diff --git a/apps/user_ldap/lib/Group_LDAP.php b/apps/user_ldap/lib/Group_LDAP.php
index 8fcb10cb850d0..b27bd1f8b6750 100644
--- a/apps/user_ldap/lib/Group_LDAP.php
+++ b/apps/user_ldap/lib/Group_LDAP.php
@@ -47,12 +47,13 @@
 use OC;
 use OC\Cache\CappedMemoryCache;
 use OC\ServerNotAvailableException;
+use OCP\Group\Backend\ABackend;
 use OCP\Group\Backend\IGetDisplayNameBackend;
 use OCP\Group\Backend\IDeleteGroupBackend;
 use OCP\GroupInterface;
 use Psr\Log\LoggerInterface;
 
-class Group_LDAP extends BackendUtility implements GroupInterface, IGroupLDAP, IGetDisplayNameBackend, IDeleteGroupBackend {
+class Group_LDAP extends ABackend implements GroupInterface, IGroupLDAP, IGetDisplayNameBackend, IDeleteGroupBackend {
 	protected $enabled = false;
 
 	/** @var CappedMemoryCache<string[]> $cachedGroupMembers array of users with gid as key */
@@ -61,10 +62,9 @@ class Group_LDAP extends BackendUtility implements GroupInterface, IGroupLDAP, I
 	protected CappedMemoryCache $cachedGroupsByMember;
 	/** @var CappedMemoryCache<string[]> $cachedNestedGroups array of groups with gid (DN) as key */
 	protected CappedMemoryCache $cachedNestedGroups;
-	/** @var GroupPluginManager */
-	protected $groupPluginManager;
-	/** @var LoggerInterface */
-	protected $logger;
+	protected GroupPluginManager $groupPluginManager;
+	protected LoggerInterface $logger;
+	protected Access $access;
 
 	/**
 	 * @var string $ldapGroupMemberAssocAttr contains the LDAP setting (in lower case) with the same name
@@ -72,7 +72,7 @@ class Group_LDAP extends BackendUtility implements GroupInterface, IGroupLDAP, I
 	protected $ldapGroupMemberAssocAttr;
 
 	public function __construct(Access $access, GroupPluginManager $groupPluginManager) {
-		parent::__construct($access);
+		$this->access = $access;
 		$filter = $this->access->connection->ldapGroupFilter;
 		$gAssoc = $this->access->connection->ldapGroupMemberAssocAttr;
 		if (!empty($filter) && !empty($gAssoc)) {
@@ -1203,7 +1203,7 @@ protected function filterValidGroups(array $listOfGroups): array {
 	 * Returns the supported actions as int to be
 	 * compared with GroupInterface::CREATE_GROUP etc.
 	 */
-	public function implementsActions($actions) {
+	public function implementsActions($actions): bool {
 		return (bool)((GroupInterface::COUNT_USERS |
 				GroupInterface::DELETE_GROUP |
 				$this->groupPluginManager->getImplementedActions()) & $actions);
@@ -1370,4 +1370,11 @@ public function getDisplayName(string $gid): string {
 
