEmptyStartEndDate() {
+  public function testFixedMultiYearDateSetThreeEmptyStartEndDate(): void {
     unset($this->_params['start_date'], $this->_params['is_override'], $this->_params['end_date']);
 
     $this->callAPISuccess('membership_type', 'create', [
@@ -1581,7 +1581,7 @@ public function testFixedMultiYearDateSetThreeEmptyStartEndDate() {
   /**
    * Test that if membership start date is not set it defaults to correct end date for fixed single year memberships.
    */
-  public function testEmptyStartDateRolling() {
+  public function testEmptyStartDateRolling(): void {
     unset($this->_params['start_date'], $this->_params['is_override']);
     $result = $this->callAPISuccess($this->_entity, 'create', $this->_params);
     $result = $this->callAPISuccess($this->_entity, 'getsingle', ['id' => $result['id']]);
@@ -1594,7 +1594,7 @@ public function testEmptyStartDateRolling() {
    * Test that if membership end date is not set it defaults to correct end date.
    *  - rolling
    */
-  public function testEmptyEndDateFixed() {
+  public function testEmptyEndDateFixed(): void {
     unset($this->_params['start_date'], $this->_params['is_override'], $this->_params['end_date']);
     $this->_params['membership_type_id'] = $this->_membershipTypeID2;
     $result = $this->callAPISuccess($this->_entity, 'create', $this->_params);
@@ -1608,7 +1608,7 @@ public function testEmptyEndDateFixed() {
    * Test that if membership end date is not set it defaults to correct end date.
    *  - rolling
    */
-  public function testEmptyEndDateRolling() {
+  public function testEmptyEndDateRolling(): void {
     unset($this->_params['is_override'], $this->_params['end_date']);
     $this->_params['membership_type_id'] = $this->_membershipTypeID;
     $result = $this->callAPISuccess($this->_entity, 'create', $this->_params);
@@ -1621,7 +1621,7 @@ public function testEmptyEndDateRolling() {
   /**
    * Test that if dates are set they not over-ridden if id is passed in
    */
-  public function testMembershipDatesNotOverridden() {
+  public function testMembershipDatesNotOverridden(): void {
     $result = $this->callAPISuccess($this->_entity, 'create', $this->_params);
     unset($this->_params['end_date'], $this->_params['start_date']);
     $this->_params['id'] = $result['id'];
@@ -1638,7 +1638,7 @@ public function testMembershipDatesNotOverridden() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testMultipleMembershipContribution() {
+  public function testMultipleMembershipContribution(): void {
     $this->createMultipleMembershipOrder();
     $this->callAPISuccess('Payment', 'create', [
       'contribution_id' => $this->ids['Contribution'][0],
@@ -1658,7 +1658,7 @@ public function testMultipleMembershipContribution() {
    *
    * See CRM-17075.
    */
-  public function testGetOptionsMembershipTypeID() {
+  public function testGetOptionsMembershipTypeID(): void {
     $options = $this->callAPISuccess('Membership', 'getoptions', ['field' => 'membership_type_id']);
     $this->assertEquals('Another one', array_pop($options['values']));
     $this->assertEquals('General', array_pop($options['values']));
diff --git a/tests/phpunit/api/v3/MultilingualTest.php b/tests/phpunit/api/v3/MultilingualTest.php
index 4186da2f9334..c55c5ef152a1 100644
--- a/tests/phpunit/api/v3/MultilingualTest.php
+++ b/tests/phpunit/api/v3/MultilingualTest.php
@@ -79,7 +79,7 @@ public function testOptionLanguage($version) {
    * CRM-19677: Ensure that entity apis are not affected on Multilingual setup
    *  with check_permissions = TRUE
    */
-  public function testAllEntities() {
+  public function testAllEntities(): void {
     $this->enableMultilingual();
 
     // list of entities which has mandatory attributes
diff --git a/tests/phpunit/api/v3/NavigationTest.php b/tests/phpunit/api/v3/NavigationTest.php
index 647b7f5cc6bd..ba9296d7f3a2 100644
--- a/tests/phpunit/api/v3/NavigationTest.php
+++ b/tests/phpunit/api/v3/NavigationTest.php
@@ -33,7 +33,7 @@ public function testGet($version) {
    * Test get specifying parent
    * FIXME: Api4
    */
-  public function testGetByParent() {
+  public function testGetByParent(): void {
     // get by name
     $this->callAPISuccess($this->_entity, 'get', ['parentID' => 'Administer', 'domain_id' => 1]);
 
diff --git a/tests/phpunit/api/v3/NoteTest.php b/tests/phpunit/api/v3/NoteTest.php
index c63f29b10f59..dd378efa2e2a 100644
--- a/tests/phpunit/api/v3/NoteTest.php
+++ b/tests/phpunit/api/v3/NoteTest.php
@@ -269,7 +269,7 @@ public function testUpdate($version) {
    *
    * Error expected.
    */
-  public function testDeleteWithEmptyParams() {
+  public function testDeleteWithEmptyParams(): void {
     $this->callAPIFailure('note', 'delete', [], 'Mandatory key(s) missing from params array: id');
   }
 
@@ -304,7 +304,7 @@ public function testDelete($version) {
     $this->callAPISuccess('note', 'delete', $params);
   }
 
-  public function testNoteJoin() {
+  public function testNoteJoin(): void {
     $org = $this->callAPISuccess('Contact', 'create', [
       'contact_type' => 'Organization',
       'organization_name' => 'Org123',
diff --git a/tests/phpunit/api/v3/OptionGroupTest.php b/tests/phpunit/api/v3/OptionGroupTest.php
index 9974967dc289..1f9eaf63a920 100644
--- a/tests/phpunit/api/v3/OptionGroupTest.php
+++ b/tests/phpunit/api/v3/OptionGroupTest.php
@@ -33,41 +33,41 @@ public function setUp(): void {
   /**
    * Good to test option group as a representative on the Camel Case.
    */
-  public function testGetOptionGroupGetFields() {
+  public function testGetOptionGroupGetFields(): void {
     $result = $this->callAPISuccess('option_group', 'getfields', []);
     $this->assertFalse(empty($result['values']));
   }
 
-  public function testGetOptionGroupGetFieldsCreateAction() {
+  public function testGetOptionGroupGetFieldsCreateAction(): void {
     $result = $this->callAPISuccess('option_group', 'getfields', ['action' => 'create']);
     $this->assertFalse(empty($result['values']));
     $this->assertEquals($result['values']['name']['api.unique'], 1);
   }
 
-  public function testGetOptionGroupByID() {
+  public function testGetOptionGroupByID(): void {
     $result = $this->callAPISuccess('option_group', 'get', ['id' => 1]);
     $this->assertEquals(1, $result['count']);
     $this->assertEquals(1, $result['id']);
   }
 
-  public function testGetOptionGroupByName() {
+  public function testGetOptionGroupByName(): void {
     $params = ['name' => 'preferred_communication_method'];
     $result = $this->callAPISuccess('option_group', 'get', $params);
     $this->assertEquals(1, $result['count']);
     $this->assertEquals(1, $result['id']);
   }
 
-  public function testGetOptionGroup() {
+  public function testGetOptionGroup(): void {
     $result = $this->callAPISuccess('option_group', 'get', []);
     $this->assertGreaterThan(1, $result['count']);
   }
 
-  public function testGetOptionDoesNotExist() {
+  public function testGetOptionDoesNotExist(): void {
     $result = $this->callAPISuccess('option_group', 'get', ['name' => 'FSIGUBSFGOMUUBSFGMOOUUBSFGMOOBUFSGMOOIIB']);
     $this->assertEquals(0, $result['count']);
   }
 
-  public function testGetOptionCreateSuccess() {
+  public function testGetOptionCreateSuccess(): void {
     $params = [
       'sequential' => 1,
       'name' => 'civicrm_event.amount.560',
@@ -91,7 +91,7 @@ public function testGetOptionCreateSuccess() {
   /**
    * Test the error message when a failure is due to a key duplication issue.
    */
-  public function testGetOptionCreateFailOnDuplicate() {
+  public function testGetOptionCreateFailOnDuplicate(): void {
     $params = [
       'sequential' => 1,
       'name' => 'civicrm_dup_entry',
@@ -108,7 +108,7 @@ public function testGetOptionCreateFailOnDuplicate() {
    *
    * Check error returned.
    */
-  public function testGetOptionCreateFailRollback() {
+  public function testGetOptionCreateFailRollback(): void {
     $countFirst = $this->callAPISuccess('OptionGroup', 'getcount', ['options' => ['limit' => 5000]]);
     $params = [
       'sequential' => 1,
@@ -137,7 +137,7 @@ public function testGetOptionCreateFailRollback() {
   /**
    * Success test for updating an existing Option Group.
    */
-  public function testCreateUpdateOptionGroup() {
+  public function testCreateUpdateOptionGroup(): void {
     $result = $this->callAPISuccess($this->_entity, 'create', $this->_params);
     $params = array_merge($this->_params, ['id' => $result['id'], 'is_active' => 0]);
     $this->callAPISuccess($this->_entity, 'create', $params);
@@ -147,7 +147,7 @@ public function testCreateUpdateOptionGroup() {
   /**
    * Success test for deleting an existing Option Group.
    */
-  public function testDeleteOptionGroup() {
+  public function testDeleteOptionGroup(): void {
     $result = $this->callAPISuccess($this->_entity, 'create', $this->_params);
     $this->callAPISuccess('OptionGroup', 'delete', ['id' => $result['id']]);
   }
@@ -157,7 +157,7 @@ public function testDeleteOptionGroup() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testEnsureOptionGroupExistsExistingValue() {
+  public function testEnsureOptionGroupExistsExistingValue(): void {
     CRM_Core_BAO_OptionGroup::ensureOptionGroupExists(['name' => 'participant_role']);
     $this->callAPISuccessGetSingle('OptionGroup', ['name' => 'participant_role']);
   }
@@ -165,7 +165,7 @@ public function testEnsureOptionGroupExistsExistingValue() {
   /**
    * Ensure only one option value exists adds a new value.
    */
-  public function testEnsureOptionGroupExistsNewValue() {
+  public function testEnsureOptionGroupExistsNewValue(): void {
     $optionGroupID = CRM_Core_BAO_OptionGroup::ensureOptionGroupExists([
       'name' => 'Bombed',
       'title' => ts('Catastrophy'),
diff --git a/tests/phpunit/api/v3/OptionValueTest.php b/tests/phpunit/api/v3/OptionValueTest.php
index 4b29ad0b66fe..7303e965ec23 100644
--- a/tests/phpunit/api/v3/OptionValueTest.php
+++ b/tests/phpunit/api/v3/OptionValueTest.php
@@ -21,18 +21,18 @@ public function setUp(): void {
     $this->useTransaction(TRUE);
   }
 
-  public function testGetCount() {
+  public function testGetCount(): void {
     $result = $this->callAPISuccess('option_value', 'getcount', []);
     $this->assertGreaterThan(100, $result);
   }
 
-  public function testGetOptionValueByID() {
+  public function testGetOptionValueByID(): void {
     $result = $this->callAPISuccess('option_value', 'get', ['id' => 1]);
     $this->assertEquals(1, $result['count']);
     $this->assertEquals(1, $result['id']);
   }
 
-  public function testGetOptionValueByValue() {
+  public function testGetOptionValueByValue(): void {
     $result = $this->callAPISuccess('option_value', 'get', ['option_group_id' => 1, 'value' => '1']);
     $this->assertEquals(1, $result['count']);
     $this->assertEquals(1, $result['id']);
@@ -41,7 +41,7 @@ public function testGetOptionValueByValue() {
   /**
    * Test limit param.
    */
-  public function testGetOptionValueLimit() {
+  public function testGetOptionValueLimit(): void {
     $params = [];
     $result = $this->callAPISuccess('option_value', 'get', $params);
     $this->assertGreaterThan(1, $result['count'], "Check more than one exists In line " . __LINE__);
@@ -53,7 +53,7 @@ public function testGetOptionValueLimit() {
   /**
    * Test offset param.
    */
-  public function testGetOptionValueOffSet() {
+  public function testGetOptionValueOffSet(): void {
 
     $result = $this->callAPISuccess('option_value', 'get', [
       'option_group_id' => 1,
@@ -70,7 +70,7 @@ public function testGetOptionValueOffSet() {
   /**
    * Test offset param.
    */
-  public function testGetSingleValueOptionValueSort() {
+  public function testGetSingleValueOptionValueSort(): void {
     $result = $this->callAPISuccess('option_value', 'getsingle', [
       'option_group_id' => 1,
       'options' => [
@@ -92,7 +92,7 @@ public function testGetSingleValueOptionValueSort() {
   /**
    * Try to emulate a pagination: fetch the first page of 10 options, then fetch the second page with an offset of 9 (instead of 10) and check the start of the second page is the end of the 1st one.
    */
-  public function testGetValueOptionPagination() {
+  public function testGetValueOptionPagination(): void {
     $pageSize = 10;
     $page1 = $this->callAPISuccess('option_value', 'get', ['options' => ['limit' => $pageSize]]);
     $page2 = $this->callAPISuccess('option_value', 'get', [
@@ -111,7 +111,7 @@ public function testGetValueOptionPagination() {
     $this->assertEquals($first, $last, "the first item of the second page should be the last of the 1st page" . __LINE__);
   }
 
-  public function testGetOptionGroup() {
+  public function testGetOptionGroup(): void {
     $params = ['option_group_id' => 1];
     $result = $this->callAPISuccess('option_value', 'get', $params);
     $this->assertGreaterThan(1, $result['count']);
@@ -120,7 +120,7 @@ public function testGetOptionGroup() {
   /**
    * Test that using option_group_name returns more than 1 & less than all
    */
-  public function testGetOptionGroupByName() {
+  public function testGetOptionGroupByName(): void {
     $activityTypesParams = ['option_group_name' => 'activity_type', 'option.limit' => 100];
     $params = ['option.limit' => 100];
     $activityTypes = $this->callAPISuccess('option_value', 'get', $activityTypesParams);
@@ -129,7 +129,7 @@ public function testGetOptionGroupByName() {
     $this->assertGreaterThan($activityTypes['count'], $result['count']);
   }
 
-  public function testGetOptionDoesNotExist() {
+  public function testGetOptionDoesNotExist(): void {
     $result = $this->callAPISuccess('option_value', 'get', ['label' => 'FSIGUBSFGOMUUBSFGMOOUUBSFGMOOBUFSGMOOIIB']);
     $this->assertEquals(0, $result['count']);
   }
@@ -137,7 +137,7 @@ public function testGetOptionDoesNotExist() {
   /**
    * Check that domain_id is honoured.
    */
-  public function testCreateOptionSpecifyDomain() {
+  public function testCreateOptionSpecifyDomain(): void {
     $result = $this->callAPISuccess('option_group', 'get', [
       'name' => 'from_email_address',
       'sequential' => 1,
@@ -156,7 +156,7 @@ public function testCreateOptionSpecifyDomain() {
   /**
    * Check that component_id is honoured.
    */
-  public function testCreateOptionSpecifyComponentID() {
+  public function testCreateOptionSpecifyComponentID(): void {
     $result = $this->callAPISuccess('option_group', 'get', [
       'name' => 'from_email_address',
       'sequential' => 1,
@@ -175,7 +175,7 @@ public function testCreateOptionSpecifyComponentID() {
   /**
    * Check that component string is honoured.
    */
-  public function testCreateOptionSpecifyComponentString() {
+  public function testCreateOptionSpecifyComponentString(): void {
     $result = $this->callAPISuccess('option_group', 'get', [
       'name' => 'from_email_address',
       'sequential' => 1,
@@ -197,7 +197,7 @@ public function testCreateOptionSpecifyComponentString() {
   /**
    * Check that component is honoured when fetching options.
    */
-  public function testGetOptionWithComponent() {
+  public function testGetOptionWithComponent(): void {
     $components = Civi::settings()->get('enable_components');
     CRM_Core_BAO_ConfigSetting::enableComponent('CiviContribute');
     $this->callAPISuccess('option_group', 'get', [
@@ -247,7 +247,7 @@ public function testGetOptionWithComponent() {
   /**
    * Check that domain_id is honoured.
    */
-  public function testCRM12133CreateOptionWeightNoValue() {
+  public function testCRM12133CreateOptionWeightNoValue(): void {
     $optionGroup = $this->callAPISuccess(
       'option_group', 'get', [
         'name' => 'gender',
@@ -276,7 +276,7 @@ public function testCRM12133CreateOptionWeightNoValue() {
   /**
    * Check that domain_id is honoured.
    */
-  public function testCreateOptionNoName() {
+  public function testCreateOptionNoName(): void {
     $optionGroup = $this->callAPISuccess('option_group', 'get', [
       'name' => 'gender',
       'sequential' => 1,
@@ -315,7 +315,7 @@ public function testCRM11876CreateOptionPseudoConstantUpdated(): void {
    * Update option value with 'id' parameter and the value to update
    * and not passing option group id
    */
-  public function testUpdateOptionValueNoGroupId() {
+  public function testUpdateOptionValueNoGroupId(): void {
     // create a option group
     $og = $this->callAPISuccess('option_group', 'create', ['name' => 'our test Option Group', 'is_active' => 1]);
     // create a option value
@@ -335,7 +335,7 @@ public function testUpdateOptionValueNoGroupId() {
    * Update option value with 'id' parameter and the value to update
    * and as well as option group id
    */
-  public function testUpdateOptionValueWithGroupId() {
+  public function testUpdateOptionValueWithGroupId(): void {
     // create a option group
     $og = $this->callAPISuccess('option_group', 'create', [
       'name' => 'our test Option Group for with group id',
@@ -361,7 +361,7 @@ public function testUpdateOptionValueWithGroupId() {
   /**
    * CRM-19346 Ensure that Option Values cannot share same value in the same option value group
    */
-  public function testCreateOptionValueWithSameValue() {
+  public function testCreateOptionValueWithSameValue(): void {
     $og = $this->callAPISuccess('option_group', 'create', [
       'name' => 'our test Option Group for with group id',
       'is_active' => 1,
@@ -379,7 +379,7 @@ public function testCreateOptionValueWithSameValue() {
   /**
    * CRM-21737 Ensure that language Option Values CAN share same value.
    */
-  public function testCreateOptionValueWithSameValueLanguagesException() {
+  public function testCreateOptionValueWithSameValueLanguagesException(): void {
     $this->callAPISuccess('option_value', 'create',
       ['option_group_id' => 'languages', 'label' => 'Quasi English', 'name' => 'en_Qu', 'value' => 'en']
     );
@@ -389,7 +389,7 @@ public function testCreateOptionValueWithSameValueLanguagesException() {
 
   }
 
-  public function testCreateOptionValueWithSameValueDiffOptionGroup() {
+  public function testCreateOptionValueWithSameValueDiffOptionGroup(): void {
     $og = $this->callAPISuccess('option_group', 'create', [
       'name' => 'our test Option Group',
       'is_active' => 1,
@@ -411,7 +411,7 @@ public function testCreateOptionValueWithSameValueDiffOptionGroup() {
   /**
    * Test to create and update payment method with financial account.
    */
-  public function testCreateUpdateOptionValueForPaymentInstrument() {
+  public function testCreateUpdateOptionValueForPaymentInstrument(): void {
     $assetFinancialAccountId = $this->callAPISuccessGetValue('FinancialAccount', [
       'return' => "id",
       'financial_account_type_id' => "Asset",
diff --git a/tests/phpunit/api/v3/ParticipantStatusTypeTest.php b/tests/phpunit/api/v3/ParticipantStatusTypeTest.php
index a7c652972558..2e27bfc94e70 100644
--- a/tests/phpunit/api/v3/ParticipantStatusTypeTest.php
+++ b/tests/phpunit/api/v3/ParticipantStatusTypeTest.php
@@ -34,13 +34,13 @@ public function setUp(): void {
     $this->useTransaction(TRUE);
   }
 
-  public function testCreateParticipantStatusType() {
+  public function testCreateParticipantStatusType(): void {
     $result = $this->callAPISuccess('participant_status_type', 'create', $this->params);
     $this->assertEquals(1, $result['count']);
     $this->assertNotNull($result['values'][$result['id']]['id']);
   }
 
-  public function testGetParticipantStatusType() {
+  public function testGetParticipantStatusType(): void {
     $result = $this->callAPISuccess('participant_status_type', 'create', $this->params);
     $this->assertEquals(1, $result['count']);
 
@@ -50,7 +50,7 @@ public function testGetParticipantStatusType() {
     $this->id = $result['id'];
   }
 
-  public function testDeleteParticipantStatusType() {
+  public function testDeleteParticipantStatusType(): void {
 
     $ParticipantStatusType = $this->callAPISuccess('ParticipantStatusType', 'Create', $this->params);
     $entity = $this->callAPISuccess('participant_status_type', 'get', []);
diff --git a/tests/phpunit/api/v3/PhoneTest.php b/tests/phpunit/api/v3/PhoneTest.php
index fb8cbdffcca2..bd9c7cdb395e 100644
--- a/tests/phpunit/api/v3/PhoneTest.php
+++ b/tests/phpunit/api/v3/PhoneTest.php
@@ -111,7 +111,7 @@ public function testGetEmptyParams($version) {
   /**
    * Test civicrm_phone_get with wrong params.
    */
-  public function testGetWrongParams() {
+  public function testGetWrongParams(): void {
     $this->callAPIFailure('Phone', 'Get', ['contact_id' => 'abc']);
     $this->callAPIFailure('Phone', 'Get', ['location_type_id' => 'abc']);
     $this->callAPIFailure('Phone', 'Get', ['phone_type_id' => 'abc']);
diff --git a/tests/phpunit/api/v3/PledgeTest.php b/tests/phpunit/api/v3/PledgeTest.php
index 5ea29c126160..d5eb5f262dc0 100644
--- a/tests/phpunit/api/v3/PledgeTest.php
+++ b/tests/phpunit/api/v3/PledgeTest.php
@@ -63,7 +63,7 @@ public function tearDown(): void {
    * variables specific to participant so it can be replicated into other entities
    * and / or moved to the automated test suite
    */
-  public function testCreateWithCustom() {
+  public function testCreateWithCustom(): void {
     $ids = $this->entityCustomGroupWithSingleFieldCreate(__FUNCTION__, __FILE__);
 
     $params = $this->_params;
@@ -84,7 +84,7 @@ public function testCreateWithCustom() {
   /**
    * Test getfields function for pledge.
    */
-  public function testGetfieldsPledge() {
+  public function testGetfieldsPledge(): void {
     $result = $this->callAPISuccess('pledge', 'getfields', ['action' => 'get']);
     $this->assertEquals(1, $result['values']['next_pay_date']['api.return']);
   }
@@ -92,7 +92,7 @@ public function testGetfieldsPledge() {
   /**
    * Test get pledge api.
    */
-  public function testGetPledge() {
+  public function testGetPledge(): void {
 
     $this->_pledge = $this->callAPISuccess('pledge', 'create', $this->_params);
     $params = [
@@ -119,7 +119,7 @@ public function testGetPledge() {
   /**
    * Test 'return.pledge_financial_type' => 1 works.
    */
-  public function testGetPledgeWithReturn() {
+  public function testGetPledgeWithReturn(): void {
 
     $this->_pledge = $this->callAPISuccess('pledge', 'create', $this->_params);
     $params = [
@@ -137,7 +137,7 @@ public function testGetPledgeWithReturn() {
    *
    * This is for legacy compatibility
    */
-  public function testGetPledgeWithReturnLegacy() {
+  public function testGetPledgeWithReturnLegacy(): void {
 
     $this->_pledge = $this->callAPISuccess('pledge', 'create', $this->_params);
     $params = [
@@ -153,7 +153,7 @@ public function testGetPledgeWithReturnLegacy() {
   /**
    * Test date legacy date filters like pledge_start_date_high.
    */
-  public function testPledgeGetReturnFilters() {
+  public function testPledgeGetReturnFilters(): void {
     $this->callAPISuccess('pledge', 'create', $this->_params);
 
     $overdueParams = [
@@ -175,7 +175,7 @@ public function testPledgeGetReturnFilters() {
   /**
    * Create 2 pledges - see if we can get by status id.
    */
-  public function testGetOverduePledge() {
+  public function testGetOverduePledge(): void {
     $overdueParams = [
       'scheduled_date' => 'first saturday of march last year',
       'start_date' => 'first saturday of march last year',
@@ -195,7 +195,7 @@ public function testGetOverduePledge() {
   /**
    * Test pledge_status option group
    */
-  public function testOptionGroupForPledgeStatus() {
+  public function testOptionGroupForPledgeStatus(): void {
     $pledgeOg = $this->callAPISuccess('OptionGroup', 'get', [
       'name' => "pledge_status",
     ]);
@@ -214,7 +214,7 @@ public function testOptionGroupForPledgeStatus() {
   /**
    * Create 2 pledges - see if we can get by status id.
    */
-  public function testSortParamPledge() {
+  public function testSortParamPledge(): void {
     $pledge1 = $this->callAPISuccess('pledge', 'create', $this->_params);
     $overdueParams = [
       'scheduled_date' => 'first saturday of march last year',
@@ -244,7 +244,7 @@ public function testSortParamPledge() {
     $this->callAPISuccess('pledge', 'delete', ['id' => $pledge2['id']]);
   }
 
-  public function testCreatePledge() {
+  public function testCreatePledge(): void {
 
     $result = $this->callAPISuccess('pledge', 'create', $this->_params);
     $this->assertEquals($result['values'][0]['amount'], 100.00);
@@ -270,7 +270,7 @@ public function testCreatePledge() {
   /**
    * Test that pledge with weekly schedule calculates dates correctly.
    */
-  public function testCreatePledgeWeeklySchedule() {
+  public function testCreatePledgeWeeklySchedule(): void {
     $params = [
       'scheduled_date' => '20110510',
       'frequency_unit' => 'week',
@@ -293,7 +293,7 @@ public function testCreatePledgeWeeklySchedule() {
   /**
    * Test that pledge with weekly schedule calculates dates correctly.
    */
-  public function testCreatePledgeMontlySchedule() {
+  public function testCreatePledgeMontlySchedule(): void {
     $params = [
       'scheduled_date' => '20110510',
       'frequency_unit' => 'Month',
@@ -310,7 +310,7 @@ public function testCreatePledgeMontlySchedule() {
    * Pledge status id left empty as it is not a required field
    * http://issues.civicrm.org/jira/browse/CRM-8551
    */
-  public function testCreatePledgeSinglePayment() {
+  public function testCreatePledgeSinglePayment(): void {
     $params = [
       'scheduled_date' => '20110510',
       'frequency_unit' => 'week',
@@ -338,7 +338,7 @@ public function testCreatePledgeSinglePayment() {
    *
    * Pledge field behaviour is a bit random & so pledge has come to try to handle both unique & non -unique fields.
    */
-  public function testCreatePledgeWithNonUnique() {
+  public function testCreatePledgeWithNonUnique(): void {
     $params = $this->_params;
     $params['original_installment_amount'] = $params['pledge_original_installment_amount'];
 
@@ -358,7 +358,7 @@ public function testCreatePledgeWithNonUnique() {
   /**
    * Test cancelling a pledge.
    */
-  public function testCreateCancelPledge() {
+  public function testCreateCancelPledge(): void {
 
     $result = $this->callAPISuccess('pledge', 'create', $this->_params);
     $this->assertEquals(2, $result['values'][0]['status_id']);
@@ -376,7 +376,7 @@ public function testCreateCancelPledge() {
   /**
    * Test that status is set to pending.
    */
-  public function testCreatePledgeNoStatus() {
+  public function testCreatePledgeNoStatus(): void {
 
     $params = $this->_params;
     unset($params['status_id']);
@@ -391,7 +391,7 @@ public function testCreatePledgeNoStatus() {
   /**
    * Update Pledge.
    */
-  public function testCreateUpdatePledge() {
+  public function testCreateUpdatePledge(): void {
     // we test 'sequential' param here too
     $pledgeID = $this->pledgeCreate(['contact_id' => $this->_individualId]);
     $old_params = [
@@ -439,7 +439,7 @@ public function testCreateUpdatePledge() {
    *
    * We test 'sequential' param here too.
    */
-  public function testCreateUpdatePledgeLegacy() {
+  public function testCreateUpdatePledgeLegacy(): void {
     $pledgeID = $this->pledgeCreate(['contact_id' => $this->_individualId]);
     $old_params = [
       'id' => $pledgeID,
@@ -482,14 +482,14 @@ public function testCreateUpdatePledgeLegacy() {
   /**
    * Failure test for delete without id.
    */
-  public function testDeleteEmptyParamsPledge() {
+  public function testDeleteEmptyParamsPledge(): void {
     $this->callAPIFailure('pledge', 'delete', [], 'Mandatory key(s) missing from params array: id');
   }
 
   /**
    * Failure test for invalid pledge id.
    */
-  public function testDeleteWrongParamPledge() {
+  public function testDeleteWrongParamPledge(): void {
     $params = [
       'pledge_source' => 'SSF',
     ];
@@ -499,7 +499,7 @@ public function testDeleteWrongParamPledge() {
   /**
    * Legacy support for pledge_id.
    */
-  public function testDeletePledge() {
+  public function testDeletePledge(): void {
 
     $pledgeID = $this->pledgeCreate(['contact_id' => $this->_individualId]);
     $params = [
@@ -511,7 +511,7 @@ public function testDeletePledge() {
   /**
    * Standard is to accept id.
    */
-  public function testDeletePledgeUseID() {
+  public function testDeletePledgeUseID(): void {
 
     $pledgeID = $this->pledgeCreate(['contact_id' => $this->_individualId]);
     $params = [
@@ -526,7 +526,7 @@ public function testDeletePledgeUseID() {
    * Note that the function gives incorrect results if no pledges exist as it does a
    * contact search instead - test only checks that the get finds the one existing
    */
-  public function testGetEmpty() {
+  public function testGetEmpty(): void {
     $this->callAPISuccess('pledge', 'create', $this->_params);
     $result = $this->callAPISuccess('pledge', 'get', []);
     $this->assertAPISuccess($result, "This test is failing because it's acting like a contact get when no params set. Not sure the fix");
diff --git a/tests/phpunit/api/v3/PriceFieldValueTest.php b/tests/phpunit/api/v3/PriceFieldValueTest.php
index 38ee65e7ef0b..378151f05f18 100644
--- a/tests/phpunit/api/v3/PriceFieldValueTest.php
+++ b/tests/phpunit/api/v3/PriceFieldValueTest.php
@@ -119,7 +119,7 @@ public function tearDown(): void {
     parent::tearDown();
   }
 
-  public function testCreatePriceFieldValue() {
+  public function testCreatePriceFieldValue(): void {
     $result = $this->callAPISuccess('PriceFieldValue', 'create', $this->params);
     $this->assertAPISuccess($result);
     $this->assertEquals(1, $result['count']);
@@ -138,7 +138,7 @@ public function testGetBasicPriceFieldValue(): void {
     $this->callAPISuccess('price_field_value', 'delete', ['id' => $createResult['id']]);
   }
 
-  public function testDeletePriceFieldValue() {
+  public function testDeletePriceFieldValue(): void {
     $startCount = $this->callAPISuccess('PriceFieldValue', 'getcount', []);
     $createResult = $this->callAPISuccess('PriceFieldValue', 'create', $this->params);
     $deleteParams = ['id' => $createResult['id']];
@@ -153,7 +153,7 @@ public function testGetFieldsPriceFieldValue(): void {
     $this->assertEquals(1, $result['values']['max_value']['type']);
   }
 
-  public function testCreatePriceFieldValuewithMultipleTerms() {
+  public function testCreatePriceFieldValuewithMultipleTerms(): void {
     $params = [
       'price_field_id' => $this->priceFieldID2,
       'membership_type_id' => $this->membershipTypeID,
@@ -170,7 +170,7 @@ public function testCreatePriceFieldValuewithMultipleTerms() {
     $this->callAPISuccess('PriceFieldValue', 'delete', ['id' => $result['id']]);
   }
 
-  public function testGetPriceFieldValuewithMultipleTerms() {
+  public function testGetPriceFieldValuewithMultipleTerms(): void {
     $params2 = [
       'price_field_id' => $this->priceFieldID2,
       'membership_type_id' => $this->membershipTypeID,
diff --git a/tests/phpunit/api/v3/PriceSetTest.php b/tests/phpunit/api/v3/PriceSetTest.php
index de91f6249d06..17110ae0b881 100644
--- a/tests/phpunit/api/v3/PriceSetTest.php
+++ b/tests/phpunit/api/v3/PriceSetTest.php
@@ -41,7 +41,7 @@ public function setUp(): void {
   /**
    * Test create price set.
    */
-  public function testCreatePriceSet() {
+  public function testCreatePriceSet(): void {
     $result = $this->callAPISuccess($this->_entity, 'create', $this->_params);
     $this->assertEquals(1, $result['count']);
     $this->assertNotNull($result['values'][$result['id']]['id']);
@@ -51,7 +51,7 @@ public function testCreatePriceSet() {
   /**
    * Test for creating price sets used for both events and contributions.
    */
-  public function testCreatePriceSetForEventAndContribution() {
+  public function testCreatePriceSetForEventAndContribution(): void {
     // Create the price set
     $createParams = [
       'name' => 'some_price_set',
@@ -74,7 +74,7 @@ public function testCreatePriceSetForEventAndContribution() {
   /**
    * Check that no name doesn't cause failure.
    */
-  public function testCreatePriceSetNoName() {
+  public function testCreatePriceSetNoName(): void {
     $params = $this->_params;
     unset($params['name']);
     $this->callAPISuccess($this->_entity, 'create', $params);
@@ -82,7 +82,7 @@ public function testCreatePriceSetNoName() {
 
   /**
    */
-  public function testGetBasicPriceSet() {
+  public function testGetBasicPriceSet(): void {
     $getParams = [
       'name' => 'default_contribution_amount',
     ];
@@ -90,7 +90,7 @@ public function testGetBasicPriceSet() {
     $this->assertEquals(1, $getResult['count']);
   }
 
-  public function testEventPriceSet() {
+  public function testEventPriceSet(): void {
     $event = $this->callAPISuccess('event', 'create', [
       'title' => 'Event with Price Set',
       'event_type_id' => 1,
@@ -113,7 +113,7 @@ public function testEventPriceSet() {
     $this->assertEquals(['civicrm_event' => [$event['id']]], $result['values'][$createResult['id']]['entity']);
   }
 
-  public function testDeletePriceSet() {
+  public function testDeletePriceSet(): void {
     $startCount = $this->callAPISuccess($this->_entity, 'getcount', []);
     $createResult = $this->callAPISuccess($this->_entity, 'create', $this->_params);
     $deleteParams = ['id' => $createResult['id']];
@@ -122,7 +122,7 @@ public function testDeletePriceSet() {
     $this->assertEquals($startCount, $endCount);
   }
 
-  public function testGetFieldsPriceSet() {
+  public function testGetFieldsPriceSet(): void {
     $result = $this->callAPISuccess($this->_entity, 'getfields', ['action' => 'create']);
     $this->assertEquals(16, $result['values']['is_quick_config']['type']);
   }
diff --git a/tests/phpunit/api/v3/ProductTest.php b/tests/phpunit/api/v3/ProductTest.php
index d68c3e9d2a75..4e7882c72a4f 100644
--- a/tests/phpunit/api/v3/ProductTest.php
+++ b/tests/phpunit/api/v3/ProductTest.php
@@ -27,12 +27,12 @@ public function setUp(): void {
     ];
   }
 
-  public function testGetFields() {
+  public function testGetFields(): void {
     $fields = $this->callAPISuccess($this->_entity, 'getfields', ['action' => 'create']);
     $this->assertArrayHasKey('period_type', $fields['values']);
   }
 
-  public function testGetOptions() {
+  public function testGetOptions(): void {
     $options = $this->callAPISuccess($this->_entity, 'getoptions', ['field' => 'period_type']);
     $this->assertArrayHasKey('rolling', $options['values']);
   }
diff --git a/tests/phpunit/api/v3/RelationshipTest.php b/tests/phpunit/api/v3/RelationshipTest.php
index 7a3f3fcb5a96..37df183594d0 100644
--- a/tests/phpunit/api/v3/RelationshipTest.php
+++ b/tests/phpunit/api/v3/RelationshipTest.php
@@ -668,7 +668,7 @@ public function testRelationshipCreateDuplicateWithCustomFields2(): void {
    * does not.
    * FIXME: Api4
    */
-  public function testRelationshipCreateDuplicateWithCustomFields3() {
+  public function testRelationshipCreateDuplicateWithCustomFields3(): void {
     $this->createCustomGroupWithFieldsOfAllTypes();
 
     $custom_params_1 = [
@@ -698,7 +698,7 @@ public function testRelationshipCreateDuplicateWithCustomFields3() {
   /**
    * Check with valid params array.
    */
-  public function testRelationshipsGet() {
+  public function testRelationshipsGet(): void {
     $relParams = [
       'contact_id_a' => $this->_cId_a,
       'contact_id_b' => $this->_cId_b,
@@ -941,7 +941,7 @@ public function testGetTypeOperators($version) {
   /**
    * Check with invalid relationshipType Id.
    */
-  public function testRelationshipTypeAddInvalidId() {
+  public function testRelationshipTypeAddInvalidId(): void {
     $relTypeParams = [
       'id' => 'invalid',
       'name_a_b' => 'Relation 1 for delete',
@@ -956,7 +956,7 @@ public function testRelationshipTypeAddInvalidId() {
   /**
    * Check with valid data with contact_b.
    */
-  public function testGetRelationshipWithContactB() {
+  public function testGetRelationshipWithContactB(): void {
     $relParams = [
       'contact_id_a' => $this->_cId_a,
       'contact_id_b' => $this->_cId_b,
@@ -1097,7 +1097,7 @@ public function testGetRelationshipByTypeArrayDAO(int $version): void {
    * We should get 1 result without or with correct relationship type id & 0 with
    * an incorrect one
    */
-  public function testGetRelationshipByTypeArrayReciprocal() {
+  public function testGetRelationshipByTypeArrayReciprocal(): void {
     $this->callAPISuccess($this->entity, 'create', $this->_params);
     $org3 = $this->organizationCreate();
     // lets just assume built in ones aren't being messed with!
@@ -1382,7 +1382,7 @@ public function testRelationshipCreateWithEmployerData(): void {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testDisableExpiredRelationships() {
+  public function testDisableExpiredRelationships(): void {
     // Step 1: Create a current employer relationship with Org A
     $params = [
       'relationship_type_id' => '5',
@@ -1451,7 +1451,7 @@ public function testDisableExpiredRelationships() {
    * of something. It's now mostly testing a different variation of
    * relationship + the default in api3 being to not check permissions.
    */
-  public function testCreateWithLesserPermissions() {
+  public function testCreateWithLesserPermissions(): void {
     CRM_Core_Config::singleton()->userPermissionClass->permissions = [];
     $params = [
       'contact_id_a' => $this->_cId_a,
diff --git a/tests/phpunit/api/v3/RelationshipTypeTest.php b/tests/phpunit/api/v3/RelationshipTypeTest.php
index de64804849e8..0aa621c2aaf1 100644
--- a/tests/phpunit/api/v3/RelationshipTypeTest.php
+++ b/tests/phpunit/api/v3/RelationshipTypeTest.php
@@ -101,7 +101,7 @@ public function testRelationshipTypeDeleteWithoutRequired($version) {
   /**
    * Check with incorrect required fields.
    */
-  public function testRelationshipTypeDeleteWithIncorrectData() {
+  public function testRelationshipTypeDeleteWithIncorrectData(): void {
     $params = [
       'id' => 'abcd',
       'name_b_a' => 'Relation 2 delete with incorrect',
diff --git a/tests/phpunit/api/v3/ReportTemplateTest.php b/tests/phpunit/api/v3/ReportTemplateTest.php
index fcccfc7038d7..771b7c6faf72 100644
--- a/tests/phpunit/api/v3/ReportTemplateTest.php
+++ b/tests/phpunit/api/v3/ReportTemplateTest.php
@@ -571,7 +571,7 @@ public function testContributionSummaryWithNotINSmartGroupFilter(string $templat
    *
    * @throws \CRM_Core_Exception
    */
-  public function testCaseDetailsCaseTypeHeader() {
+  public function testCaseDetailsCaseTypeHeader(): void {
     $this->callAPISuccess('report_template', 'getrows', [
       'report_id' => 'case/detail',
       'fields' => ['subject' => 1, 'client_sort_name' => 1],
@@ -590,7 +590,7 @@ public function testCaseDetailsCaseTypeHeader() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testContributionDetailSoftCredits() {
+  public function testContributionDetailSoftCredits(): void {
     $contactID = $this->individualCreate();
     $contactID2 = $this->individualCreate();
     $this->contributionCreate(['contact_id' => $contactID, 'api.ContributionSoft.create' => ['amount' => 5, 'contact_id' => $contactID2]]);
@@ -612,7 +612,7 @@ public function testContributionDetailSoftCredits() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testContributionDetailSoftCreditsOnly() {
+  public function testContributionDetailSoftCreditsOnly(): void {
     $contactID = $this->individualCreate();
     $contactID2 = $this->individualCreate();
     $this->contributionCreate(['contact_id' => $contactID, 'api.ContributionSoft.create' => ['amount' => 5, 'contact_id' => $contactID2]]);
@@ -704,7 +704,7 @@ protected function assertNumberOfContactsInResult(int $numberExpected, array $ro
    *
    * @throws \CRM_Core_Exception
    */
-  public function testContributionSummaryWithTwoGroups() {
+  public function testContributionSummaryWithTwoGroups(): void {
     $groupID = $this->setUpPopulatedGroup();
     $groupID2 = $this->setUpPopulatedSmartGroup();
     $rows = $this->callAPISuccess('report_template', 'getrows', [
@@ -721,7 +721,7 @@ public function testContributionSummaryWithTwoGroups() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testContributionSummaryGroupByContributionStatus() {
+  public function testContributionSummaryGroupByContributionStatus(): void {
     $params = [
       'report_id' => 'contribute/summary',
       'fields' => ['total_amount' => 1, 'country_id' => 1],
@@ -739,7 +739,7 @@ public function testContributionSummaryGroupByContributionStatus() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testContributionSummaryGroupByYearFrequency() {
+  public function testContributionSummaryGroupByYearFrequency(): void {
     $params = [
       'report_id' => 'contribute/summary',
       'fields' => ['total_amount' => 1, 'country_id' => 1],
diff --git a/tests/phpunit/api/v3/SelectQueryTest.php b/tests/phpunit/api/v3/SelectQueryTest.php
index 183772d2f800..da9a39273a29 100644
--- a/tests/phpunit/api/v3/SelectQueryTest.php
+++ b/tests/phpunit/api/v3/SelectQueryTest.php
@@ -26,7 +26,7 @@ public function setUp(): void {
     CRM_Utils_Hook::singleton()->setHook('civicrm_selectWhereClause', [$this, 'hook_civicrm_selectWhereClause']);
   }
 
-  public function testHookPhoneClause() {
+  public function testHookPhoneClause(): void {
     $person1 = $this->callAPISuccess('Contact', 'create', ['contact_type' => 'Individual', 'first_name' => 'Bob', 'last_name' => 'Tester']);
     $cid = $person1['id'];
     for ($number = 1; $number < 6; ++$number) {
@@ -43,7 +43,7 @@ public function testHookPhoneClause() {
     $this->assertEquals(3, $phone['phone']);
   }
 