 		return '';
 	}
+
+	public function searchInGroup(string $gid, string $search = '', int $limit = -1, int $offset = 0): array {
+		if (!$this->enabled) {
+			return [];
+		}
+		return parent::searchInGroup($gid, $search, $limit, $offset);
+	}
 }
diff --git a/apps/user_ldap/lib/Group_Proxy.php b/apps/user_ldap/lib/Group_Proxy.php
index ea2fcce679c4a..1377c84656484 100644
--- a/apps/user_ldap/lib/Group_Proxy.php
+++ b/apps/user_ldap/lib/Group_Proxy.php
@@ -306,4 +306,8 @@ public function getDisplayName(string $gid): string {
 	public function getBackendName(): string {
 		return 'LDAP';
 	}
+
+	public function searchInGroup(string $gid, string $search = '', int $limit = -1, int $offset = 0): array {
+		return $this->handleRequest($gid, 'searchInGroup', [$gid, $search, $limit, $offset]);
+	}
 }
diff --git a/build/psalm-baseline.xml b/build/psalm-baseline.xml
index 1e27a2496c712..9d4c05305a49f 100644
--- a/build/psalm-baseline.xml
+++ b/build/psalm-baseline.xml
@@ -136,16 +136,6 @@
     </ParamNameMismatch>
   </file>
   <file src="apps/dav/lib/CalDAV/CalDavBackend.php">
-    <InvalidArgument occurrences="8">
-      <code>'\OCA\DAV\CalDAV\CalDavBackend::createCachedCalendarObject'</code>
-      <code>'\OCA\DAV\CalDAV\CalDavBackend::createSubscription'</code>
-      <code>'\OCA\DAV\CalDAV\CalDavBackend::deleteCachedCalendarObject'</code>
-      <code>'\OCA\DAV\CalDAV\CalDavBackend::deleteSubscription'</code>
-      <code>'\OCA\DAV\CalDAV\CalDavBackend::publishCalendar'</code>
-      <code>'\OCA\DAV\CalDAV\CalDavBackend::updateCachedCalendarObject'</code>
-      <code>'\OCA\DAV\CalDAV\CalDavBackend::updateShares'</code>
-      <code>'\OCA\DAV\CalDAV\CalDavBackend::updateSubscription'</code>
-    </InvalidArgument>
     <InvalidNullableReturnType occurrences="2">
       <code>array</code>
       <code>array</code>
@@ -161,16 +151,6 @@
     <RedundantCast occurrences="1">
       <code>(int)$calendarId</code>
     </RedundantCast>
-    <TooManyArguments occurrences="8">
-      <code>dispatch</code>
-      <code>dispatch</code>
-      <code>dispatch</code>
-      <code>dispatch</code>
-      <code>dispatch</code>
-      <code>dispatch</code>
-      <code>dispatch</code>
-      <code>dispatch</code>
-    </TooManyArguments>
     <UndefinedFunction occurrences="4">
       <code>Uri\split($principalUri)</code>
       <code>Uri\split($row['principaluri'])</code>
@@ -341,9 +321,6 @@
     </InvalidArgument>
   </file>
   <file src="apps/dav/lib/CardDAV/AddressBookImpl.php">
-    <InvalidArgument occurrences="1">
-      <code>$id</code>
-    </InvalidArgument>
     <InvalidScalarArgument occurrences="2">
       <code>$this-&gt;getKey()</code>
       <code>$this-&gt;getKey()</code>
@@ -358,16 +335,6 @@
     <FalsableReturnStatement occurrences="1">
       <code>false</code>
     </FalsableReturnStatement>
-    <InvalidArgument occurrences="3">
-      <code>'\OCA\DAV\CardDAV\CardDavBackend::createCard'</code>
-      <code>'\OCA\DAV\CardDAV\CardDavBackend::deleteCard'</code>
-      <code>'\OCA\DAV\CardDAV\CardDavBackend::updateCard'</code>
-    </InvalidArgument>
-    <TooManyArguments occurrences="3">
-      <code>dispatch</code>
-      <code>dispatch</code>
-      <code>dispatch</code>
-    </TooManyArguments>
     <TypeDoesNotContainType occurrences="1">
       <code>$addressBooks[$row['id']][$readOnlyPropertyName] === 0</code>
     </TypeDoesNotContainType>
@@ -889,7 +856,6 @@
     </RedundantCondition>
     <TypeDoesNotContainType occurrences="2">
       <code>get_class($res) === 'OpenSSLAsymmetricKey'</code>
-      <code>is_object($res)</code>
     </TypeDoesNotContainType>
   </file>
   <file src="apps/encryption/lib/Crypto/EncryptAll.php">
@@ -3366,16 +3332,13 @@
       <code>$result</code>
       <code>$this-&gt;copyFromStorage($sourceStorage, $sourceInternalPath . '/' . $file, $targetInternalPath . '/' . $file, false, $isRename)</code>
     </InvalidOperand>
-    <InvalidReturnStatement occurrences="6">
+    <InvalidReturnStatement occurrences="4">
       <code>$newUnencryptedSize</code>
       <code>$result</code>
-      <code>$stat</code>
       <code>$this-&gt;storage-&gt;file_get_contents($path)</code>
       <code>$this-&gt;storage-&gt;filesize($path)</code>
-      <code>$this-&gt;storage-&gt;getLocalFile($path)</code>
     </InvalidReturnStatement>
-    <InvalidReturnType occurrences="5">
-      <code>array</code>
+    <InvalidReturnType occurrences="3">
       <code>bool</code>
       <code>int</code>
       <code>string</code>
diff --git a/lib/private/Group/Database.php b/lib/private/Group/Database.php
index 7b7ee41def9b2..f445d1ad329c2 100644
--- a/lib/private/Group/Database.php
+++ b/lib/private/Group/Database.php
@@ -43,6 +43,9 @@
 use OCP\Group\Backend\ISetDisplayNameBackend;
 use OCP\Group\Backend\INamedBackend;
 use OCP\IDBConnection;
+use OCP\IUserManager;
+use OC\User\LazyUser;
+use OC\User\DisplayNameCache;
 
 /**
  * Class for group management in a SQL Database (e.g. MySQL, SQLite)
@@ -377,6 +380,58 @@ public function usersInGroup($gid, $search = '', $limit = -1, $offset = 0) {
 		return $users;
 	}
 