-  public function testHookContactClause() {
+  public function testHookContactClause(): void {
     $person1 = $this->callAPISuccess('Contact', 'create', ['contact_type' => 'Individual', 'first_name' => 'Bob', 'last_name' => 'Tester', 'email' => 'bob@test.er']);
     $person2 = $this->callAPISuccess('Contact', 'create', ['contact_type' => 'Individual', 'first_name' => 'Tom', 'last_name' => 'Tester', 'email' => 'tom@test.er']);
     $person3 = $this->callAPISuccess('Contact', 'create', ['contact_type' => 'Individual', 'first_name' => 'Tim', 'last_name' => 'Tester', 'email' => 'tim@test.er']);
diff --git a/tests/phpunit/api/v3/StateProvinceTest.php b/tests/phpunit/api/v3/StateProvinceTest.php
index 9fdfbf0b9f7c..a3ee1c643189 100644
--- a/tests/phpunit/api/v3/StateProvinceTest.php
+++ b/tests/phpunit/api/v3/StateProvinceTest.php
@@ -32,7 +32,7 @@ public function setUp(): void {
   /**
    * @dataProvider versionThreeAndFour
    */
-  public function testCreateStateProvince() {
+  public function testCreateStateProvince(): void {
     $result = $this->callAPISuccess('StateProvince', 'create', $this->_params);
     $this->assertEquals(1, $result['count']);
     $this->assertNotNull($result['values'][$result['id']]['id']);
@@ -42,7 +42,7 @@ public function testCreateStateProvince() {
   /**
    * @dataProvider versionThreeAndFour
    */
-  public function testDeleteStateProvince() {
+  public function testDeleteStateProvince(): void {
     // Create
     $create = $this->callAPISuccess('StateProvince', 'create', $this->_params);
 
@@ -59,7 +59,7 @@ public function testDeleteStateProvince() {
    * Test with empty params
    * @dataProvider versionThreeAndFour
    */
-  public function testGetEmptyParams() {
+  public function testGetEmptyParams(): void {
     $result = $this->callAPISuccess('StateProvince', 'Get', []);
   }
 
@@ -67,7 +67,7 @@ public function testGetEmptyParams() {
    * Test with wrong params
    * @dataProvider versionThreeAndFour
    */
-  public function testGetWrongParams() {
+  public function testGetWrongParams(): void {
     $this->callAPIFailure('StateProvince', 'Get', ['id' => 'abc']);
   }
 
@@ -75,7 +75,7 @@ public function testGetWrongParams() {
    * Test get
    * @dataProvider versionThreeAndFour
    */
-  public function testGet() {
+  public function testGet(): void {
     $province = $this->callAPISuccess('StateProvince', 'create', $this->_params);
     $params = [
       'name' => $this->_params['name'],
@@ -89,7 +89,7 @@ public function testGet() {
    * There cannot be two state/provinces with the same name in the same country.
    * @dataProvider versionThreeAndFour
    */
-  public function testCreateDuplicateFail() {
+  public function testCreateDuplicateFail(): void {
     $params = $this->_params;
     unset($params['id']);
     $this->callAPISuccess('StateProvince', 'create', $params);
diff --git a/tests/phpunit/api/v3/SurveyRespondantTest.php b/tests/phpunit/api/v3/SurveyRespondantTest.php
index 7ae47cfa5f7a..7c4edbc604a6 100644
--- a/tests/phpunit/api/v3/SurveyRespondantTest.php
+++ b/tests/phpunit/api/v3/SurveyRespondantTest.php
@@ -38,7 +38,7 @@ public function setUp(): void {
   /**
    * Test survey respondent get.
    */
-  public function testGetSurveyRespondants() {
+  public function testGetSurveyRespondants(): void {
     $result = $this->callAPISuccess("SurveyRespondant", "get", $this->params);
   }
 
diff --git a/tests/phpunit/api/v3/SyntaxConformanceTest.php b/tests/phpunit/api/v3/SyntaxConformanceTest.php
index 72b6f876ff8c..ab128ba111c5 100644
--- a/tests/phpunit/api/v3/SyntaxConformanceTest.php
+++ b/tests/phpunit/api/v3/SyntaxConformanceTest.php
@@ -1632,7 +1632,7 @@ private function getMockableBAOObjects($entityName, $count = 2): array {
    * In this example, the event 'title' is subject to encoding, but the
    * event 'description' is not.
    */
-  public function testEncodeDecodeConsistency() {
+  public function testEncodeDecodeConsistency(): void {
     // Create example
     $createResult = civicrm_api('Event', 'Create', [
       'version' => 3,
diff --git a/tests/phpunit/api/v3/TagTest.php b/tests/phpunit/api/v3/TagTest.php
index 9e7e2030dfad..d975f59889fb 100644
--- a/tests/phpunit/api/v3/TagTest.php
+++ b/tests/phpunit/api/v3/TagTest.php
@@ -119,7 +119,7 @@ public function testCreatePasstagInParams($version) {
    * Test civicrm_tag_create - success expected.
    * Skipping v4 because used_for is an array
    */
-  public function testCreate() {
+  public function testCreate(): void {
     $params = [
       'name' => 'Super Heros',
       'description' => 'Outside undie-wearers',
@@ -137,7 +137,7 @@ public function testCreate() {
    *
    * Skipping v4 because used_for is an array
    */
-  public function testCreateEntitySpecificTag() {
+  public function testCreateEntitySpecificTag(): void {
     $params = [
       'name' => 'New Tag4',
       'description' => 'This is description for New Activity tag',
@@ -193,13 +193,13 @@ public function testTagDeleteCorrectSyntax($version) {
     unset($this->ids['tag']);
   }
 
-  public function testTagGetfields() {
+  public function testTagGetfields(): void {
     $params = ['action' => 'create'];
     $result = $this->callAPISuccess('tag', 'getfields', $params);
     $this->assertEquals('civicrm_contact', $result['values']['used_for']['api.default']);
   }
 
-  public function testTagGetList() {
+  public function testTagGetList(): void {
     $params = [
       'input' => $this->tag['name'],
       'extra' => ['used_for'],
diff --git a/tests/phpunit/api/v3/UserTest.php b/tests/phpunit/api/v3/UserTest.php
index 0061d133e549..3f52efc78d7b 100644
--- a/tests/phpunit/api/v3/UserTest.php
+++ b/tests/phpunit/api/v3/UserTest.php
@@ -31,7 +31,7 @@ public function setUp(): void {
     ];
   }
 
-  public function testUserGet() {
+  public function testUserGet(): void {
     $result = $this->callAPISuccess($this->_entity, 'get', $this->params);
     $this->assertEquals(1, $result['count']);
     $this->assertEquals($this->contactID, $result['values'][0]['contact_id']);
@@ -42,7 +42,7 @@ public function testUserGet() {
   /**
    * Test retrieval of label metadata.
    */
-  public function testGetFields() {
+  public function testGetFields(): void {
     $result = $this->callAPISuccess($this->_entity, 'getfields', ['action' => 'get']);
     $this->assertArrayKeyExists('name', $result['values']);
   }
diff --git a/tests/phpunit/api/v3/UtilsTest.php b/tests/phpunit/api/v3/UtilsTest.php
index 06d5dcdb72fc..de7c001e134d 100644
--- a/tests/phpunit/api/v3/UtilsTest.php
+++ b/tests/phpunit/api/v3/UtilsTest.php
@@ -30,7 +30,7 @@ protected function setUp(): void {
     $this->useTransaction(TRUE);
   }
 
-  public function testCheckPermissionReturn() {
+  public function testCheckPermissionReturn(): void {
     $check = ['check_permissions' => TRUE];
     $config = CRM_Core_Config::singleton();
     $config->userPermissionClass->permissions = [];
@@ -47,7 +47,7 @@ public function testCheckPermissionReturn() {
     $this->assertTrue($this->runPermissionCheck('contact', 'create', $check), 'overfluous permissions should be enough');
   }
 
-  public function testCheckPermissionThrow() {
+  public function testCheckPermissionThrow(): void {
     $check = ['check_permissions' => TRUE];
     $config = CRM_Core_Config::singleton();
     try {
@@ -63,7 +63,7 @@ public function testCheckPermissionThrow() {
     $this->assertTrue($this->runPermissionCheck('contact', 'create', $check), 'overfluous permissions should return true');
   }
 
-  public function testCheckPermissionSkip() {
+  public function testCheckPermissionSkip(): void {
     $config = CRM_Core_Config::singleton();
     $config->userPermissionClass->permissions = ['access CiviCRM'];
     $params = ['check_permissions' => TRUE];
@@ -153,7 +153,7 @@ public function runPermissionCheck($entity, $action, $params, $throws = FALSE) {
   /**
    * Test verify mandatory - includes DAO & passed as well as empty & NULL fields
    */
-  public function testVerifyMandatory() {
+  public function testVerifyMandatory(): void {
     _civicrm_api3_initialize(TRUE);
     $params = [
       'entity_table' => 'civicrm_contact',
@@ -177,7 +177,7 @@ public function testVerifyMandatory() {
   /**
    * Test verify one mandatory - includes DAO & passed as well as empty & NULL fields
    */
-  public function testVerifyOneMandatory() {
+  public function testVerifyOneMandatory(): void {
     _civicrm_api3_initialize(TRUE);
     $params = [
       'entity_table' => 'civicrm_contact',
@@ -202,7 +202,7 @@ public function testVerifyOneMandatory() {
   /**
    * Test verify one mandatory - includes DAO & passed as well as empty & NULL fields
    */
-  public function testVerifyOneMandatoryOneSet() {
+  public function testVerifyOneMandatoryOneSet(): void {
     _civicrm_api3_initialize(TRUE);
     $params = [
       'version' => 3,
@@ -224,7 +224,7 @@ public function testVerifyOneMandatoryOneSet() {
   /**
    * Test GET DAO function returns DAO.
    */
-  public function testGetDAO() {
+  public function testGetDAO(): void {
     $params = [
       'civicrm_api3_custom_group_get' => 'CRM_Core_DAO_CustomGroup',
       'custom_group' => 'CRM_Core_DAO_CustomGroup',
@@ -244,7 +244,7 @@ public function testGetDAO() {
   /**
    * Test GET BAO function returns BAO when it exists.
    */
-  public function testGetBAO() {
+  public function testGetBAO(): void {
     $params = [
       'civicrm_api3_website_get' => 'CRM_Core_BAO_Website',
       'civicrm_api3_survey_get' => 'CRM_Campaign_BAO_Survey',
@@ -267,7 +267,7 @@ public function testGetBAO() {
    * @throws \CRM_Core_Exception
    * @throws \Exception
    */
-  public function test_civicrm_api3_validate_fields() {
+  public function test_civicrm_api3_validate_fields(): void {
     $params = ['relationship_start_date' => '2010-12-20', 'relationship_end_date' => ''];
     $fields = civicrm_api3('relationship', 'getfields', ['action' => 'get']);
     _civicrm_api3_validate_fields('relationship', 'get', $params, $fields['values']);
@@ -275,7 +275,7 @@ public function test_civicrm_api3_validate_fields() {
     $this->assertEquals('', $params['relationship_end_date']);
   }
 
-  public function test_civicrm_api3_validate_fields_membership() {
+  public function test_civicrm_api3_validate_fields_membership(): void {
     $params = [
       'start_date' => '2010-12-20',
       'end_date' => '',
@@ -291,7 +291,7 @@ public function test_civicrm_api3_validate_fields_membership() {
     $this->assertEquals('20101220000000', $params['membership_join_date'], 'join_date not set in line ' . __LINE__);
   }
 
-  public function test_civicrm_api3_validate_fields_event() {
+  public function test_civicrm_api3_validate_fields_event(): void {
 
     $params = [
       'registration_start_date' => 20080601,
@@ -307,7 +307,7 @@ public function test_civicrm_api3_validate_fields_event() {
     $this->assertEquals('20080601000000', $params['registration_start_date']);
   }
 
-  public function test_civicrm_api3_validate_fields_exception() {
+  public function test_civicrm_api3_validate_fields_exception(): void {
     $params = [
       'membership_join_date' => 'abc',
     ];
@@ -320,7 +320,7 @@ public function test_civicrm_api3_validate_fields_exception() {
     }
   }
 
-  public function testGetFields() {
+  public function testGetFields(): void {
     $result = $this->callAPISuccess('membership', 'getfields', []);
     $this->assertArrayHasKey('values', $result);
     $result = $this->callAPISuccess('relationship', 'getfields', []);
@@ -451,7 +451,7 @@ public function testBasicArrayGet($records, $params, $resultIds) {
     $this->assertEquals($slice, array_values(CRM_Utils_Array::collect('id', $r3['values'])));
   }
 
-  public function testBasicArrayGetReturn() {
+  public function testBasicArrayGetReturn(): void {
     $records = [
       ['snack_id' => 'a', 'fruit' => 'apple', 'cheese' => 'swiss'],
       ['snack_id' => 'b', 'fruit' => 'grape', 'cheese' => 'cheddar'],
@@ -498,7 +498,7 @@ public function testBasicArrayGetReturn() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testTimeStampChecking() {
+  public function testTimeStampChecking(): void {
     CRM_Core_DAO::executeQuery("INSERT INTO civicrm_mailing (id, modified_date) VALUES (25, '2016-06-30 12:52:52')");
     $this->assertTrue(_civicrm_api3_compare_timestamps('2017-02-15 16:00:00', 25, 'Mailing'));
     $this->callAPISuccess('Mailing', 'create', ['id' => 25, 'subject' => 'Test Subject']);
@@ -511,7 +511,7 @@ public function testTimeStampChecking() {
    *
    * @throws \CRM_Core_Exception
    */
-  public function testKeyConstraintCheck() {
+  public function testKeyConstraintCheck(): void {
     $fieldInfo = $this->callAPISuccess('Contribution', 'getfields', [])['values']['financial_type_id'];
     _civicrm_api3_validate_constraint(1, 'financial_type_id', $fieldInfo, 'Contribution');
     _civicrm_api3_validate_constraint('Donation', 'financial_type_id', $fieldInfo, 'Contribution');
diff --git a/tests/phpunit/api/v3/ValidateTest.php b/tests/phpunit/api/v3/ValidateTest.php
index 473f397ccac7..560ac81be17b 100644
--- a/tests/phpunit/api/v3/ValidateTest.php
+++ b/tests/phpunit/api/v3/ValidateTest.php
@@ -24,7 +24,7 @@ protected function setUp(): void {
     parent::setUp();
   }
 
-  public function testEmptyContactValidate() {
+  public function testEmptyContactValidate(): void {
     $validation = $this->callAPISuccess('Contact', 'validate', ['action' => "create"]);
     $expectedOut = [
       'contact_type' => [
@@ -35,7 +35,7 @@ public function testEmptyContactValidate() {
     $this->assertEquals($validation['values'][0], $expectedOut);
   }
 
-  public function testContributionValidate() {
+  public function testContributionValidate(): void {
     $validation = $this->callAPISuccess('Contribution', 'validate', ['action' => "create", 'total_amount' => "100w"]);
     $totalAmountErrors = [
       'message' => "total_amount is  not a valid amount: 100w",
@@ -51,7 +51,7 @@ public function testContributionValidate() {
     $this->assertEquals($validation['values'][0]['contact_id'], $contactIdErrors);
   }
 
-  public function testContributionDateValidate() {
+  public function testContributionDateValidate(): void {
     $params = [
       'action' => "create",
       'financial_type_id' => "1",
diff --git a/tests/phpunit/api/v3/WebsiteTest.php b/tests/phpunit/api/v3/WebsiteTest.php
index 07e2121461c6..9a089e146547 100644
--- a/tests/phpunit/api/v3/WebsiteTest.php
+++ b/tests/phpunit/api/v3/WebsiteTest.php
@@ -99,7 +99,7 @@ public function testDeleteWebsiteInvalid($version) {
   /**
    * Test retrieval of metadata.
    */
-  public function testGetMetadata() {
+  public function testGetMetadata(): void {
     $result = $this->callAPISuccess($this->_entity, 'get', [
       'options' => [
         'metadata' => ['fields'],
diff --git a/tests/phpunit/api/v4/Action/AutocompleteTest.php b/tests/phpunit/api/v4/Action/AutocompleteTest.php
index d4fef2a47400..2c71219de73d 100644
--- a/tests/phpunit/api/v4/Action/AutocompleteTest.php
+++ b/tests/phpunit/api/v4/Action/AutocompleteTest.php
@@ -143,7 +143,7 @@ public function testContactIconAutocomplete(): void {
     $this->assertEquals('fa-star', $result[2]['icon']);
   }
 
-  public function testAutocompleteValidation() {
+  public function testAutocompleteValidation(): void {
     $lastName = uniqid(__FUNCTION__);
     $sampleData = [
       [
@@ -199,7 +199,7 @@ public function testAutocompleteValidation() {
     $this->assertCount(1, $result);
   }
 
-  public function testAutocompletePager() {
+  public function testAutocompletePager(): void {
     \Civi::settings()->set('search_autocomplete_count', 10);
     MockBasicEntity::delete()->addWhere('identifier', '>', 0)->execute();
     $sampleData = [];
@@ -234,7 +234,7 @@ public function testAutocompletePager() {
     $this->assertEquals(1, $result3->countMatched());
   }
 
-  public function testAutocompleteWithDifferentKey() {
+  public function testAutocompleteWithDifferentKey(): void {
     $label = \CRM_Utils_String::createRandom(10, implode('', range('a', 'z')));
     $sample = $this->saveTestRecords('SavedSearch', [
       'records' => [
diff --git a/tests/phpunit/api/v4/Action/BasicActionsTest.php b/tests/phpunit/api/v4/Action/BasicActionsTest.php
index 2988f3e7a727..0d32c8c8eb78 100644
--- a/tests/phpunit/api/v4/Action/BasicActionsTest.php
+++ b/tests/phpunit/api/v4/Action/BasicActionsTest.php
@@ -55,14 +55,14 @@ private function replaceRecords(&$records) {
     }
   }
 
-  public function testGetInfo() {
+  public function testGetInfo(): void {
     $info = MockBasicEntity::getInfo();
     $this->assertEquals('MockBasicEntity', $info['name']);
     $this->assertEquals(['identifier'], $info['primary_key']);
     $this->assertEquals('identifier', CoreUtil::getIdFieldName('MockBasicEntity'));
   }
 
-  public function testCrud() {
+  public function testCrud(): void {
     MockBasicEntity::delete()->addWhere('identifier', '>', 0)->execute();
 
     $id1 = MockBasicEntity::create()->addValue('foo', 'one')->execute()->first()['identifier'];
@@ -131,7 +131,7 @@ public function testCrud() {
     $this->assertEquals('one updated', $result->first()['foo']);
   }
 
-  public function testReplace() {
+  public function testReplace(): void {
     $objects = [
       ['group' => 'one', 'color' => 'red'],
       ['group' => 'one', 'color' => 'blue'],
@@ -163,7 +163,7 @@ public function testReplace() {
     $this->assertEquals('two', $newObjects[$objects[3]['identifier']]['group']);
   }
 
-  public function testBatchFrobnicate() {
+  public function testBatchFrobnicate(): void {
     $objects = [
       ['group' => 'one', 'color' => 'red', 'number' => 10],
       ['group' => 'one', 'color' => 'blue', 'number' => 20],
@@ -177,7 +177,7 @@ public function testBatchFrobnicate() {
     $this->assertEquals([400, 1600], \CRM_Utils_Array::collect('frobnication', (array) $result));
   }
 
-  public function testGetFields() {
+  public function testGetFields(): void {
     $getFields = MockBasicEntity::getFields()->execute()->indexBy('name');
 
     $this->assertCount(8, $getFields);
@@ -224,7 +224,7 @@ public function testGetFields() {
     $this->assertEquals('yellow', $getFields['fruit']['options'][2]['color']);
   }
 
-  public function testItemsToGet() {
+  public function testItemsToGet(): void {
     $get = MockBasicEntity::get()
       ->addWhere('color', 'NOT IN', ['yellow'])
       ->addWhere('color', 'IN', ['red', 'blue'])
@@ -242,7 +242,7 @@ public function testItemsToGet() {
     $this->assertEmpty(Invasive::call($itemsToGet, ['weight']));
   }
 
-  public function testFieldsToGet() {
+  public function testFieldsToGet(): void {
     $get = MockBasicEntity::get()
       ->addWhere('color', '!=', 'green');
 
@@ -272,7 +272,7 @@ public function testFieldsToGet() {
     $this->assertTrue(Invasive::call($isFieldSelected, ['group']));
   }
 
-  public function testWildcardSelect() {
+  public function testWildcardSelect(): void {
     $records = [
       ['group' => 'one', 'color' => 'red', 'shape' => 'round', 'size' => 'med', 'weight' => 10],
       ['group' => 'two', 'color' => 'blue', 'shape' => 'round', 'size' => 'med', 'weight' => 20],
@@ -291,7 +291,7 @@ public function testWildcardSelect() {
     $this->assertEquals(['shape', 'size', 'weight'], array_keys($result));
   }
 
-  public function testEmptyAndNullOperators() {
+  public function testEmptyAndNullOperators(): void {
     $records = [
       ['id' => NULL],
       ['color' => '', 'weight' => 0],
@@ -336,7 +336,7 @@ public function testEmptyAndNullOperators() {
     $this->assertArrayHasKey($records[2]['identifier'], (array) $result);
   }
 
-  public function testContainsOperators() {
+  public function testContainsOperators(): void {
     $records = [
       ['group' => 'one', 'fruit:name' => ['apple', 'pear'], 'weight' => 11],
       ['group' => 'two', 'fruit:name' => ['pear', 'banana'], 'weight' => 12],
@@ -410,7 +410,7 @@ public function testContainsOperators() {
     $this->assertEquals('one', $result->first()['group']);
   }
 
-  public function testRegexpOperators() {
+  public function testRegexpOperators(): void {
     $records = [
       ['color' => 'red'],
       ['color' => 'blue'],
@@ -432,7 +432,7 @@ public function testRegexpOperators() {
     $this->assertEquals('red', $result[0]['color']);
   }
 
-  public function testPseudoconstantMatch() {
+  public function testPseudoconstantMatch(): void {
     $records = [
       ['group:label' => 'First', 'shape' => 'round', 'fruit:name' => 'banana'],
       ['group:name' => 'two', 'shape' => 'square', 'fruit:label' => 'Pear'],
diff --git a/tests/phpunit/api/v4/Action/ChainTest.php b/tests/phpunit/api/v4/Action/ChainTest.php
index 7e2bb75962b9..2f2a8a6a5adb 100644
--- a/tests/phpunit/api/v4/Action/ChainTest.php
+++ b/tests/phpunit/api/v4/Action/ChainTest.php
@@ -40,7 +40,7 @@ public function tearDown(): void {
     parent::tearDown();
   }
 
-  public function testGetActionsWithFields() {
+  public function testGetActionsWithFields(): void {
     $actions = \Civi\Api4\Activity::getActions()
       ->addChain('fields', \Civi\Api4\Activity::getFields()->setAction('$name'), 'name')
       ->execute()
@@ -49,7 +49,7 @@ public function testGetActionsWithFields() {
     $this->assertEquals('Array', $actions['getActions']['fields']['params']['data_type']);
   }
 
-  public function testGetEntityWithActions() {
+  public function testGetEntityWithActions(): void {
     $entities = \Civi\Api4\Entity::get()
       ->addSelect('name')
       ->setChain([
@@ -63,7 +63,7 @@ public function testGetEntityWithActions() {
     $this->assertArrayNotHasKey('replace', $entities['Entity']['actions']);
   }
 
-  public function testContactCreateWithGroup() {
+  public function testContactCreateWithGroup(): void {
     $firstName = uniqid('cwtf');
     $lastName = uniqid('cwtl');
 
@@ -81,7 +81,7 @@ public function testContactCreateWithGroup() {
     $this->assertEquals($contact['group']['id'], $contact['check_group'][0]['group_id']);
   }
 
-  public function testWithContactRef() {
+  public function testWithContactRef(): void {
     CustomGroup::create()
       ->setCheckPermissions(FALSE)
       ->addValue('title', 'TestActCus')
diff --git a/tests/phpunit/api/v4/Action/ContactApiKeyTest.php b/tests/phpunit/api/v4/Action/ContactApiKeyTest.php
index edfdb6447449..5608ab16ec21 100644
--- a/tests/phpunit/api/v4/Action/ContactApiKeyTest.php
+++ b/tests/phpunit/api/v4/Action/ContactApiKeyTest.php
@@ -29,7 +29,7 @@
  */
 class ContactApiKeyTest extends Api4TestBase implements TransactionalInterface {
 
-  public function testGetApiKey() {
+  public function testGetApiKey(): void {
     \CRM_Core_Config::singleton()->userPermissionClass->permissions = ['access CiviCRM', 'add contacts', 'edit api keys', 'view all contacts', 'edit all contacts'];
     $key = \CRM_Utils_String::createRandom(16, \CRM_Utils_String::ALPHANUMERIC);
     $isSafe = function ($mixed) use ($key) {
@@ -102,7 +102,7 @@ public function testGetApiKey() {
     $this->assertTrue($isSafe($result), "Should NOT reveal secret details ($key): " . var_export($result, 1));
   }
 
-  public function testApiKeyInWhereAndOrderBy() {
+  public function testApiKeyInWhereAndOrderBy(): void {
     \CRM_Core_Config::singleton()->userPermissionClass->permissions = ['access CiviCRM', 'add contacts', 'edit api keys', 'view all contacts', 'edit all contacts'];
     $keyA = 'a' . \CRM_Utils_String::createRandom(15, \CRM_Utils_String::ALPHANUMERIC);
     $keyB = 'b' . \CRM_Utils_String::createRandom(15, \CRM_Utils_String::ALPHANUMERIC);
@@ -180,7 +180,7 @@ public function testApiKeyInWhereAndOrderBy() {
 
   }
 
-  public function testCreateWithInsufficientPermissions() {
+  public function testCreateWithInsufficientPermissions(): void {
     \CRM_Core_Config::singleton()->userPermissionClass->permissions = ['access CiviCRM', 'add contacts'];
     $key = uniqid();
 
@@ -199,7 +199,7 @@ public function testCreateWithInsufficientPermissions() {
     $this->assertStringContainsString('key', $error);
   }
 
-  public function testGetApiKeyViaJoin() {
+  public function testGetApiKeyViaJoin(): void {
     \CRM_Core_Config::singleton()->userPermissionClass->permissions = ['access CiviCRM', 'view all contacts'];
     $key = \CRM_Utils_String::createRandom(16, \CRM_Utils_String::ALPHANUMERIC);
     $isSafe = function ($mixed) use ($key) {
@@ -238,7 +238,7 @@ public function testGetApiKeyViaJoin() {
     $this->assertTrue($isSafe($result), "Should NOT reveal secret details ($key): " . var_export($result, 1));
   }
 
-  public function testUpdateApiKey() {
+  public function testUpdateApiKey(): void {
     \CRM_Core_Config::singleton()->userPermissionClass->permissions = ['access CiviCRM', 'edit all contacts'];
     $key = uniqid();
 
@@ -290,7 +290,7 @@ public function testUpdateApiKey() {
     $this->assertEquals($result['api_key'], "IGotThePower!");
   }
 
-  public function testUpdateOwnApiKey() {
+  public function testUpdateOwnApiKey(): void {
     \CRM_Core_Config::singleton()->userPermissionClass->permissions = ['access CiviCRM', 'edit own api keys', 'edit all contacts'];
     $key = uniqid();
 
@@ -342,7 +342,7 @@ public function testUpdateOwnApiKey() {
     $this->assertEquals($result['api_key'], "MyId!");
   }
 
-  public function testApiKeyWithGetFields() {
+  public function testApiKeyWithGetFields(): void {
     // With sufficient permissions the field should exist
     \CRM_Core_Config::singleton()->userPermissionClass->permissions = ['access CiviCRM', 'edit api keys'];
     $this->assertArrayHasKey('api_key', \civicrm_api4('Contact', 'getFields', [], 'name'));
diff --git a/tests/phpunit/api/v4/Action/ContactChecksumTest.php b/tests/phpunit/api/v4/Action/ContactChecksumTest.php
index 66954ca3226b..9c7b5818a125 100644
--- a/tests/phpunit/api/v4/Action/ContactChecksumTest.php
+++ b/tests/phpunit/api/v4/Action/ContactChecksumTest.php
@@ -28,7 +28,7 @@
  */
 class ContactChecksumTest extends Api4TestBase implements TransactionalInterface {
 
-  public function testGetChecksum() {
+  public function testGetChecksum(): void {
     $contact = Contact::create(FALSE)
       ->addValue('first_name', 'Check')
       ->addValue('last_name', 'Sum')
@@ -45,7 +45,7 @@ public function testGetChecksum() {
     $this->assertTrue($result['valid']);
   }
 
-  public function testValidateChecksum() {
+  public function testValidateChecksum(): void {
     $cid = Contact::create(FALSE)
       ->addValue('first_name', 'Checker')
       ->addValue('last_name', 'Sum')
diff --git a/tests/phpunit/api/v4/Action/ContactDuplicatesTest.php b/tests/phpunit/api/v4/Action/ContactDuplicatesTest.php
index 3e3b1914dea9..cb895c5e5f55 100644
--- a/tests/phpunit/api/v4/Action/ContactDuplicatesTest.php
+++ b/tests/phpunit/api/v4/Action/ContactDuplicatesTest.php
@@ -27,7 +27,7 @@
  */
 class ContactDuplicatesTest extends CustomTestBase {
 
-  public function testGetDuplicatesUnsupervised() {
+  public function testGetDuplicatesUnsupervised(): void {
     $email = uniqid('test@');
 
     $testContacts = $this->saveTestRecords('Contact', [
@@ -44,7 +44,7 @@ public function testGetDuplicatesUnsupervised() {
     $this->assertNotContains($testContacts[3], $found);
   }
 
-  public function testGetFieldsForContactGetDuplicatesAction() {
+  public function testGetFieldsForContactGetDuplicatesAction(): void {
     $fields = Contact::getFields(FALSE)
       ->setAction('getDuplicates')
       ->execute()
@@ -54,7 +54,7 @@ public function testGetFieldsForContactGetDuplicatesAction() {
     $this->assertEquals('Email', $fields['email_primary.email']['entity']);
   }
 
-  public function testGetRuleGroupNames() {
+  public function testGetRuleGroupNames(): void {
     $this->createTestRecord('DedupeRuleGroup', [
       'contact_type' => 'Individual',
       'name' => 'houseRule',
@@ -77,7 +77,7 @@ public function testGetRuleGroupNames() {
     $this->assertContains('houseRule', $meta['params']['dedupeRule']['options']);
   }
 
-  public function testDedupeWithCustomFields() {
+  public function testDedupeWithCustomFields(): void {
     $customGroup = $this->createTestRecord('CustomGroup', ['name' => 'test1']);
 
     $customFieldText = $this->createTestRecord('CustomField', [
diff --git a/tests/phpunit/api/v4/Action/ContactGetTest.php b/tests/phpunit/api/v4/Action/ContactGetTest.php
index cf9255354869..f0ea7858e579 100644
--- a/tests/phpunit/api/v4/Action/ContactGetTest.php
+++ b/tests/phpunit/api/v4/Action/ContactGetTest.php
@@ -29,7 +29,7 @@
  */
 class ContactGetTest extends Api4TestBase implements TransactionalInterface {
 
-  public function testGetDeletedContacts() {
+  public function testGetDeletedContacts(): void {
     $last_name = uniqid('deleteContactTest');
 
     $bob = Contact::create()
@@ -59,7 +59,7 @@ public function testGetDeletedContacts() {
     $this->assertContains($del['id'], $contacts->column('id'));
   }
 
-  public function testGetWithLimit() {
+  public function testGetWithLimit(): void {
     $last_name = uniqid('getWithLimitTest');
 
     $bob = Contact::create()
@@ -137,7 +137,7 @@ public function testEmoji(): void {
     }
   }
 
-  public function testEmptyAndNullOperators() {
+  public function testEmptyAndNullOperators(): void {
     $last_name = uniqid(__FUNCTION__);
 
     $bob = Contact::create()
@@ -199,7 +199,7 @@ public function testEmptyAndNullOperators() {
     $this->assertArrayHasKey($jan['id'], (array) $result);
   }
 
-  public function testRegexpOperators() {
+  public function testRegexpOperators(): void {
     $last_name = uniqid(__FUNCTION__);
 
     $alice = Contact::create()
@@ -230,7 +230,7 @@ public function testRegexpOperators() {
     $this->assertArrayHasKey($jane['id'], (array) $result);
   }
 
-  public function testGetRelatedWithSubType() {
+  public function testGetRelatedWithSubType(): void {
     $org = Contact::create(FALSE)
       ->addValue('contact_type', 'Organization')
       ->addValue('organization_name', 'Run Amok')
@@ -294,7 +294,7 @@ public function testGetRelatedWithSubType() {
     $this->assertEquals(['Student'], $result['Contact_RelationshipCache_Contact_01.contact_sub_type:label']);
   }
 
-  public function testGetWithWhereExpression() {
+  public function testGetWithWhereExpression(): void {
     $last_name = uniqid(__FUNCTION__);
 
     $alice = Contact::create()
@@ -354,7 +354,7 @@ public function testAge(): void {
   /**
    *
    */
-  public function testGetWithCount() {
+  public function testGetWithCount(): void {
     $myName = uniqid('count');
     for ($i = 1; $i <= 20; ++$i) {
       $this->createTestRecord('Contact', [
@@ -375,7 +375,7 @@ public function testGetWithCount() {
 
   }
 
-  public function testGetWithPrimaryEmailPhoneIMAddress() {
+  public function testGetWithPrimaryEmailPhoneIMAddress(): void {
     $lastName = uniqid(__FUNCTION__);
     $email = uniqid() . '@example.com';
     $phone = uniqid('phone');
@@ -408,7 +408,7 @@ public function testGetWithPrimaryEmailPhoneIMAddress() {
     $this->assertNull($results[2]['address_primary.city']);
   }
 
-  public function testBasicContactACLs() {
+  public function testBasicContactACLs(): void {
     $this->createLoggedInUser();
     \CRM_Core_Config::singleton()->userPermissionClass->permissions = [
       'access CiviCRM',
diff --git a/tests/phpunit/api/v4/Action/DateTest.php b/tests/phpunit/api/v4/Action/DateTest.php
index e61a22313e74..50d2e48243d3 100644
--- a/tests/phpunit/api/v4/Action/DateTest.php
+++ b/tests/phpunit/api/v4/Action/DateTest.php
@@ -31,7 +31,7 @@
  */
 class DateTest extends Api4TestBase implements TransactionalInterface {
 
-  public function testRelationshipDate() {
+  public function testRelationshipDate(): void {
     $c1 = Contact::create()
       ->addValue('first_name', 'c')
       ->addValue('last_name', 'one')
@@ -63,7 +63,7 @@ public function testRelationshipDate() {
     $this->assertArrayNotHasKey($r, $result);
   }
 
-  public function testRelativeDateRanges() {
+  public function testRelativeDateRanges(): void {
     $c1 = Contact::create()
       ->addValue('first_name', 'c')
       ->addValue('last_name', 'one')
@@ -146,7 +146,7 @@ public function testRelativeDateRanges() {
     $this->assertNotContains($act[6], $result);
   }
 
-  public function testJoinOnRelativeDate() {
+  public function testJoinOnRelativeDate(): void {
     $c1 = Contact::create(FALSE)
       ->addValue('first_name', 'Contributor')
       ->addValue('last_name', 'One')
diff --git a/tests/phpunit/api/v4/Action/EntitySetUnionTest.php b/tests/phpunit/api/v4/Action/EntitySetUnionTest.php
index 13aff6640664..62c7ec771f3e 100644
--- a/tests/phpunit/api/v4/Action/EntitySetUnionTest.php
+++ b/tests/phpunit/api/v4/Action/EntitySetUnionTest.php
@@ -151,7 +151,7 @@ public function testUnionWithSelectAndOrderBy(): void {
     $this->assertEquals($contacts[0], $result[2]['contact_id_b']);
   }
 
-  public function testUnionWithSelectStar() {
+  public function testUnionWithSelectStar(): void {
     $subType = $this->createTestRecord('ContactType', [
       'parent_id:name' => 'Household',
       'name' => uniqid('HH1'),
diff --git a/tests/phpunit/api/v4/Action/EvaluateConditionTest.php b/tests/phpunit/api/v4/Action/EvaluateConditionTest.php
index 95c6e67962f0..30568cee51a0 100644
--- a/tests/phpunit/api/v4/Action/EvaluateConditionTest.php
+++ b/tests/phpunit/api/v4/Action/EvaluateConditionTest.php
@@ -29,7 +29,7 @@
  */
 class EvaluateConditionTest extends Api4TestBase implements TransactionalInterface {
 
-  public function testEvaluateCondition() {
+  public function testEvaluateCondition(): void {
     $method = [MockBasicEntity::get(), 'evaluateCondition'];
 
     $data = [
diff --git a/tests/phpunit/api/v4/Action/EventTest.php b/tests/phpunit/api/v4/Action/EventTest.php
index 09d14e8a27a8..2841dfa27479 100644
--- a/tests/phpunit/api/v4/Action/EventTest.php
+++ b/tests/phpunit/api/v4/Action/EventTest.php
@@ -32,7 +32,7 @@ class EventTest extends Api4TestBase implements TransactionalInterface {
    *
    * @throws \Civi\API\Exception\UnauthorizedException
    */
-  public function testTemplateFilterByDefault() {
+  public function testTemplateFilterByDefault(): void {
     $t = Event::create()->setValues(['template_title' => 'Big Event', 'is_template' => 1, 'start_date' => 'now', 'event_type_id:name' => 'Meeting'])->execute()->first();
     $e = Event::create()->setValues(['title' => 'Bigger Event', 'start_date' => 'now', 'event_type_id:name' => 'Meeting'])->execute()->first();
     $result = (array) Event::get()->execute()->column('id');
diff --git a/tests/phpunit/api/v4/Action/FkJoinTest.php b/tests/phpunit/api/v4/Action/FkJoinTest.php
index b935da136eed..1170c96599b1 100644
--- a/tests/phpunit/api/v4/Action/FkJoinTest.php
+++ b/tests/phpunit/api/v4/Action/FkJoinTest.php
@@ -51,7 +51,7 @@ public function tearDown(): void {
    * Fetch all phone call activities. Expects a single activity
    * loaded from the data set.
    */
-  public function testThreeLevelJoin() {
+  public function testThreeLevelJoin(): void {
     $this->createTestRecord('Activity', [
       'activity_type_id:name' => 'Phone Call',
     ]);
@@ -63,7 +63,7 @@ public function testThreeLevelJoin() {
     $this->assertCount(1, $results);
   }
 
-  public function testOptionalJoin() {
+  public function testOptionalJoin(): void {
     $contact1 = $this->createTestRecord('Contact');
     $contact2 = $this->createTestRecord('Contact');
 
@@ -91,7 +91,7 @@ public function testOptionalJoin() {
     $this->assertEquals($contact1['id'], $contacts[1]['id']);
   }
 
-  public function testRequiredJoin() {
+  public function testRequiredJoin(): void {
     $contact1 = $this->createTestRecord('Contact');
     $contact2 = $this->createTestRecord('Contact');
 
@@ -129,7 +129,7 @@ public function testRequiredJoin() {
     $this->assertEquals('1', $contacts[0]['phone.location_type_id']);
   }
 
-  public function testImplicitJoinOnExplicitJoin() {
+  public function testImplicitJoinOnExplicitJoin(): void {
     $contact1 = $this->createTestRecord('Contact');
     $this->createTestRecord('Address', [
       'contact_id' => $contact1['id'],
@@ -145,7 +145,7 @@ public function testImplicitJoinOnExplicitJoin() {
     $this->assertEquals('US', $contacts[0]['address.country_id.iso_code']);
   }
 
-  public function testExcludeJoin() {
+  public function testExcludeJoin(): void {
     $contact1 = $this->createTestRecord('Contact');
     $this->createTestRecord('Address', [
       'contact_id' => $contact1['id'],
@@ -158,7 +158,7 @@ public function testExcludeJoin() {
     $this->assertNotContains($contact1['id'], $contacts);
   }
 
-  public function testInvalidJoinAlias() {
+  public function testInvalidJoinAlias(): void {
     // Not allowed to use same alias as the base table
     try {
       Contact::get(FALSE)->addJoin('Address AS a')->execute();
@@ -192,7 +192,7 @@ public function testInvalidJoinAlias() {
     Contact::get(FALSE)->addJoin("Address AS $okAlias")->execute();
   }
 
-  public function testJoinToTheSameTableTwice() {
+  public function testJoinToTheSameTableTwice(): void {
     $cid1 = Contact::create(FALSE)
       ->addValue('first_name', 'Aaa')
       ->addChain('email1', Email::create()->setValues(['email' => 'yoohoo@yahoo.test', 'contact_id' => '$id', 'location_type_id:name' => 'Home']))
@@ -231,7 +231,7 @@ public function testJoinToTheSameTableTwice() {
     $this->assertEquals('1@test.test', $contacts[4]['primary_email.email']);
   }
 
-  public function testBridgeJoinTags() {
+  public function testBridgeJoinTags(): void {
     $tag1 = Tag::create(FALSE)
       ->addValue('name', uniqid('join1'))
       ->execute()
@@ -297,7 +297,7 @@ public function testBridgeJoinTags() {
     $this->assertEquals(1, (int) $reverse[$tag3]['contacts']);
   }
 
-  public function testBridgeJoinRelationshipContactActivity() {
+  public function testBridgeJoinRelationshipContactActivity(): void {
     $cid1 = Contact::create(FALSE)
       ->addValue('first_name', 'Aaa')
       ->addChain('activity', Activity::create()
@@ -416,7 +416,7 @@ public function testBridgeJoinRelationshipContactActivity() {
     }
   }
 
-  public function testJoinToEmployerId() {
+  public function testJoinToEmployerId(): void {
     $employer = Contact::create(FALSE)
       ->addValue('contact_type', 'Organization')
       ->addValue('organization_name', 'TesterCo')
@@ -445,7 +445,7 @@ public function testJoinToEmployerId() {
     $this->assertEquals('TesterCo', $emailGet['contact_id.employer_id.display_name']);
   }
 
-  public function testJoinWithExpression() {
+  public function testJoinWithExpression(): void {
 
     $contact1 = $this->createTestRecord('Contact');
     $contact2 = $this->createTestRecord('Contact');
@@ -465,7 +465,7 @@ public function testJoinWithExpression() {
     $this->assertEquals('654321', $contacts[0]['phone.phone']);
   }
 
-  public function testJoinCaseRoles() {
+  public function testJoinCaseRoles(): void {
     \CRM_Core_BAO_ConfigSetting::enableComponent('CiviCase');
 
     $contactID = $this->createTestRecord('Contact')['id'];
diff --git a/tests/phpunit/api/v4/Action/GetExtraFieldsTest.php b/tests/phpunit/api/v4/Action/GetExtraFieldsTest.php
index 32b680946d00..d3b5a5f4ce8a 100644
--- a/tests/phpunit/api/v4/Action/GetExtraFieldsTest.php
+++ b/tests/phpunit/api/v4/Action/GetExtraFieldsTest.php
@@ -30,7 +30,7 @@
  */
 class GetExtraFieldsTest extends Api4TestBase {
 
-  public function testGetFieldsByContactType() {
+  public function testGetFieldsByContactType(): void {
     $getFields = Contact::getFields(FALSE)->addSelect('name')->addWhere('type', '=', 'Field');
 
     $baseFields = array_column(\CRM_Contact_BAO_Contact::fields(), 'name');
@@ -61,7 +61,7 @@ public function testGetFieldsByContactType() {
     $this->assertContains('household_name', $householdFields);
   }
 
-  public function testGetOptionsAddress() {
+  public function testGetOptionsAddress(): void {
     $getFields = Address::getFields(FALSE)->addWhere('name', '=', 'state_province_id')->setLoadOptions(TRUE);
 
     $usOptions = $getFields->setValues(['country_id' => 1228])->execute()->first();
@@ -75,7 +75,7 @@ public function testGetOptionsAddress() {
     $this->assertContains('Alberta', $caOptions['options']);
   }
 
-  public function testGetFkFields() {
+  public function testGetFkFields(): void {
     $fields = \Civi\Api4\Participant::getFields()
       ->setLoadOptions(TRUE)
       ->addWhere('name', 'IN', ['event_id', 'event_id.created_id', 'contact_id.gender_id', 'event_id.created_id.sort_name'])
@@ -89,7 +89,7 @@ public function testGetFkFields() {
     $this->assertGreaterThan(1, count($fields['contact_id.gender_id']['options']));
   }
 
-  public function testGetTagsFromFilterField() {
+  public function testGetTagsFromFilterField(): void {
     $actTag = Tag::create(FALSE)
       ->addValue('name', uniqid('act'))
       ->addValue('used_for', 'civicrm_activity')
diff --git a/tests/phpunit/api/v4/Action/GetFieldsTest.php b/tests/phpunit/api/v4/Action/GetFieldsTest.php
index f7ea5d8c63b0..4da97acf33e8 100644
--- a/tests/phpunit/api/v4/Action/GetFieldsTest.php
+++ b/tests/phpunit/api/v4/Action/GetFieldsTest.php
@@ -39,7 +39,7 @@ public function setUp(): void {
     parent::setUp();
   }
 
-  public function testOptionsAreReturned() {
+  public function testOptionsAreReturned(): void {
     $fields = Contact::getFields(FALSE)
       ->execute()
       ->indexBy('name');
@@ -54,7 +54,7 @@ public function testOptionsAreReturned() {
     $this->assertFalse($fields['first_name']['options']);
   }
 
-  public function testContactGetFields() {
+  public function testContactGetFields(): void {
     $fields = Contact::getFields(FALSE)
       ->execute()
       ->indexBy('name');
@@ -67,7 +67,7 @@ public function testContactGetFields() {
     $this->assertEquals(['name', 'label', 'icon'], $fields['contact_sub_type']['suffixes']);
   }
 
-  public function testComponentFields() {
+  public function testComponentFields(): void {
     \CRM_Core_BAO_ConfigSetting::disableComponent('CiviCampaign');
     $fields = \Civi\Api4\Event::getFields()
       ->addWhere('name', 'CONTAINS', 'campaign')
@@ -80,7 +80,7 @@ public function testComponentFields() {
     $this->assertCount(1, $fields);
   }
 
-  public function testEmailFields() {
+  public function testEmailFields(): void {
     $getFields = Email::getFields(FALSE)
       ->setAction('get')
       ->execute()->indexBy('name');
@@ -94,7 +94,7 @@ public function testEmailFields() {
     $this->assertEquals('Email', $createFields['email']['input_type']);
   }
 
-  public function testInternalPropsAreHidden() {
+  public function testInternalPropsAreHidden(): void {
     // Public getFields should not contain @internal props
     $fields = Contact::getFields(FALSE)
       ->execute();
@@ -109,7 +109,7 @@ public function testInternalPropsAreHidden() {
     }
   }
 
-  public function testPrefetchDisabled() {
+  public function testPrefetchDisabled(): void {
     \CRM_Core_BAO_ConfigSetting::enableComponent('CiviContribute');
     \CRM_Core_BAO_ConfigSetting::enableComponent('CiviCampaign');
     Campaign::create()->setValues(['name' => 'Big Campaign', 'title' => 'Biggie'])->execute();
@@ -122,7 +122,7 @@ public function testPrefetchDisabled() {
     $this->assertEquals(['name', 'label'], $fields['campaign_id']['suffixes']);
   }
 
-  public function testRequiredAndNullableAndDeprecated() {
+  public function testRequiredAndNullableAndDeprecated(): void {
     $actFields = Activity::getFields(FALSE)
       ->setAction('create')
       ->execute()->indexBy('name');
@@ -136,7 +136,7 @@ public function testRequiredAndNullableAndDeprecated() {
     $this->assertTrue($actFields['phone_id']['deprecated']);
   }
 
-  public function testGetSuffixes() {
+  public function testGetSuffixes(): void {
     $actFields = Activity::getFields(FALSE)
       ->execute()->indexBy('name');
 
@@ -146,7 +146,7 @@ public function testGetSuffixes() {
     $this->assertEquals(['name', 'label', 'description', 'color'], $actFields['tags']['suffixes']);
   }
 
-  public function testDynamicFks() {
+  public function testDynamicFks(): void {
     $tagFields = EntityTag::getFields(FALSE)
       ->execute()->indexBy('name');
     $this->assertEmpty($tagFields['entity_id']['fk_entity']);
diff --git a/tests/phpunit/api/v4/Action/GetFromArrayTest.php b/tests/phpunit/api/v4/Action/GetFromArrayTest.php
index 90facdd3d35c..36ec00d5f27a 100644
--- a/tests/phpunit/api/v4/Action/GetFromArrayTest.php
+++ b/tests/phpunit/api/v4/Action/GetFromArrayTest.php
@@ -27,7 +27,7 @@
  */
 class GetFromArrayTest extends Api4TestBase {
 
-  public function testArrayGetWithLimit() {
+  public function testArrayGetWithLimit(): void {
     $result = MockArrayEntity::get()
       ->setOffset(2)
       ->setLimit(2)
@@ -40,7 +40,7 @@ public function testArrayGetWithLimit() {
     $this->assertCount(5, $result);
   }
 
-  public function testArrayGetWithSort() {
+  public function testArrayGetWithSort(): void {
     $result = MockArrayEntity::get()
       ->addOrderBy('field1', 'DESC')
       ->execute();
@@ -59,7 +59,7 @@ public function testArrayGetWithSort() {
     $this->assertEquals([3, 1, 2, 5, 4], array_column((array) $result, 'field1'));
   }
 
-  public function testArrayGetWithSelect() {
+  public function testArrayGetWithSelect(): void {
     $result = MockArrayEntity::get()
       ->addSelect('field1')
       ->addSelect('f*3')
@@ -85,7 +85,7 @@ public function testArrayGetWithSelect() {
     ], (array) $result);
   }
 
-  public function testArrayGetWithWhere() {
+  public function testArrayGetWithWhere(): void {
     $result = MockArrayEntity::get()
       ->addWhere('field2', '=', 'yack')
       ->execute();
@@ -168,7 +168,7 @@ public function testArrayGetWithWhere() {
     $this->assertEquals([1, 2, 5], array_column((array) $result, 'field1'));
   }
 
-  public function testArrayGetWithNestedWhereClauses() {
+  public function testArrayGetWithNestedWhereClauses(): void {
     $result = MockArrayEntity::get()
       ->addClause('OR', ['field2', 'LIKE', '%ra'], ['field2', 'LIKE', 'x ray'])
       ->execute();
diff --git a/tests/phpunit/api/v4/Action/IndexTest.php b/tests/phpunit/api/v4/Action/IndexTest.php
index dbd297e69786..7995a69359b2 100644
--- a/tests/phpunit/api/v4/Action/IndexTest.php
+++ b/tests/phpunit/api/v4/Action/IndexTest.php
@@ -26,7 +26,7 @@
  */
 class IndexTest extends Api4TestBase {
 
-  public function testIndex() {
+  public function testIndex(): void {
     // Results indexed by name
     $resultByName = civicrm_api4('Activity', 'getActions', [], 'name');
     $this->assertInstanceOf('Civi\Api4\Generic\Result', $resultByName);
@@ -40,7 +40,7 @@ public function testIndex() {
     $this->assertEquals($resultByName->first(), (array) $firstResult);
   }
 
-  public function testBadIndexInt() {
+  public function testBadIndexInt(): void {
     $error = '';
     try {
       civicrm_api4('Activity', 'getActions', [], 99);
@@ -51,7 +51,7 @@ public function testBadIndexInt() {
     $this->assertStringContainsString('not found', $error);
   }
 
-  public function testBadIndexString() {
+  public function testBadIndexString(): void {
     $error = '';
     try {
       civicrm_api4('Activity', 'getActions', [], 'xyz');
@@ -62,12 +62,12 @@ public function testBadIndexString() {
     $this->assertStringContainsString('not found', $error);
   }
 
-  public function testIndexWithSelect() {
+  public function testIndexWithSelect(): void {
     $result = civicrm_api4('Activity', 'getFields', ['select' => ['title'], 'where' => [['name', '=', 'subject']]], 'name');
     $this->assertEquals(['subject' => ['title' => 'Subject']], (array) $result);
   }
 
-  public function testArrayIndex() {
+  public function testArrayIndex(): void {
     // Non-associative
     $result = civicrm_api4('Activity', 'getFields', ['where' => [['name', '=', 'subject']]], ['name' => 'title']);
     $this->assertEquals(['subject' => 'Subject'], (array) $result);
diff --git a/tests/phpunit/api/v4/Action/IsPrimaryTest.php b/tests/phpunit/api/v4/Action/IsPrimaryTest.php
index 66551102a03a..854581ccee6d 100644
--- a/tests/phpunit/api/v4/Action/IsPrimaryTest.php
+++ b/tests/phpunit/api/v4/Action/IsPrimaryTest.php
@@ -35,7 +35,7 @@ class IsPrimaryTest extends Api4TestBase implements TransactionalInterface {
   /**
    * Test that creating a location entity or deleting one re-assigns is_primary correctly.
    */
-  public function testPrimaryHandling() {
+  public function testPrimaryHandling(): void {
     $contactID = $this->createTestRecord('Contact')['id'];
     // Create an entity of each type.
     Email::create()->setValues(['email' => 'b@example.com', 'contact_id' => $contactID])->execute();
diff --git a/tests/phpunit/api/v4/Action/NullValueTest.php b/tests/phpunit/api/v4/Action/NullValueTest.php
index 8dd0449f5afa..ec03641a25f9 100644
--- a/tests/phpunit/api/v4/Action/NullValueTest.php
+++ b/tests/phpunit/api/v4/Action/NullValueTest.php
@@ -35,7 +35,7 @@ public function setUp(): void {
     parent::setUp();
   }
 
-  public function testStringNull() {
+  public function testStringNull(): void {
     $contact = Contact::create(FALSE)
       ->addValue('first_name', 'Joseph')
       ->addValue('last_name', 'null')
@@ -47,7 +47,7 @@ public function testStringNull() {
     $this->assertSame('Joseph Null', $contact['display_name']);
   }
 
-  public function testSettingToNull() {
+  public function testSettingToNull(): void {
     $contact = Contact::create(FALSE)
       ->addValue('first_name', 'ILoveMy')
       ->addValue('last_name', 'LastName')
@@ -68,7 +68,7 @@ public function testSettingToNull() {
     $this->assertSame('ILoveMy', $contact['display_name']);
   }
 
-  public function testSaveWithReload() {
+  public function testSaveWithReload(): void {
     $contact = Contact::create(FALSE)
       ->addValue('first_name', 'Firsty')
       ->addValue('last_name', 'Lasty')
diff --git a/tests/phpunit/api/v4/Action/ReplaceTest.php b/tests/phpunit/api/v4/Action/ReplaceTest.php
index dabee7a19038..8199799696ae 100644
--- a/tests/phpunit/api/v4/Action/ReplaceTest.php
+++ b/tests/phpunit/api/v4/Action/ReplaceTest.php
@@ -49,7 +49,7 @@ public function setUp(): void {
     parent::setUp();
   }
 
-  public function testEmailReplace() {
+  public function testEmailReplace(): void {
     $cid1 = Contact::create()
       ->addValue('first_name', 'Lotsa')
       ->addValue('last_name', 'Emails')
@@ -105,7 +105,7 @@ public function testEmailReplace() {
     $this->assertEquals('nosomany@example.com', $c2email['email']);
   }
 
-  public function testCustomValueReplace() {
+  public function testCustomValueReplace(): void {
     $customGroup = CustomGroup::create(FALSE)
       ->addValue('title', 'replaceTest')
       ->addValue('extends', 'Contact')
diff --git a/tests/phpunit/api/v4/Action/RequiredFieldTest.php b/tests/phpunit/api/v4/Action/RequiredFieldTest.php
index 1bcb2b79a772..4a15166f1f4f 100644
--- a/tests/phpunit/api/v4/Action/RequiredFieldTest.php
+++ b/tests/phpunit/api/v4/Action/RequiredFieldTest.php
@@ -28,7 +28,7 @@
  */
 class RequiredFieldTest extends Api4TestBase implements TransactionalInterface {
 
-  public function testRequired() {
+  public function testRequired(): void {
     $msg = '';
     try {
       Event::create()->execute();
diff --git a/tests/phpunit/api/v4/Action/ResultTest.php b/tests/phpunit/api/v4/Action/ResultTest.php
index 6f107c49983e..8c1e800625b1 100644
--- a/tests/phpunit/api/v4/Action/ResultTest.php
+++ b/tests/phpunit/api/v4/Action/ResultTest.php
@@ -28,7 +28,7 @@
  */
 class ResultTest extends Api4TestBase implements TransactionalInterface {
 
-  public function testJsonSerialize() {
+  public function testJsonSerialize(): void {
     $result = Contact::getFields(FALSE)->addWhere('type', '=', 'Field')->execute();
     $json = json_encode($result);
     $this->assertStringStartsWith('[{"', $json);
@@ -42,7 +42,7 @@ public function testJsonSerialize() {
    * @see https://issues.civicrm.org/jira/browse/CRM-11532
    * @see https://lab.civicrm.org/dev/core/-/issues/1328
    */
-  public function testNoDataCorruptionThroughEncoding() {
+  public function testNoDataCorruptionThroughEncoding(): void {
 
     $original = 'hello < you';
     $result = Contact::create(FALSE)
diff --git a/tests/phpunit/api/v4/Action/SqlExpressionTest.php b/tests/phpunit/api/v4/Action/SqlExpressionTest.php
index 181cf29a6301..99a877005a29 100644
--- a/tests/phpunit/api/v4/Action/SqlExpressionTest.php
+++ b/tests/phpunit/api/v4/Action/SqlExpressionTest.php
@@ -29,7 +29,7 @@
  */
 class SqlExpressionTest extends Api4TestBase implements TransactionalInterface {
 
-  public function testSelectNull() {
+  public function testSelectNull(): void {
     Contact::create()->addValue('first_name', 'bob')->setCheckPermissions(FALSE)->execute();
     $result = Contact::get()
       ->addSelect('NULL AS nothing', 'NULL', 'NULL AS b*d char', 'first_name')
@@ -44,7 +44,7 @@ public function testSelectNull() {
     $this->assertArrayNotHasKey('b*d char', $result);
   }
 
-  public function testSelectNumbers() {
+  public function testSelectNumbers(): void {
     Contact::create()->addValue('first_name', 'bob')->setCheckPermissions(FALSE)->execute();
     $result = Contact::get()
       ->addSelect('first_name', 123, 45.678, '-55 AS neg')
@@ -58,7 +58,7 @@ public function testSelectNumbers() {
     $this->assertEquals('45.678', $result['45_678']);
   }
 
-  public function testSelectStrings() {
+  public function testSelectStrings(): void {
     Contact::create()->addValue('first_name', 'bob')->setCheckPermissions(FALSE)->execute();
     $result = Contact::get()
       ->addSelect('first_name')
@@ -73,7 +73,7 @@ public function testSelectStrings() {
     $this->assertEquals('can\'t "quote"', $result['quot']);
   }
 
-  public function testSelectAlias() {
+  public function testSelectAlias(): void {
     try {
       Contact::get()
         ->addSelect('first_name AS bob')
@@ -97,7 +97,7 @@ public function testSelectAlias() {
       ->execute();
   }
 
-  public function testSelectEquations() {
+  public function testSelectEquations(): void {
     $contact = Contact::create(FALSE)->addValue('first_name', 'bob')
       ->addChain('email', Email::create()->setValues(['email' => 'hello@example.com', 'contact_id' => '$id']))
       ->execute()->first();
diff --git a/tests/phpunit/api/v4/Action/SqlFunctionTest.php b/tests/phpunit/api/v4/Action/SqlFunctionTest.php
index d3ca2d9e1118..9bcdb8c8bffb 100644
--- a/tests/phpunit/api/v4/Action/SqlFunctionTest.php
+++ b/tests/phpunit/api/v4/Action/SqlFunctionTest.php
@@ -31,7 +31,7 @@
  */
 class SqlFunctionTest extends Api4TestBase implements TransactionalInterface {
 
-  public function testGetFunctions() {
+  public function testGetFunctions(): void {
     $functions = array_column(CoreUtil::getSqlFunctions(), NULL, 'name');
     $this->assertArrayHasKey('SUM', $functions);
     $this->assertArrayNotHasKey('', $functions);
@@ -43,7 +43,7 @@ public function testGetFunctions() {
     $this->assertEquals(12, $functions['MONTH']['options'][11]['id']);
   }
 
-  public function testGroupAggregates() {
+  public function testGroupAggregates(): void {
     $cid = Contact::create(FALSE)->addValue('first_name', 'bill')->execute()->first()['id'];
     Contribution::save(FALSE)
       ->setDefaults(['contact_id' => $cid, 'financial_type_id:name' => 'Donation'])
@@ -102,7 +102,7 @@ public function testGroupAggregates() {
     $this->assertContains('1, ' . $cid . ', 100.00', $agg['GROUP_CONCAT:financial_type_id_contact_id_total_amount']);
   }
 
-  public function testGroupHaving() {
+  public function testGroupHaving(): void {
     $cid = Contact::create(FALSE)->addValue('first_name', 'donor')->execute()->first()['id'];
     Contribution::save(FALSE)
       ->setDefaults(['contact_id' => $cid, 'financial_type_id' => 1])
@@ -152,7 +152,7 @@ public function testGroupHaving() {
     $this->assertEquals(400, $result[0]['SUM:total_amount']);
   }
 
-  public function testComparisonFunctions() {
+  public function testComparisonFunctions(): void {
     $cid = Contact::create(FALSE)
       ->addValue('first_name', 'hello')
       ->execute()->first()['id'];
@@ -212,7 +212,7 @@ public function testComparisonFunctions() {
     $this->assertEquals(456, $result[$aids[2]]['ifnull_duration_2']);
   }
 
-  public function testStringFunctions() {
+  public function testStringFunctions(): void {
     $sampleData = [
       ['first_name' => 'abc', 'middle_name' => 'Q', 'last_name' => 'tester1', 'source' => '123'],
     ];
@@ -240,7 +240,7 @@ public function testStringFunctions() {
     $this->assertEquals('est', $result['sub_last']);
   }
 
-  public function testDateFunctions() {
+  public function testDateFunctions(): void {
     $lastName = uniqid(__FUNCTION__);
     $sampleData = [
       ['first_name' => 'abc', 'last_name' => $lastName, 'birth_date' => '2009-11-11'],
@@ -285,7 +285,7 @@ public function testDateFunctions() {
     $this->assertEquals('Friday', $result[1]['day_name']);
   }
 
-  public function testIncorrectNumberOfArguments() {
+  public function testIncorrectNumberOfArguments(): void {
     try {
       Activity::get(FALSE)
         ->addSelect('IF(is_deleted) AS whoops')
@@ -317,7 +317,7 @@ public function testIncorrectNumberOfArguments() {
     }
   }
 
-  public function testCurrentDate() {
+  public function testCurrentDate(): void {
     $lastName = uniqid(__FUNCTION__);
     $sampleData = [
       ['first_name' => 'abc', 'last_name' => $lastName, 'birth_date' => 'now'],
@@ -343,7 +343,7 @@ public function testCurrentDate() {
     $this->assertCount(2, $result);
   }
 
-  public function testRandFunction() {
+  public function testRandFunction(): void {
     Contact::save(FALSE)
       ->setRecords(array_fill(0, 6, []))
       ->execute();
@@ -363,7 +363,7 @@ public function testRandFunction() {
     $this->assertGreaterThanOrEqual($result[4]['rand'], $result[5]['rand']);
   }
 
-  public function testDateInWhereClause() {
+  public function testDateInWhereClause(): void {
     $lastName = uniqid(__FUNCTION__);
     $sampleData = [
       ['first_name' => 'abc', 'last_name' => $lastName, 'birth_date' => '2009-11-11'],
diff --git a/tests/phpunit/api/v4/Action/UpdateContactTest.php b/tests/phpunit/api/v4/Action/UpdateContactTest.php
index 651c23ea87cc..63ac5999a64d 100644
--- a/tests/phpunit/api/v4/Action/UpdateContactTest.php
+++ b/tests/phpunit/api/v4/Action/UpdateContactTest.php
@@ -30,7 +30,7 @@
  */
 class UpdateContactTest extends Api4TestBase implements TransactionalInterface {
 
-  public function testUpdateWithIdInWhere() {
+  public function testUpdateWithIdInWhere(): void {
     $contactId = Contact::create(FALSE)
       ->addValue('first_name', 'Johann')
       ->addValue('last_name', 'Tester')
@@ -47,7 +47,7 @@ public function testUpdateWithIdInWhere() {
     $this->assertEquals('Tester', $contact['last_name']);
   }
 
-  public function testUpdateWithIdInValues() {
+  public function testUpdateWithIdInValues(): void {
     $contactId = Contact::create(FALSE)
       ->addValue('first_name', 'Bobby')
       ->addValue('last_name', 'Tester')
diff --git a/tests/phpunit/api/v4/Custom/BasicCustomFieldTest.php b/tests/phpunit/api/v4/Custom/BasicCustomFieldTest.php
index 582ee3a2c991..de375c0333ea 100644
--- a/tests/phpunit/api/v4/Custom/BasicCustomFieldTest.php
+++ b/tests/phpunit/api/v4/Custom/BasicCustomFieldTest.php
@@ -116,7 +116,7 @@ public function testWithSingleField(): void {
     $this->assertArrayNotHasKey('MyIndividualFields.FavColor', $contact);
   }
 
-  public function testWithTwoFields() {
+  public function testWithTwoFields(): void {
     $optionGroupCount = OptionGroup::get(FALSE)->selectRowCount()->execute()->count();
 
     // First custom set - use underscores in the names to ensure the API doesn't have a problem with them
@@ -269,7 +269,7 @@ public function testWithTwoFields() {
     $this->assertNotContains($contactId2, array_keys((array) $search));
   }
 
-  public function testRelationshipCacheCustomFields() {
+  public function testRelationshipCacheCustomFields(): void {
     $cgName = uniqid('RelFields');
 
     $customGroup = CustomGroup::create(FALSE)
@@ -340,7 +340,7 @@ public function testRelationshipCacheCustomFields() {
     $this->assertEquals('Buddy', $result["relative.$cgName.PetName"]);
   }
 
-  public function testMultipleJoinsToCustomTable() {
+  public function testMultipleJoinsToCustomTable(): void {
     $cgName = uniqid('My');
 
     CustomGroup::create(FALSE)
@@ -449,7 +449,7 @@ public function testPseudoConstantCreate(): void {
       ->execute();
   }
 
-  public function testUpdateWeights() {
+  public function testUpdateWeights(): void {
     $getValues = function($groupName) {
       return CustomField::get(FALSE)
         ->addWhere('custom_group_id.name', '=', $groupName)
@@ -560,7 +560,7 @@ public function testCustomDateFields(): void {
     $this->assertEquals('2025-06-11 12:15:30', $contact["$cgName.DateTime"]);
   }
 
-  public function testExtendsIdFilter() {
+  public function testExtendsIdFilter(): void {
     $fieldUnfiltered = \Civi\Api4\CustomGroup::getFields(FALSE)
       ->setLoadOptions(['id', 'name', 'grouping'])
       ->addWhere('name', '=', 'extends_entity_column_id')
@@ -587,7 +587,7 @@ public function testExtendsIdFilter() {
     $this->assertFalse($fieldFilteredByContact['options']);
   }
 
-  public function testExtendsMetadata() {
+  public function testExtendsMetadata(): void {
     $field = \Civi\Api4\CustomGroup::getFields(FALSE)
       ->setLoadOptions(['id', 'name', 'grouping'])
       ->addWhere('name', '=', 'extends')
@@ -634,7 +634,7 @@ public function testExtendsMetadata() {
     $this->assertArrayNotHasKey('Contribution_Fields.Dummy', $getFieldsWithoutTestType);
   }
 
-  public function testExtendsParticipantMetadata() {
+  public function testExtendsParticipantMetadata(): void {
     $event1 = $this->createTestRecord('Event', [
       'event_type_id:name' => 'Fundraiser',
       'title' => 'Test Fun Event',
diff --git a/tests/phpunit/api/v4/Custom/CreateCustomValueTest.php b/tests/phpunit/api/v4/Custom/CreateCustomValueTest.php
index 56b5fff6ab63..285f33395408 100644
--- a/tests/phpunit/api/v4/Custom/CreateCustomValueTest.php
+++ b/tests/phpunit/api/v4/Custom/CreateCustomValueTest.php
@@ -30,7 +30,7 @@
  */
 class CreateCustomValueTest extends CustomTestBase {
 
-  public function testGetWithCustomData() {
+  public function testGetWithCustomData(): void {
     $optionValues = ['r' => 'Red', 'g' => 'Green', 'b' => 'Blue'];
 
     $customGroup = CustomGroup::create(FALSE)
@@ -77,7 +77,7 @@ public function testGetWithCustomData() {
   /**
    * Test setting/getting a multivalue customfield with date+time
    */
-  public function testCustomDataWithDateTime() {
+  public function testCustomDataWithDateTime(): void {
     CustomGroup::create(FALSE)
       ->addValue('title', 'MyContactDateFields')
       ->addValue('name', 'MyContactDateFields')
diff --git a/tests/phpunit/api/v4/Custom/CreateWithOptionGroupTest.php b/tests/phpunit/api/v4/Custom/CreateWithOptionGroupTest.php
index c217f3f62fc1..ef9f1101f1ca 100644
--- a/tests/phpunit/api/v4/Custom/CreateWithOptionGroupTest.php
+++ b/tests/phpunit/api/v4/Custom/CreateWithOptionGroupTest.php
@@ -28,7 +28,7 @@
  */
 class CreateWithOptionGroupTest extends CustomTestBase {
 
-  public function testGetWithCustomData() {
+  public function testGetWithCustomData(): void {
     $group = uniqid('fava');
     $colorField = uniqid('colora');
     $foodField = uniqid('fooda');
@@ -94,7 +94,7 @@ public function testGetWithCustomData() {
     $this->assertEquals(50000, $result['FinancialStuff.Salary']);
   }
 
-  public function testWithCustomDataForMultipleContacts() {
+  public function testWithCustomDataForMultipleContacts(): void {
     $group = uniqid('favb');
     $colorField = uniqid('colorb');
     $foodField = uniqid('foodb');
diff --git a/tests/phpunit/api/v4/Custom/CustomContactRefTest.php b/tests/phpunit/api/v4/Custom/CustomContactRefTest.php
index 2d80b306dfb5..43af5042a698 100644
--- a/tests/phpunit/api/v4/Custom/CustomContactRefTest.php
+++ b/tests/phpunit/api/v4/Custom/CustomContactRefTest.php
@@ -28,7 +28,7 @@
  */
 class CustomContactRefTest extends CustomTestBase {
 
-  public function testGetWithJoin() {
+  public function testGetWithJoin(): void {
     $firstName = uniqid('fav');
 
     $customGroup = CustomGroup::create(FALSE)
@@ -118,7 +118,7 @@ public function testGetWithJoin() {
     $this->assertCount(2, $result);
   }
 
-  public function testCurrentUser() {
+  public function testCurrentUser(): void {
     $currentUser = $this->createLoggedInUser();
 
     $customGroup = CustomGroup::create(FALSE)
diff --git a/tests/phpunit/api/v4/Custom/CustomEntityReferenceTest.php b/tests/phpunit/api/v4/Custom/CustomEntityReferenceTest.php
index 1e47cf7d5602..3f34c1c0cc8e 100644
--- a/tests/phpunit/api/v4/Custom/CustomEntityReferenceTest.php
+++ b/tests/phpunit/api/v4/Custom/CustomEntityReferenceTest.php
@@ -30,7 +30,7 @@ class CustomEntityReferenceTest extends CustomTestBase {
   /**
    * Ensure custom fields of type EntityReference correctly apply filters
    */
-  public function testEntityReferenceCustomField() {
+  public function testEntityReferenceCustomField(): void {
     $subject = uniqid();
     CustomGroup::create()->setValues([
       'title' => 'EntityRefFields',
diff --git a/tests/phpunit/api/v4/Custom/CustomFieldAlterTest.php b/tests/phpunit/api/v4/Custom/CustomFieldAlterTest.php
index 96da07110a28..fa62a956a9cc 100644
--- a/tests/phpunit/api/v4/Custom/CustomFieldAlterTest.php
+++ b/tests/phpunit/api/v4/Custom/CustomFieldAlterTest.php
@@ -28,7 +28,7 @@
  */
 class CustomFieldAlterTest extends CustomTestBase {
 
-  public function testChangeSerialize() {
+  public function testChangeSerialize(): void {
     $contact = $this->createTestRecord('Contact');
 
     $customGroup = CustomGroup::create(FALSE)
diff --git a/tests/phpunit/api/v4/Custom/CustomFieldGetFieldsTest.php b/tests/phpunit/api/v4/Custom/CustomFieldGetFieldsTest.php
index 191c956d69d6..409f622ceaa9 100644
--- a/tests/phpunit/api/v4/Custom/CustomFieldGetFieldsTest.php
+++ b/tests/phpunit/api/v4/Custom/CustomFieldGetFieldsTest.php
@@ -50,7 +50,7 @@ public function tearDown(): void {
       ->execute();
   }
 
-  public function testDisabledFields() {
+  public function testDisabledFields(): void {
     // Create a custom group with one enabled and one disabled field
     CustomGroup::create(FALSE)
       ->addValue('extends', 'Activity')
@@ -81,7 +81,7 @@ public function testDisabledFields() {
     $this->assertNotContains('act_test_grp.disabled_field', $getFields);
   }
 
-  public function testCustomGetFieldsWithContactSubType() {
+  public function testCustomGetFieldsWithContactSubType(): void {
     ContactType::create(FALSE)
       ->addValue('name', $this->subTypeName)
       ->addValue('label', $this->subTypeName)
@@ -156,7 +156,7 @@ public function testCustomGetFieldsWithContactSubType() {
     $this->assertArrayHasKey('always.on', $groupFields);
   }
 
-  public function testCustomGetFieldsForParticipantSubTypes() {
+  public function testCustomGetFieldsForParticipantSubTypes(): void {
     $event1 = Event::create(FALSE)
       ->addValue('title', 'Test1')
       ->addValue('event_type_id:name', 'Meeting')
diff --git a/tests/phpunit/api/v4/Custom/CustomGroupACLTest.php b/tests/phpunit/api/v4/Custom/CustomGroupACLTest.php
index 2a6c006e4e1a..ab5c47324b10 100644
--- a/tests/phpunit/api/v4/Custom/CustomGroupACLTest.php
+++ b/tests/phpunit/api/v4/Custom/CustomGroupACLTest.php
@@ -38,7 +38,7 @@ public function tearDown(): void {
     \CRM_Core_DAO::executeQuery('TRUNCATE civicrm_acl_contact_cache');
   }
 
-  public function testViewEditCustomGroupACLs() {
+  public function testViewEditCustomGroupACLs(): void {
     $groups = ['readWrite' => 'Edit', 'readOnly' => 'View', 'superSecret' => NULL];
     $v3 = [];
 
diff --git a/tests/phpunit/api/v4/Custom/CustomGroupTest.php b/tests/phpunit/api/v4/Custom/CustomGroupTest.php
index a5cf4a77f9d1..52adc45555b3 100644
--- a/tests/phpunit/api/v4/Custom/CustomGroupTest.php
+++ b/tests/phpunit/api/v4/Custom/CustomGroupTest.php
@@ -26,7 +26,7 @@
  */
 class CustomGroupTest extends CustomTestBase {
 
-  public function testUpdateCustomGroup() {
+  public function testUpdateCustomGroup(): void {
     $customGroup1 = $this->createTestRecord('CustomGroup', [
       'extends' => 'Contribution',
       'weight' => 1,
@@ -51,7 +51,7 @@ public function testUpdateCustomGroup() {
     $this->assertEquals('Contribution', $groups[1]['extends']);
   }
 
-  public function testGetExtendsEntityColumnValuePseudoconstant() {
+  public function testGetExtendsEntityColumnValuePseudoconstant(): void {
     $activityTypeName = uniqid();
     $activityType = $this->createTestRecord('OptionValue', [
       'option_group_id:name' => 'activity_type',
diff --git a/tests/phpunit/api/v4/Custom/CustomProfileFieldTest.php b/tests/phpunit/api/v4/Custom/CustomProfileFieldTest.php
index ce7eaf9fd474..78c84e0241e6 100644
--- a/tests/phpunit/api/v4/Custom/CustomProfileFieldTest.php
+++ b/tests/phpunit/api/v4/Custom/CustomProfileFieldTest.php
@@ -27,7 +27,7 @@
  */
 class CustomProfileFieldTest extends CustomTestBase {
 
-  public function testExportProfileWithCustomFields() {
+  public function testExportProfileWithCustomFields(): void {
     $customGroup = CustomGroup::create(FALSE)
       ->addValue('title', 'ProfileGroup')
       ->addValue('extends', 'Individual')
diff --git a/tests/phpunit/api/v4/Custom/CustomValuePerformanceTest.php b/tests/phpunit/api/v4/Custom/CustomValuePerformanceTest.php
index 5d0a47348a68..a080e48aec28 100644
--- a/tests/phpunit/api/v4/Custom/CustomValuePerformanceTest.php
+++ b/tests/phpunit/api/v4/Custom/CustomValuePerformanceTest.php
@@ -31,7 +31,7 @@ class CustomValuePerformanceTest extends CustomTestBase {
 
   use QueryCounterTrait;
 
-  public function testQueryCount() {
+  public function testQueryCount(): void {
 
     $this->markTestIncomplete();
 
diff --git a/tests/phpunit/api/v4/Custom/CustomValueTest.php b/tests/phpunit/api/v4/Custom/CustomValueTest.php
index 2f754e4e48d4..1c81316d3ce4 100644
--- a/tests/phpunit/api/v4/Custom/CustomValueTest.php
+++ b/tests/phpunit/api/v4/Custom/CustomValueTest.php
@@ -32,7 +32,7 @@ class CustomValueTest extends CustomTestBase {
   /**
    * Test CustomValue::GetFields/Get/Create/Update/Replace/Delete
    */
-  public function testCRUD() {
+  public function testCRUD(): void {
     $optionValues = ['r' => 'Red', 'g' => 'Green', 'b' => 'Blue'];
 
     $group = uniqid('groupc');
@@ -282,7 +282,7 @@ public function testCRUD() {
    * @throws \CRM_Core_Exception
    * @throws \Civi\API\Exception\UnauthorizedException
    */
-  public function testEntityRefresh() {
+  public function testEntityRefresh(): void {
     $groupName = uniqid('groupc');
 
     $this->assertNotContains("Custom_$groupName", Entity::get()->execute()->column('name'));
diff --git a/tests/phpunit/api/v4/Custom/ExportCustomGroupTest.php b/tests/phpunit/api/v4/Custom/ExportCustomGroupTest.php
index 16638a498bb8..429b4dffb6f8 100644
--- a/tests/phpunit/api/v4/Custom/ExportCustomGroupTest.php
+++ b/tests/phpunit/api/v4/Custom/ExportCustomGroupTest.php
@@ -27,7 +27,7 @@
  */
 class ExportCustomGroupTest extends CustomTestBase {
 
-  public function testExportCustomGroupWithFieldOptions() {
+  public function testExportCustomGroupWithFieldOptions(): void {
     $optionValues = ['r' => 'Red', 'g' => 'Green', 'b' => 'Blue'];
 
     $customGroup = CustomGroup::create(FALSE)
diff --git a/tests/phpunit/api/v4/Custom/ExtendFromIndividualTest.php b/tests/phpunit/api/v4/Custom/ExtendFromIndividualTest.php
index 61ccb13e24be..da5e4f04cedb 100644
--- a/tests/phpunit/api/v4/Custom/ExtendFromIndividualTest.php
+++ b/tests/phpunit/api/v4/Custom/ExtendFromIndividualTest.php
@@ -28,7 +28,7 @@
  */
 class ExtendFromIndividualTest extends CustomTestBase {
 
-  public function testGetWithNonStandardExtends() {
+  public function testGetWithNonStandardExtends(): void {
 
     $customGroup = CustomGroup::create(FALSE)
       ->addValue('title', 'MyContactFields')
diff --git a/tests/phpunit/api/v4/Custom/FalseNotEqualsZeroTest.php b/tests/phpunit/api/v4/Custom/FalseNotEqualsZeroTest.php
index b3747d47ea79..2605286b4f32 100644
--- a/tests/phpunit/api/v4/Custom/FalseNotEqualsZeroTest.php
+++ b/tests/phpunit/api/v4/Custom/FalseNotEqualsZeroTest.php
@@ -28,7 +28,7 @@
  */
 class FalseNotEqualsZeroTest extends CustomTestBase {
 
-  public function testFalseNotEqualsZero() {
+  public function testFalseNotEqualsZero(): void {
 
     $customGroup = CustomGroup::create(FALSE)
       ->addValue('title', 'MyContactFields')
diff --git a/tests/phpunit/api/v4/Custom/PseudoconstantTest.php b/tests/phpunit/api/v4/Custom/PseudoconstantTest.php
index bf3a90bb641b..27fe1de01520 100644
--- a/tests/phpunit/api/v4/Custom/PseudoconstantTest.php
+++ b/tests/phpunit/api/v4/Custom/PseudoconstantTest.php
@@ -34,7 +34,7 @@
  */
 class PseudoconstantTest extends CustomTestBase {
 
-  public function testOptionValue() {
+  public function testOptionValue(): void {
     $cid = $this->createTestRecord('Contact', ['first_name', 'bill'])['id'];
     $subject = uniqid('subject');
     $this->createTestRecord('OptionValue', [
@@ -97,7 +97,7 @@ public function testOptionValue() {
     $this->assertTrue(is_numeric($act[0]['activity_type_id']));
   }
 
-  public function testAddressOptions() {
+  public function testAddressOptions(): void {
     $cid = $this->createTestRecord('Contact', ['first_name', 'addr'])['id'];
     $addressData = [
       [
@@ -146,7 +146,7 @@ public function testAddressOptions() {
     $this->assertEquals('Spain', $addr[2]['country_id:label']);
   }
 
-  public function testCustomOptions() {
+  public function testCustomOptions(): void {
     $technicolor = [
       ['id' => 'r', 'name' => 'red', 'label' => 'RED', 'color' => '#ff0000', 'description' => 'Red color', 'icon' => 'fa-red'],
       ['id' => 'g', 'name' => 'green', 'label' => 'GREEN', 'color' => '#00ff00', 'description' => 'Green color', 'icon' => 'fa-green'],
@@ -217,7 +217,7 @@ public function testCustomOptions() {
     $this->assertEquals($cid1, $result);
   }
 
-  public function testJoinOptions() {
+  public function testJoinOptions(): void {
     $cid1 = $this->createTestRecord('Contact', [
       'first_name' => 'Tom',
       'gender_id:label' => 'Male',
@@ -258,7 +258,7 @@ public function testJoinOptions() {
     $this->assertNull($emails[$cid3]['contact_id.gender_id:label']);
   }
 
-  public function testTagOptions() {
+  public function testTagOptions(): void {
     $tag = uniqid('tag');
     $this->createTestRecord('Tag', [
       'name' => $tag,
@@ -275,7 +275,7 @@ public function testTagOptions() {
     $this->assertEquals($tag, $options[$tag]['label']);
   }
 
-  public function testParticipantRole() {
+  public function testParticipantRole(): void {
     $event = $this->createTestRecord('Event');
     $contact = $this->createTestRecord('Contact');
     $participant = $this->createTestRecord('Participant', [
@@ -300,7 +300,7 @@ public function testParticipantRole() {
     $this->assertArrayNotHasKey($participant['id'], (array) $search2);
   }
 
-  public function testPreloadFalse() {
+  public function testPreloadFalse(): void {
     \CRM_Core_BAO_ConfigSetting::enableComponent('CiviContribute');
     \CRM_Core_BAO_ConfigSetting::enableComponent('CiviCampaign');
 
diff --git a/tests/phpunit/api/v4/Custom/UpdateCustomValueTest.php b/tests/phpunit/api/v4/Custom/UpdateCustomValueTest.php
index 84208ff92ef6..a789e8281040 100644
--- a/tests/phpunit/api/v4/Custom/UpdateCustomValueTest.php
+++ b/tests/phpunit/api/v4/Custom/UpdateCustomValueTest.php
@@ -29,7 +29,7 @@
  */
 class UpdateCustomValueTest extends CustomTestBase {
 
-  public function testGetWithCustomData() {
+  public function testGetWithCustomData(): void {
 
     $customGroup = CustomGroup::create(FALSE)
       ->addValue('title', 'MyContactFields')
diff --git a/tests/phpunit/api/v4/Entity/ActivityTest.php b/tests/phpunit/api/v4/Entity/ActivityTest.php
index 80529ed00adb..56625cdcea31 100644
--- a/tests/phpunit/api/v4/Entity/ActivityTest.php
+++ b/tests/phpunit/api/v4/Entity/ActivityTest.php
@@ -28,7 +28,7 @@
  */
 class ActivityTest extends Api4TestBase implements TransactionalInterface {
 
-  public function testActivityContactVirtualFields() {
+  public function testActivityContactVirtualFields(): void {
     $c = $this->saveTestRecords('Contact', ['records' => 5])->column('id');
 
     $sourceContactId = $c[2];
diff --git a/tests/phpunit/api/v4/Entity/AddressTest.php b/tests/phpunit/api/v4/Entity/AddressTest.php
index 5cb60b948720..dc9e9f74a225 100644
--- a/tests/phpunit/api/v4/Entity/AddressTest.php
+++ b/tests/phpunit/api/v4/Entity/AddressTest.php
@@ -40,7 +40,7 @@ public function setUp():void {
   /**
    * Check that 2 addresses for the same contact can't both be primary
    */
-  public function testPrimary() {
+  public function testPrimary(): void {
     $cid = Contact::create(FALSE)->addValue('first_name', uniqid())->execute()->single()['id'];
 
     $a1 = Address::create(FALSE)
@@ -66,7 +66,7 @@ public function testPrimary() {
     $this->assertTrue($addresses[1]['is_primary']);
   }
 
-  public function testSearchProximity() {
+  public function testSearchProximity(): void {
     $cid = $this->createTestRecord('Contact')['id'];
     $sampleData = [
       ['geo_code_1' => 20, 'geo_code_2' => 20],
@@ -91,7 +91,7 @@ public function testSearchProximity() {
     $this->assertNotContains($addreses[3], $result);
   }
 
-  public function testMasterAddressJoin() {
+  public function testMasterAddressJoin(): void {
     $contact = $this->createTestRecord('Contact');
     $master = $this->createTestRecord('Address', [
       'contact_id' => $contact['id'],
diff --git a/tests/phpunit/api/v4/Entity/CaseTest.php b/tests/phpunit/api/v4/Entity/CaseTest.php
index 27cd65f1a54c..7feff704de05 100644
--- a/tests/phpunit/api/v4/Entity/CaseTest.php
+++ b/tests/phpunit/api/v4/Entity/CaseTest.php
@@ -34,7 +34,7 @@ public function setUp(): void {
     \CRM_Core_BAO_ConfigSetting::enableComponent('CiviCase');
   }
 
-  public function testCreateUsingLoggedInUser() {
+  public function testCreateUsingLoggedInUser(): void {
     $uid = $this->createLoggedInUser();
 
     $contactID = $this->createTestRecord('Contact')['id'];
@@ -53,7 +53,7 @@ public function testCreateUsingLoggedInUser() {
     $this->assertEquals($contactID, $relationships[0]['contact_id_a']);
   }
 
-  public function testCgExtendsObjects() {
+  public function testCgExtendsObjects(): void {
     $this->createTestRecord('CaseType', [
       'title' => 'Test Case Type',
       'name' => 'test_case_type1',
diff --git a/tests/phpunit/api/v4/Entity/ContactJoinTest.php b/tests/phpunit/api/v4/Entity/ContactJoinTest.php
index f68ae8c7f200..bc499367fd92 100644
--- a/tests/phpunit/api/v4/Entity/ContactJoinTest.php
+++ b/tests/phpunit/api/v4/Entity/ContactJoinTest.php
@@ -31,7 +31,7 @@
  */
 class ContactJoinTest extends Api4TestBase {
 
-  public function testContactJoin() {
+  public function testContactJoin(): void {
     $contact = $this->createTestRecord('Contact', [
       'first_name' => uniqid(),
       'last_name' => uniqid(),
@@ -53,7 +53,7 @@ public function testContactJoin() {
     }
   }
 
-  public function testJoinToPCMWillReturnArray() {
+  public function testJoinToPCMWillReturnArray(): void {
     $contact = $this->createTestRecord('Contact', [
       'preferred_communication_method' => [1, 2, 3],
       'contact_type' => 'Individual',
@@ -70,7 +70,7 @@ public function testJoinToPCMWillReturnArray() {
     $this->assertCount(3, $fetchedContact["preferred_communication_method"]);
   }
 
-  public function testJoinToPCMOptionValueWillShowLabel() {
+  public function testJoinToPCMOptionValueWillShowLabel(): void {
     $options = OptionValue::get()
       ->addWhere('option_group_id:name', '=', 'preferred_communication_method')
       ->execute()
@@ -104,7 +104,7 @@ public function testJoinToPCMOptionValueWillShowLabel() {
     $this->assertEquals($labels, $fetchedContact['preferred_communication_method:label']);
   }
 
-  public function testCreateWithPrimaryAndBilling() {
+  public function testCreateWithPrimaryAndBilling(): void {
     $contact = $this->createTestRecord('Contact', [
       'email_primary.email' => 'a@test.com',
       'email_billing.email' => 'b@test.com',
@@ -131,7 +131,7 @@ public function testCreateWithPrimaryAndBilling() {
    * This is the same as testCreateWithPrimaryAndBilling, but the ambiguous
    * state "AK" is resolved within a different country "NG".
    */
-  public function testCreateWithPrimaryAndBilling_Nigeria() {
+  public function testCreateWithPrimaryAndBilling_Nigeria(): void {
     $contact = $this->createTestRecord('Contact', [
       'email_primary.email' => 'a@test.com',
       'email_billing.email' => 'b@test.com',
@@ -154,7 +154,7 @@ public function testCreateWithPrimaryAndBilling_Nigeria() {
     $this->assertEquals('b@test.com', $contact['email_billing.email']);
   }
 
-  public function testUpdateDeletePrimaryAndBilling() {
+  public function testUpdateDeletePrimaryAndBilling(): void {
     $contact = $this->createTestRecord('Contact', [
       'phone_primary.phone' => '12345',
       'phone_billing.phone' => '54321',
diff --git a/tests/phpunit/api/v4/Entity/ContactTypeTest.php b/tests/phpunit/api/v4/Entity/ContactTypeTest.php
index 11718ac18a00..9a82fff83156 100644
--- a/tests/phpunit/api/v4/Entity/ContactTypeTest.php
+++ b/tests/phpunit/api/v4/Entity/ContactTypeTest.php
@@ -31,7 +31,7 @@
  */
 class ContactTypeTest extends Api4TestBase implements TransactionalInterface {
 
-  public function testMenuItemWillBeCreatedAndDeleted() {
+  public function testMenuItemWillBeCreatedAndDeleted(): void {
     ContactType::create(FALSE)
       ->addValue('name', 'Tester')
       ->addValue('label', 'Tester')
@@ -56,7 +56,7 @@ public function testMenuItemWillBeCreatedAndDeleted() {
     $this->assertCount(0, Navigation::get(FALSE)->addWhere('name', '=', 'New Tester')->execute());
   }
 
-  public function testSubTypeWillBeRemovedFromExistingContacts() {
+  public function testSubTypeWillBeRemovedFromExistingContacts(): void {
     foreach (['TesterA', 'TesterB'] as $name) {
       ContactType::create(FALSE)
         ->addValue('name', $name)
@@ -79,7 +79,7 @@ public function testSubTypeWillBeRemovedFromExistingContacts() {
     $this->assertEquals(['TesterB'], Contact::get(FALSE)->addWhere('id', '=', $c2)->execute()->first()['contact_sub_type']);
   }
 
-  public function testGetReturnsFieldsAppropriateToEachContactType() {
+  public function testGetReturnsFieldsAppropriateToEachContactType(): void {
     $indiv = Contact::create()
       ->setValues(['first_name' => 'Joe', 'last_name' => 'Tester', 'prefix_id:label' => 'Dr.', 'contact_type' => 'Individual'])
       ->addChain('email', Email::create()->setValues(['contact_id' => '$id', 'email' => 'ind@example.com']))
diff --git a/tests/phpunit/api/v4/Entity/EntityTest.php b/tests/phpunit/api/v4/Entity/EntityTest.php
index 6a65f5fbb62f..1f60de79ce82 100644
--- a/tests/phpunit/api/v4/Entity/EntityTest.php
+++ b/tests/phpunit/api/v4/Entity/EntityTest.php
@@ -27,7 +27,7 @@
  */
 class EntityTest extends Api4TestBase {
 
-  public function testEntityGet() {
+  public function testEntityGet(): void {
     \CRM_Core_BAO_ConfigSetting::enableAllComponents();
     $result = Entity::get(FALSE)
       ->execute()
@@ -48,7 +48,7 @@ public function testEntityGet() {
     $this->assertEquals(['contact_id.sort_name', 'event_id.title'], $result['Participant']['search_fields']);
   }
 
-  public function testEntity() {
+  public function testEntity(): void {
     $result = Entity::getActions(FALSE)
       ->execute()
       ->indexBy('name');
@@ -58,7 +58,7 @@ public function testEntity() {
       "Entity entity has more than basic actions");
   }
 
-  public function testEntityComponent() {
+  public function testEntityComponent(): void {
     \CRM_Core_BAO_ConfigSetting::disableComponent('CiviEvent');
     $result = Entity::get(FALSE)
       ->execute()
diff --git a/tests/phpunit/api/v4/Entity/ExtensionTest.php b/tests/phpunit/api/v4/Entity/ExtensionTest.php
index 1619e544a6a8..f640008fe7b0 100644
--- a/tests/phpunit/api/v4/Entity/ExtensionTest.php
+++ b/tests/phpunit/api/v4/Entity/ExtensionTest.php
@@ -28,7 +28,7 @@
  */
 class ExtensionTest extends Api4TestBase implements TransactionalInterface {
 
-  public function testGet() {
+  public function testGet(): void {
     $moduleTest = Extension::get(FALSE)
       ->addWhere('key', '=', 'test.extension.manager.moduletest')
       ->execute()->single();
diff --git a/tests/phpunit/api/v4/Entity/GroupContactTest.php b/tests/phpunit/api/v4/Entity/GroupContactTest.php
index 3bde9ecea9a7..ffe83278952c 100644
--- a/tests/phpunit/api/v4/Entity/GroupContactTest.php
+++ b/tests/phpunit/api/v4/Entity/GroupContactTest.php
@@ -27,7 +27,7 @@
  */
 class GroupContactTest extends Api4TestBase {
 
-  public function testCount() {
+  public function testCount(): void {
     $contact = $this->createTestRecord('Contact');
     $group = $this->createTestRecord('Group');
 
diff --git a/tests/phpunit/api/v4/Entity/GroupTest.php b/tests/phpunit/api/v4/Entity/GroupTest.php
index a443113d0e40..f759d58d06f0 100644
--- a/tests/phpunit/api/v4/Entity/GroupTest.php
+++ b/tests/phpunit/api/v4/Entity/GroupTest.php
@@ -87,7 +87,7 @@ public function testSmartGroupCache(): void {
     $this->assertTrue($get[$smartGroup['id']]['cache_expired']);
   }
 
-  public function testCreate() {
+  public function testCreate(): void {
     $this->createLoggedInUser();
     \CRM_Core_Config::singleton()->userPermissionClass->permissions = [
       'access CiviCRM',
@@ -143,7 +143,7 @@ public function testCreate() {
       ->execute();
   }
 
-  public function testParentsInWhereClause() {
+  public function testParentsInWhereClause(): void {
     // Create 10 groups - at least 1 id will be 2-digit and contain the number 1
     $groups = $this->saveTestRecords('Group', [
       'records' => array_fill(0, 10, []),
@@ -180,7 +180,7 @@ public function testParentsInWhereClause() {
     $this->assertEquals($child3['id'], $found[0]['id']);
   }
 
-  public function testGetParents() {
+  public function testGetParents(): void {
     $parent1 = Group::create(FALSE)
       ->addValue('title', uniqid())
       ->execute()->single();
@@ -237,7 +237,7 @@ public function testGetParents() {
     $this->assertEquals($child2['title'], $joined[2]['child_group.title']);
   }
 
-  public function testAddRemoveParents() {
+  public function testAddRemoveParents(): void {
     $group1 = Group::create(FALSE)
       ->addValue('title', uniqid())
       ->execute()->single();
diff --git a/tests/phpunit/api/v4/Entity/MailingEvent.php b/tests/phpunit/api/v4/Entity/MailingEvent.php
index ad62716b8473..d0b2db70eef1 100644
--- a/tests/phpunit/api/v4/Entity/MailingEvent.php
+++ b/tests/phpunit/api/v4/Entity/MailingEvent.php
@@ -26,7 +26,7 @@
  */
 class MailingEventTest extends Api4TestBase implements TransactionalInterface {
 
-  public function testMailingStats() {
+  public function testMailingStats(): void {
     $cid1 = $this->createTestRecord('Contact')['id'];
     $cid2 = $this->createTestRecord('Contact')['id'];
     $eid1 = $this->createTestRecord('Email', ['contact_id' => $cid1])['id'];
diff --git a/tests/phpunit/api/v4/Entity/MembershipTest.php b/tests/phpunit/api/v4/Entity/MembershipTest.php
index b353e1ecbf07..c94f99f651af 100644
--- a/tests/phpunit/api/v4/Entity/MembershipTest.php
+++ b/tests/phpunit/api/v4/Entity/MembershipTest.php
@@ -29,7 +29,7 @@
  */
 class MembershipTest extends Api4TestBase implements TransactionalInterface {
 
-  public function testUpdateWeights() {
+  public function testUpdateWeights(): void {
     $getValues = function($domain) {
       return MembershipType::get(FALSE)
         ->addWhere('domain_id.name', '=', $domain)
diff --git a/tests/phpunit/api/v4/Entity/MessageTemplateTest.php b/tests/phpunit/api/v4/Entity/MessageTemplateTest.php
index ea5d06a48c21..c8a98b6f0c8c 100644
--- a/tests/phpunit/api/v4/Entity/MessageTemplateTest.php
+++ b/tests/phpunit/api/v4/Entity/MessageTemplateTest.php
@@ -45,7 +45,7 @@ class MessageTemplateTest extends Api4TestBase implements TransactionalInterface
   /**
    * Create/update a MessageTemplate with workflow_name and no corresponding workflow_id.
    */
-  public function testWorkflowName_clean() {
+  public function testWorkflowName_clean(): void {
     $create = civicrm_api4('MessageTemplate', 'create', [
       'values' => $this->baseTpl + ['workflow_name' => 'first', 'workflow_id' => NULL],
     ])->single();
@@ -63,7 +63,7 @@ public function testWorkflowName_clean() {
   /**
    * Create/update a MessageTemplate with workflow_name - a name which happens to have an older/corresponding workflow_id.
    */
-  public function testWorkflowName_legacyMatch() {
+  public function testWorkflowName_legacyMatch(): void {
     [$firstId, $secondId] = $this->createFirstSecond();
 
     $create = civicrm_api4('MessageTemplate', 'create', [
@@ -83,7 +83,7 @@ public function testWorkflowName_legacyMatch() {
   /**
    * Create/update a MessageTempalte with workflow_id. Ensure the newer workflow_name is set.
    */
-  public function testWorkflowId_legacyMatch() {
+  public function testWorkflowId_legacyMatch(): void {
     [$firstId, $secondId] = $this->createFirstSecond();
 
     $create = civicrm_api4('MessageTemplate', 'create', [
@@ -121,7 +121,7 @@ protected function createFirstSecond() {
   /**
    * Test save with no id
    */
-  public function testSaveNoId() {
+  public function testSaveNoId(): void {
     $saved = civicrm_api4('MessageTemplate', 'save', ['records' => [array_merge(['is_reserved' => 0], $this->baseTpl)]])->first();
     $this->assertDBQuery('My Template', 'SELECT msg_title FROM civicrm_msg_template WHERE id = %1', [1 => [$saved['id'], 'Int']]);
     $this->assertDBQuery('<p>My body as HTML</p>', 'SELECT msg_html FROM civicrm_msg_template WHERE id = %1', [1 => [$saved['id'], 'Int']]);
@@ -130,7 +130,7 @@ public function testSaveNoId() {
   /**
    * Test save with an explicit null id
    */
-  public function testSaveNullId() {
+  public function testSaveNullId(): void {
     $saved = civicrm_api4('MessageTemplate', 'save', ['records' => [array_merge(['id' => NULL, 'is_reserved' => 0], $this->baseTpl)]])->first();
     $this->assertDBQuery('My Template', 'SELECT msg_title FROM civicrm_msg_template WHERE id = %1', [1 => [$saved['id'], 'Int']]);
     $this->assertDBQuery('<p>My body as HTML</p>', 'SELECT msg_html FROM civicrm_msg_template WHERE id = %1', [1 => [$saved['id'], 'Int']]);
@@ -139,7 +139,7 @@ public function testSaveNullId() {
   /**
    * Test APIv4 calculated field master_id
    */
-  public function testMessageTemplateMasterID() {
+  public function testMessageTemplateMasterID(): void {
     \CRM_Core_Transaction::create(TRUE)->run(function(\CRM_Core_Transaction $tx) {
       $tx->rollback();
 
diff --git a/tests/phpunit/api/v4/Entity/NavigationTest.php b/tests/phpunit/api/v4/Entity/NavigationTest.php
index 390276f836af..5ce6d5ab7a70 100644
--- a/tests/phpunit/api/v4/Entity/NavigationTest.php
+++ b/tests/phpunit/api/v4/Entity/NavigationTest.php
@@ -27,7 +27,7 @@
  */
 class NavigationTest extends Api4TestBase implements TransactionalInterface {
 
-  public function testCreate() {
+  public function testCreate(): void {
     $created = Navigation::create(FALSE)
       ->addValue('permission', ['administer CiviCRM', 'access CiviCRM'])
       ->addValue('name', 'Test menu item')
diff --git a/tests/phpunit/api/v4/Entity/NoteTest.php b/tests/phpunit/api/v4/Entity/NoteTest.php
index f1fcd08f2393..dfdf46502b98 100644
--- a/tests/phpunit/api/v4/Entity/NoteTest.php
+++ b/tests/phpunit/api/v4/Entity/NoteTest.php
@@ -28,7 +28,7 @@
  */
 class NoteTest extends Api4TestBase implements TransactionalInterface {
 
-  public function testDeleteWithChildren() {
+  public function testDeleteWithChildren(): void {
     $c1 = $this->createTestRecord('Contact');
 
     $text = uniqid(__FUNCTION__, TRUE);
@@ -75,7 +75,7 @@ public function testDeleteWithChildren() {
     $this->assertCount(1, $existing);
   }
 
-  public function testJoinNotesFromContact() {
+  public function testJoinNotesFromContact(): void {
     $userId = $this->createLoggedInUser();
     $c1 = $this->createTestRecord('Contact');
     $c2 = $this->createTestRecord('Contact');
diff --git a/tests/phpunit/api/v4/Entity/OptionValueTest.php b/tests/phpunit/api/v4/Entity/OptionValueTest.php
index 3bc400188622..473e4aa262de 100644
--- a/tests/phpunit/api/v4/Entity/OptionValueTest.php
+++ b/tests/phpunit/api/v4/Entity/OptionValueTest.php
@@ -28,7 +28,7 @@
  */
 class OptionValueTest extends Api4TestBase implements TransactionalInterface {
 
-  public function testNullDefault() {
+  public function testNullDefault(): void {
     OptionGroup::create(FALSE)
       ->addValue('name', 'myTestGroup')
       ->addValue('title', 'myTestGroup')
@@ -55,7 +55,7 @@ public function testNullDefault() {
     $this->assertTrue(OptionValue::get(FALSE)->addWhere('id', '=', $defaultId)->execute()->first()['is_default']);
   }
 
-  public function testUpdateWeights() {
+  public function testUpdateWeights(): void {
     $getValues = function($groupName) {
       return OptionValue::get(FALSE)
         ->addWhere('option_group_id.name', '=', $groupName)
diff --git a/tests/phpunit/api/v4/Entity/ParticipantTest.php b/tests/phpunit/api/v4/Entity/ParticipantTest.php
index f7e91c841bd9..33f1c978b17d 100644
--- a/tests/phpunit/api/v4/Entity/ParticipantTest.php
+++ b/tests/phpunit/api/v4/Entity/ParticipantTest.php
@@ -39,7 +39,7 @@ public function setUp(): void {
     $this->cleanup($cleanup_params);
   }
 
-  public function testGetActions() {
+  public function testGetActions(): void {
     $result = Participant::getActions(FALSE)
       ->execute()
       ->indexBy('name');
@@ -51,7 +51,7 @@ public function testGetActions() {
     $this->assertStringContainsString($whereDescription, $getParams['where']['description']);
   }
 
-  public function testGet() {
+  public function testGet(): void {
     $rows = $this->getRowCount('civicrm_participant');
     if ($rows > 0) {
       $this->fail('Participant table must be empty');
diff --git a/tests/phpunit/api/v4/Entity/QueueTest.php b/tests/phpunit/api/v4/Entity/QueueTest.php
index 4252c9617f81..720dc537094c 100644
--- a/tests/phpunit/api/v4/Entity/QueueTest.php
+++ b/tests/phpunit/api/v4/Entity/QueueTest.php
@@ -50,7 +50,7 @@ protected function setUp(): void {
    * @throws \CRM_Core_Exception
    * @throws \Civi\API\Exception\UnauthorizedException
    */
-  public function testBasicLinearPolling() {
+  public function testBasicLinearPolling(): void {
     $queueName = 'QueueTest_' . md5(random_bytes(32)) . '_linear';
     $queue = \Civi::queue($queueName, [
       'type' => 'Sql',
@@ -104,7 +104,7 @@ public function testBasicLinearPolling() {
     $this->assertQueueStats(0, 0, 0, $queue);
   }
 
-  public function testBasicParallelPolling() {
+  public function testBasicParallelPolling(): void {
     $queueName = 'QueueTest_' . md5(random_bytes(32)) . '_parallel';
     $queue = \Civi::queue($queueName, ['type' => 'SqlParallel', 'runner' => 'task', 'error' => 'delete']);
     $this->assertQueueStats(0, 0, 0, $queue);
@@ -143,7 +143,7 @@ public function testBasicParallelPolling() {
    * @throws \CRM_Core_Exception
    * @throws \Civi\API\Exception\UnauthorizedException
    */
-  public function testBatchParallelPolling() {
+  public function testBatchParallelPolling(): void {
     $queueName = 'QueueTest_' . md5(random_bytes(32)) . '_parallel';
     \Civi::dispatcher()->addListener('hook_civicrm_queueRun_testStuff', [$this, 'onHookQueueRun']);
     $queue = \Civi::queue($queueName, [
@@ -189,7 +189,7 @@ function($item) {
     }
   }
 
-  public function testSelect() {
+  public function testSelect(): void {
     $queueName = 'QueueTest_' . md5(random_bytes(32)) . '_parallel';
     $queue = \Civi::queue($queueName, ['type' => 'SqlParallel', 'runner' => 'task', 'error' => 'delete']);
     $this->assertQueueStats(0, 0, 0, $queue);
@@ -206,7 +206,7 @@ public function testSelect() {
     $this->assertFalse(isset($first['run_as']));
   }
 
-  public function testSelectRunAs() {
+  public function testSelectRunAs(): void {
     $queueName = 'QueueTest_' . md5(random_bytes(32)) . '_select';
     $queue = \Civi::queue($queueName, ['type' => 'SqlParallel', 'runner' => 'task', 'error' => 'delete']);
     $this->assertQueueStats(0, 0, 0, $queue);
@@ -222,7 +222,7 @@ public function testSelectRunAs() {
     $this->assertEquals(['contactId' => 99, 'domainId' => 1], $first['run_as']);
   }
 
-  public function testEmptyPoll() {
+  public function testEmptyPoll(): void {
     $queueName = 'QueueTest_' . md5(random_bytes(32)) . '_linear';
     $queue = \Civi::queue($queueName, ['type' => 'Sql', 'runner' => 'task', 'error' => 'delete']);
     $this->assertQueueStats(0, 0, 0, $queue);
@@ -321,7 +321,7 @@ public function testRetryWithPoliteExhaustion(string $errorMode) {
    * Add a task. The task-running agent is a bit delinquent... so it forgets the first
    * few tasks. But the third one works!
    */
-  public function testRetryWithDelinquencyAndSuccess() {
+  public function testRetryWithDelinquencyAndSuccess(): void {
     $queueName = 'QueueTest_' . md5(random_bytes(32)) . '_linear';
     $queue = \Civi::queue($queueName, [
       'type' => 'Sql',
@@ -417,7 +417,7 @@ public function testRetryWithEventualFailure(string $errorMode) {
    * @throws \CRM_Core_Exception
    * @throws \Civi\API\Exception\UnauthorizedException
    */
-  public function testUserJobQueue_Completion() {
+  public function testUserJobQueue_Completion(): void {
     $queueName = 'QueueTest_' . md5(random_bytes(32)) . '_userjob';
 
     $firedQueueStatus = [];
@@ -473,7 +473,7 @@ public function testUserJobQueue_Completion() {
    * @throws \CRM_Core_Exception
    * @throws \Civi\API\Exception\UnauthorizedException
    */
-  public function testServiceQueue_NeverComplete() {
+  public function testServiceQueue_NeverComplete(): void {
     $queueName = 'QueueTest_' . md5(random_bytes(32)) . '_service';
 
     $firedQueueStatus = [];
diff --git a/tests/phpunit/api/v4/Entity/RecentItemTest.php b/tests/phpunit/api/v4/Entity/RecentItemTest.php
index 66856dbdb5b3..d0df7411e3d8 100644
--- a/tests/phpunit/api/v4/Entity/RecentItemTest.php
+++ b/tests/phpunit/api/v4/Entity/RecentItemTest.php
@@ -33,7 +33,7 @@ class RecentItemTest extends Api4TestBase implements TransactionalInterface {
   /**
    *
    */
-  public function testRecentContact() {
+  public function testRecentContact(): void {
     $cid = Contact::create(FALSE)
       ->addValue('first_name', 'Hello')
       ->execute()->single()['id'];
diff --git a/tests/phpunit/api/v4/Entity/RouteTest.php b/tests/phpunit/api/v4/Entity/RouteTest.php
index 1f2d2c121d55..c3cc55e53d60 100644
--- a/tests/phpunit/api/v4/Entity/RouteTest.php
+++ b/tests/phpunit/api/v4/Entity/RouteTest.php
@@ -27,7 +27,7 @@
  */
 class RouteTest extends Api4TestBase {
 
-  public function testGet() {
+  public function testGet(): void {
     $result = Route::get()->addWhere('path', '=', 'civicrm/admin')->execute();
     $this->assertEquals(1, $result->count());
 
diff --git a/tests/phpunit/api/v4/Entity/SavedSearchTest.php b/tests/phpunit/api/v4/Entity/SavedSearchTest.php
index 92d674d3d296..7c8c79d0db24 100644
--- a/tests/phpunit/api/v4/Entity/SavedSearchTest.php
+++ b/tests/phpunit/api/v4/Entity/SavedSearchTest.php
@@ -65,7 +65,7 @@ public function testContactSmartGroup(): void {
     $this->assertArrayNotHasKey($in['id'], (array) $outs);
   }
 
-  public function testEmailSmartGroup() {
+  public function testEmailSmartGroup(): void {
     $in = Contact::create(FALSE)->addValue('first_name', 'yep')->execute()->first();
     $out = Contact::create(FALSE)->addValue('first_name', 'nope')->execute()->first();
     $email = uniqid() . '@' . uniqid();
@@ -100,7 +100,7 @@ public function testEmailSmartGroup() {
     $this->assertArrayNotHasKey($in['id'], (array) $outs);
   }
 
-  public function testSmartGroupWithHaving() {
+  public function testSmartGroupWithHaving(): void {
     $in = Contact::create(FALSE)->addValue('first_name', 'yes')->addValue('last_name', 'siree')->execute()->first();
     $in2 = Contact::create(FALSE)->addValue('first_name', 'yessir')->addValue('last_name', 'ee')->execute()->first();
     $out = Contact::create(FALSE)->addValue('first_name', 'yess')->execute()->first();
@@ -139,7 +139,7 @@ public function testSmartGroupWithHaving() {
     $this->assertArrayNotHasKey($in2['id'], (array) $outs);
   }
 
-  public function testMultipleSmartGroups() {
+  public function testMultipleSmartGroups(): void {
     $inGroup = $outGroup = [];
     $inName = uniqid('inGroup');
     $outName = uniqid('outGroup');
diff --git a/tests/phpunit/api/v4/Entity/SettingTest.php b/tests/phpunit/api/v4/Entity/SettingTest.php
index f5f93763156c..38be23d4b909 100644
--- a/tests/phpunit/api/v4/Entity/SettingTest.php
+++ b/tests/phpunit/api/v4/Entity/SettingTest.php
@@ -28,7 +28,7 @@
  */
 class SettingTest extends Api4TestBase implements TransactionalInterface {
 
-  public function testSettingASetting() {
+  public function testSettingASetting(): void {
     $setting = Setting::set()->addValue('menubar_position', 'above-crm-container')->setCheckPermissions(FALSE)->execute()->first();
     $this->assertEquals('above-crm-container', $setting['value']);
     $setting = Setting::get()->addSelect('menubar_position')->setCheckPermissions(FALSE)->execute()->first();
@@ -40,7 +40,7 @@ public function testSettingASetting() {
     $this->assertEquals('over-cms-menu', $setting['value']);
   }
 
-  public function testInvalidSetting() {
+  public function testInvalidSetting(): void {
     $message = '';
     try {
       Setting::set()->addValue('not_a_real_setting!', 'hello')->setCheckPermissions(FALSE)->execute();
@@ -51,7 +51,7 @@ public function testInvalidSetting() {
     $this->assertStringContainsString('setting', $message);
   }
 
-  public function testSerailizedSetting() {
+  public function testSerailizedSetting(): void {
     $set = \Civi\Api4\Setting::set(FALSE)
       ->addValue('contact_edit_options:name', [
         'CommunicationPreferences',
@@ -75,7 +75,7 @@ public function testSerailizedSetting() {
   /**
    * Ensure settings work with the "index" mode.
    */
-  public function testSettingsWithIndexParam() {
+  public function testSettingsWithIndexParam(): void {
     $settings = civicrm_api4('Setting', 'get', [], ['name' => 'value']);
     $stringValues = FALSE;
     $arrayValues = FALSE;
@@ -96,7 +96,7 @@ public function testSettingsWithIndexParam() {
   /**
    * Make sure options load from getFields.
    */
-  public function testSettingGetFieldsOptions() {
+  public function testSettingGetFieldsOptions(): void {
     $setting = civicrm_api4('Setting', 'getFields', [
       'select' => ['options'],
       'loadOptions' => FALSE,
@@ -120,7 +120,7 @@ public function testSettingGetFieldsOptions() {
   /**
    * Ensure settings default values unserialize.
    */
-  public function testSettingUnserializeDefaults() {
+  public function testSettingUnserializeDefaults(): void {
     $setting = civicrm_api4('Setting', 'getFields', ['where' => [['name', '=', 'contact_view_options']]], 0);
     $this->assertTrue(is_array($setting['default']));
   }
diff --git a/tests/phpunit/api/v4/Entity/SubscriptionHistoryTest.php b/tests/phpunit/api/v4/Entity/SubscriptionHistoryTest.php
index 3a95c5ebb828..7d23ecc4d25e 100644
--- a/tests/phpunit/api/v4/Entity/SubscriptionHistoryTest.php
+++ b/tests/phpunit/api/v4/Entity/SubscriptionHistoryTest.php
@@ -28,7 +28,7 @@
  */
 class SubscriptionHistoryTest extends Api4TestBase {
 
-  public function testGet() {
+  public function testGet(): void {
     $contact = $this->createTestRecord('Contact');
     $group = $this->createTestRecord('Group');
     $timeAdded = time();
@@ -76,7 +76,7 @@ public function testGet() {
     $this->assertLessThanOrEqual(time(), strtotime($historyDeleted->single()['date']));
   }
 
-  public function testGetPermissions() {
+  public function testGetPermissions(): void {
     $this->createLoggedInUser();
 
     $contact = $this->createTestRecord('Contact');
diff --git a/tests/phpunit/api/v4/Entity/SystemRotateKeyTest.php b/tests/phpunit/api/v4/Entity/SystemRotateKeyTest.php
index c2022d366640..77cd65deba2c 100644
--- a/tests/phpunit/api/v4/Entity/SystemRotateKeyTest.php
+++ b/tests/phpunit/api/v4/Entity/SystemRotateKeyTest.php
@@ -40,7 +40,7 @@ public function setUp(): void {
     \CRM_Utils_Hook::singleton()->setHook('civicrm_cryptoRotateKey', [$this, 'onRotateKey']);
   }
 
-  public function testRekey() {
+  public function testRekey(): void {
     $result = \Civi\Api4\System::rotateKey(0)->setTag('UNIT-TEST')->execute();
     $this->assertEquals(2, count($result));
     $this->assertEquals('Updated field A using UNIT-TEST.', $result[0]['message']);
diff --git a/tests/phpunit/api/v4/Entity/SystemTest.php b/tests/phpunit/api/v4/Entity/SystemTest.php
index 3333a78e5290..fdab138225b4 100644
--- a/tests/phpunit/api/v4/Entity/SystemTest.php
+++ b/tests/phpunit/api/v4/Entity/SystemTest.php
@@ -30,7 +30,7 @@
  */
 class SystemTest extends Api4TestBase implements TransactionalInterface {
 
-  public function testSystemCheck() {
+  public function testSystemCheck(): void {
     $origEnv = \CRM_Core_Config::environment();
     $hooks = \CRM_Utils_Hook::singleton();
     $hooks->setHook('civicrm_check', [$this, 'hook_civicrm_check']);
diff --git a/tests/phpunit/api/v4/Entity/TagTest.php b/tests/phpunit/api/v4/Entity/TagTest.php
index 60640106d0d5..023d9c332257 100644
--- a/tests/phpunit/api/v4/Entity/TagTest.php
+++ b/tests/phpunit/api/v4/Entity/TagTest.php
@@ -29,7 +29,7 @@
  */
 class TagTest extends Api4TestBase implements TransactionalInterface {
 
-  public function testTagFilter() {
+  public function testTagFilter(): void {
     // Ensure bypassing permissions works correctly by giving none to the logged-in user
     $this->createLoggedInUser();
     \CRM_Core_Config::singleton()->userPermissionClass->permissions = [];
diff --git a/tests/phpunit/api/v4/Entity/ValidateValuesTest.php b/tests/phpunit/api/v4/Entity/ValidateValuesTest.php
index 0a95fcd1426a..1f447d6f1ef0 100644
--- a/tests/phpunit/api/v4/Entity/ValidateValuesTest.php
+++ b/tests/phpunit/api/v4/Entity/ValidateValuesTest.php
@@ -49,7 +49,7 @@ public function tearDown(): void {
    * @throws \CRM_Core_Exception
    * @throws \Civi\API\Exception\UnauthorizedException
    */
-  public function testHookData() {
+  public function testHookData(): void {
     $hookCount = 0;
 
     // Step 1: `create()` a record for Ms. Alice Alison.
@@ -131,7 +131,7 @@ public function testHookData() {
     $this->assertEquals(3, $hookCount);
   }
 
-  public function testRaiseError() {
+  public function testRaiseError(): void {
     $this->setValidator(function (ValidateValuesEvent $e) use (&$hookCount) {
       $this->assertWellFormedEvent($e);
       if ($e->getEntityName() !== 'Contact') {
diff --git a/tests/phpunit/api/v4/Entity/WordReplacementTest.php b/tests/phpunit/api/v4/Entity/WordReplacementTest.php
index 5bffeeaa77f9..71024b35e1d9 100644
--- a/tests/phpunit/api/v4/Entity/WordReplacementTest.php
+++ b/tests/phpunit/api/v4/Entity/WordReplacementTest.php
@@ -27,7 +27,7 @@
  */
 class WordReplacementTest extends Api4TestBase implements TransactionalInterface {
 
-  public function testDefaults() {
+  public function testDefaults(): void {
     $create = \Civi\Api4\WordReplacement::create(FALSE)
       ->addValue('find_word', 'Foo')
       ->addValue('replace_word', 'Bar')
diff --git a/tests/phpunit/api/v4/Query/Api4SelectQueryTest.php b/tests/phpunit/api/v4/Query/Api4SelectQueryTest.php
index ada14d805361..e4dfe0308dd9 100644
--- a/tests/phpunit/api/v4/Query/Api4SelectQueryTest.php
+++ b/tests/phpunit/api/v4/Query/Api4SelectQueryTest.php
@@ -28,7 +28,7 @@
  */
 class Api4SelectQueryTest extends Api4TestBase {
 
-  public function testManyToOneJoin() {
+  public function testManyToOneJoin(): void {
     $contact = $this->createTestRecord('Contact', [
       'first_name' => uniqid(),
       'last_name' => uniqid(),
diff --git a/tests/phpunit/api/v4/Query/OneToOneJoinTest.php b/tests/phpunit/api/v4/Query/OneToOneJoinTest.php
index a1601e7d713b..aee7a5b74c3f 100644
--- a/tests/phpunit/api/v4/Query/OneToOneJoinTest.php
+++ b/tests/phpunit/api/v4/Query/OneToOneJoinTest.php
@@ -30,7 +30,7 @@
  */
 class OneToOneJoinTest extends Api4TestBase implements TransactionalInterface {
 
-  public function testOneToOneJoin() {
+  public function testOneToOneJoin(): void {
     $armenianContact = Contact::create()
       ->addValue('first_name', 'Contact')
       ->addValue('last_name', 'One')
diff --git a/tests/phpunit/api/v4/Query/OptionValueJoinTest.php b/tests/phpunit/api/v4/Query/OptionValueJoinTest.php
index 3b3342ce129c..187cf48fca05 100644
--- a/tests/phpunit/api/v4/Query/OptionValueJoinTest.php
+++ b/tests/phpunit/api/v4/Query/OptionValueJoinTest.php
@@ -27,7 +27,7 @@
  */
 class OptionValueJoinTest extends Api4TestBase {
 
-  public function testCommunicationMethodJoin() {
+  public function testCommunicationMethodJoin(): void {
     $this->createTestRecord('Contact', [
       'preferred_communication_method' => 1,
     ]);
diff --git a/tests/phpunit/api/v4/Query/PermissionCheckTest.php b/tests/phpunit/api/v4/Query/PermissionCheckTest.php
index 3935f4c0d57b..ec2e7e22f116 100644
--- a/tests/phpunit/api/v4/Query/PermissionCheckTest.php
+++ b/tests/phpunit/api/v4/Query/PermissionCheckTest.php
@@ -45,7 +45,7 @@ public function tearDown(): void {
 
   /**
    */
-  public function testGatekeeperPermissions() {
+  public function testGatekeeperPermissions(): void {
     $config = \CRM_Core_Config::singleton();
     $config->userPermissionClass->permissions = [
       'access CiviCRM',
@@ -69,7 +69,7 @@ public function testGatekeeperPermissions() {
   /**
    * Tests that gatekeeper permissions are enforced for implicit joins
    */
-  public function testImplicitJoinPermissions() {
+  public function testImplicitJoinPermissions(): void {
     $config = \CRM_Core_Config::singleton();
     $config->userPermissionClass->permissions = [
       'access CiviCRM',
@@ -122,7 +122,7 @@ public function testImplicitJoinPermissions() {
   /**
    * Tests that gatekeeper permissions are enforced for explicit joins
    */
-  public function testExplicitJoinPermissions() {
+  public function testExplicitJoinPermissions(): void {
     $config = \CRM_Core_Config::singleton();
     $config->userPermissionClass->permissions = [
       'access CiviCRM',
diff --git a/tests/phpunit/api/v4/Query/SelectQueryMultiJoinTest.php b/tests/phpunit/api/v4/Query/SelectQueryMultiJoinTest.php
index f3b2ce370c5c..0ec3c072b21f 100644
--- a/tests/phpunit/api/v4/Query/SelectQueryMultiJoinTest.php
+++ b/tests/phpunit/api/v4/Query/SelectQueryMultiJoinTest.php
@@ -29,7 +29,7 @@
  */
 class SelectQueryMultiJoinTest extends Api4TestBase {
 
-  public function testManyToOneSelect() {
+  public function testManyToOneSelect(): void {
 
     $contact1 = $this->createTestRecord('Contact', [
       'first_name' => 'First',
diff --git a/tests/phpunit/api/v4/Service/Schema/SchemaMapperTest.php b/tests/phpunit/api/v4/Service/Schema/SchemaMapperTest.php
index e0fd73af9e4c..785034dc6299 100644
--- a/tests/phpunit/api/v4/Service/Schema/SchemaMapperTest.php
+++ b/tests/phpunit/api/v4/Service/Schema/SchemaMapperTest.php
@@ -29,7 +29,7 @@
  */
 class SchemaMapperTest extends Api4TestBase {
 
-  public function testWillHaveNoPathWithNoTables() {
+  public function testWillHaveNoPathWithNoTables(): void {
     $map = new SchemaMap();
     try {
       $map->getLink('foo', 'bar');
@@ -40,7 +40,7 @@ public function testWillHaveNoPathWithNoTables() {
     $this->assertStringContainsString('not found', $exception->getMessage());
   }
 
-  public function testWillHavePathWithSingleJump() {
+  public function testWillHavePathWithSingleJump(): void {
     $phoneTable = new Table('civicrm_phone');
     $locationTable = new Table('civicrm_location_type');
     $link = new Joinable('civicrm_location_type', 'id', 'location');
@@ -52,7 +52,7 @@ public function testWillHavePathWithSingleJump() {
     $this->assertNotEmpty($map->getLink('civicrm_phone', 'location'));
   }
 
-  public function testCircularReferenceWillNotBreakIt() {
+  public function testCircularReferenceWillNotBreakIt(): void {
     $contactTable = new Table('contact');
     $carTable = new Table('car');
     $carLink = new Joinable('car', 'id');
@@ -66,7 +66,7 @@ public function testCircularReferenceWillNotBreakIt() {
     $this->assertEmpty($map->getLink('contact', 'foo'));
   }
 
-  public function testCannotGoOverJoinLimit() {
+  public function testCannotGoOverJoinLimit(): void {
     $first = new Table('first');
     $second = new Table('second');
     $third = new Table('third');
diff --git a/tests/phpunit/api/v4/Spec/RequestSpecTest.php b/tests/phpunit/api/v4/Spec/RequestSpecTest.php
index 0f8e940ce438..2970b6fbb6f9 100644
--- a/tests/phpunit/api/v4/Spec/RequestSpecTest.php
+++ b/tests/phpunit/api/v4/Spec/RequestSpecTest.php
@@ -28,7 +28,7 @@
  */
 class RequestSpecTest extends Api4TestBase {
 
-  public function testRequiredFieldFetching() {
+  public function testRequiredFieldFetching(): void {
     $spec = new RequestSpec('Contact', 'get');
     $requiredField = new FieldSpec('name', 'Contact');
     $requiredField->setRequired(TRUE);
@@ -43,7 +43,7 @@ public function testRequiredFieldFetching() {
     $this->assertEquals('name', array_shift($requiredFields)->getName());
   }
 
-  public function testGettingFieldNames() {
+  public function testGettingFieldNames(): void {
     $spec = new RequestSpec('Contact', 'get');
     $nameField = new FieldSpec('name', 'Contact');
     $ageField = new FieldSpec('age', 'Contact', 'Integer');
diff --git a/tests/phpunit/api/v4/Spec/SpecFormatterTest.php b/tests/phpunit/api/v4/Spec/SpecFormatterTest.php
index d5d46f659475..6c6e33114429 100644
--- a/tests/phpunit/api/v4/Spec/SpecFormatterTest.php
+++ b/tests/phpunit/api/v4/Spec/SpecFormatterTest.php
@@ -42,7 +42,7 @@ public function testArrayToField($fieldData, $expectedName, $expectedType) {
     $this->assertEquals($expectedType, $field->getDataType());
   }
 
-  public function testCustomFieldWillBeReturned() {
+  public function testCustomFieldWillBeReturned(): void {
     $customGroupId = 1432;
     $customFieldId = 3333;
     $name = 'MyFancyField';
diff --git a/tests/phpunit/api/v4/Spec/SpecGathererTest.php b/tests/phpunit/api/v4/Spec/SpecGathererTest.php
index 4cfe0d9b30fd..04de1c46a4f5 100644
--- a/tests/phpunit/api/v4/Spec/SpecGathererTest.php
+++ b/tests/phpunit/api/v4/Spec/SpecGathererTest.php
@@ -36,7 +36,7 @@ class SpecGathererTest extends Api4TestBase {
   use TableDropperTrait;
   use OptionCleanupTrait;
 
-  public function testBasicFieldsGathering() {
+  public function testBasicFieldsGathering(): void {
     $gatherer = new SpecGatherer();
     $specs = $gatherer->getSpec('Contact', 'get', FALSE);
     $contactDAO = CoreUtil::getBAOFromApiName('Contact');
@@ -47,7 +47,7 @@ public function testBasicFieldsGathering() {
     $this->assertEmpty(array_diff_key($contactFieldNames, $specFieldNames));
   }
 
-  public function testWithSpecProvider() {
+  public function testWithSpecProvider(): void {
     $gather = new SpecGatherer();
 
     $provider = $this->prophesize(SpecProviderInterface::class);
diff --git a/tests/phpunit/api/v4/Utils/ArrayInsertionServiceTest.php b/tests/phpunit/api/v4/Utils/ArrayInsertionServiceTest.php
index ee9c86aa0aab..ddc7872b6188 100644
--- a/tests/phpunit/api/v4/Utils/ArrayInsertionServiceTest.php
+++ b/tests/phpunit/api/v4/Utils/ArrayInsertionServiceTest.php
@@ -27,7 +27,7 @@
  */
 class ArrayInsertionServiceTest extends Api4TestBase {
 
-  public function testInsertWillWork() {
+  public function testInsertWillWork(): void {
     $arr = [];
     $path = ['foo' => FALSE, 'bar' => FALSE];
     $inserter = new ArrayInsertionUtil();
@@ -42,7 +42,7 @@ public function testInsertWillWork() {
     $this->assertEquals($expected, $arr);
   }
 
-  public function testInsertionOfContactEmailLocation() {
+  public function testInsertionOfContactEmailLocation(): void {
     $contacts = [
       [
         'id' => 1,
diff --git a/tests/phpunit/api/v4/Utils/ReflectionUtilsTest.php b/tests/phpunit/api/v4/Utils/ReflectionUtilsTest.php
index 0f87b964f64d..82ec15afbbff 100644
--- a/tests/phpunit/api/v4/Utils/ReflectionUtilsTest.php
+++ b/tests/phpunit/api/v4/Utils/ReflectionUtilsTest.php
@@ -31,7 +31,7 @@ class ReflectionUtilsTest extends Api4TestBase {
   /**
    * Test that class annotations are returned across @inheritDoc
    */
-  public function testGetDocBlockForClass() {
+  public function testGetDocBlockForClass(): void {
     $grandChild = new MockV4ReflectionGrandchild();
     $reflection = new \ReflectionClass($grandChild);
     $doc = ReflectionUtils::getCodeDocs($reflection, NULL, ['entity' => "Test"]);
@@ -51,7 +51,7 @@ public function testGetDocBlockForClass() {
   /**
    * Test that property annotations are returned across @inheritDoc
    */
-  public function testGetDocBlockForProperty() {
+  public function testGetDocBlockForProperty(): void {
     $grandChild = new MockV4ReflectionGrandchild();
     $reflection = new \ReflectionClass($grandChild);
     $doc = ReflectionUtils::getCodeDocs($reflection->getProperty('foo'), 'Property');
@@ -109,7 +109,7 @@ public function testParseDocBlock($input, $expected) {
     $this->assertEquals($expected, ReflectionUtils::parseDocBlock($input));
   }
 
-  public function testIsMethodDeprecated() {
+  public function testIsMethodDeprecated(): void {
     $mockClass = 'api\v4\Mock\MockV4ReflectionGrandchild';
     $this->assertTrue(ReflectionUtils::isMethodDeprecated($mockClass, 'deprecatedFn'));
     $this->assertFalse(ReflectionUtils::isMethodDeprecated($mockClass, 'nonDeprecatedFn'));