+	public function searchInGroup(string $gid, string $search = '', int $limit = -1, int $offset = 0): array {
+		$this->fixDI();
+
+		$query = $this->dbConn->getQueryBuilder();
+		if ($search !== '') {
+			$query->select('g.uid', 'u.displayname');
+		} else {
+			$query->select('g.uid');
+		}
+
+		$query->from('group_user', 'g')
+			->where($query->expr()->eq('gid', $query->createNamedParameter($gid)))
+			->orderBy('g.uid', 'ASC');
+
+		if ($search !== '') {
+			$query->leftJoin('g', 'users', 'u', $query->expr()->eq('g.uid', 'u.uid'))
+				->leftJoin('u', 'preferences', 'p', $query->expr()->andX(
+					$query->expr()->eq('p.userid', 'u.uid'),
+					$query->expr()->eq('p.appid', $query->expr()->literal('settings')),
+					$query->expr()->eq('p.configkey', $query->expr()->literal('email')))
+				)
+				// sqlite doesn't like re-using a single named parameter here
+				->andWhere(
+					$query->expr()->orX(
+						$query->expr()->ilike('g.uid', $query->createNamedParameter('%' . $this->dbConn->escapeLikeParameter($search) . '%')),
+						$query->expr()->ilike('u.displayname', $query->createNamedParameter('%' . $this->dbConn->escapeLikeParameter($search) . '%')),
+						$query->expr()->ilike('p.configvalue', $query->createNamedParameter('%' . $this->dbConn->escapeLikeParameter($search) . '%'))
+					)
+				)
+				->orderBy('u.uid_lower', 'ASC');
+		}
+
+		if ($limit !== -1) {
+			$query->setMaxResults($limit);
+		}
+		if ($offset !== 0) {
+			$query->setFirstResult($offset);
+		}
+
+		$result = $query->executeQuery();
+
+		$users = [];
+		$userManager = \OCP\Server::get(IUserManager::class);
+		$displayNameCache = \OCP\Server::get(DisplayNameCache::class);
+		while ($row = $result->fetch()) {
+			$users[$row['uid']] = new LazyUser($row['uid'], $displayNameCache, $userManager, $row['displayname'] ?? null);
+		}
+		$result->closeCursor();
+
+		return $users;
+	}
+
 	/**
 	 * get the number of all users matching the search string in a group
 	 * @param string $gid
diff --git a/lib/private/Group/Group.php b/lib/private/Group/Group.php
index 2ef4d2ee23fd3..dd792ce575828 100644
--- a/lib/private/Group/Group.php
+++ b/lib/private/Group/Group.php
@@ -238,18 +238,13 @@ public function removeUser($user) {
 	}
 
 	/**
-	 * search for users in the group by userid
-	 *
-	 * @param string $search
-	 * @param int $limit
-	 * @param int $offset
-	 * @return \OC\User\User[]
+	 * Search for users in the group by userid or display name
+	 * @return IUser[]
 	 */
-	public function searchUsers($search, $limit = null, $offset = null) {
+	public function searchUsers(string $search, ?int $limit = null, ?int $offset = null): array {
 		$users = [];
 		foreach ($this->backends as $backend) {
-			$userIds = $backend->usersInGroup($this->gid, $search, $limit, $offset);
-			$users += $this->getVerifiedUsers($userIds);
+			$users = array_merge($users, $backend->searchInGroup($this->gid, $search, $limit ?? -1, $offset ?? 0));
 			if (!is_null($limit) and $limit <= 0) {
 				return $users;
 			}
@@ -305,12 +300,12 @@ public function countDisabled() {
 	 * @param int $limit
 	 * @param int $offset
 	 * @return \OC\User\User[]
+	 * @deprecated 25.0.0 Use searchUsers instead (same implementation)
 	 */
 	public function searchDisplayName($search, $limit = null, $offset = null) {
 		$users = [];
 		foreach ($this->backends as $backend) {
-			$userIds = $backend->usersInGroup($this->gid, $search, $limit, $offset);
-			$users = $this->getVerifiedUsers($userIds);
+			$users = array_merge($users, $backend->searchInGroup($this->gid, $search, $limit ?? -1, $offset ?? 0));
 			if (!is_null($limit) and $limit <= 0) {
 				return array_values($users);
 			}
diff --git a/lib/private/User/LazyUser.php b/lib/private/User/LazyUser.php
index 8e93d6481ab20..089e6f4330f37 100644
--- a/lib/private/User/LazyUser.php
+++ b/lib/private/User/LazyUser.php
@@ -31,17 +31,27 @@ class LazyUser implements IUser {
 	private ?IUser $user = null;
 	private DisplayNameCache $displayNameCache;
 	private string $uid;
+	private ?string $displayName;
 	private IUserManager $userManager;
+	private ?UserInterface $backend;
 
-	public function __construct(string $uid, DisplayNameCache $displayNameCache, IUserManager $userManager) {
+	public function __construct(string $uid, DisplayNameCache $displayNameCache, IUserManager $userManager, ?string $displayName = null, ?UserInterface $backend = null) {
 		$this->displayNameCache = $displayNameCache;
 		$this->uid = $uid;
 		$this->userManager = $userManager;
+		$this->displayName = $displayName;
+		$this->backend = $backend;
 	}
 
 	private function getUser(): IUser {
 		if ($this->user === null) {
-			$this->user = $this->userManager->get($this->uid);
+			if ($this->backend) {
+				/** @var \OC\User\Manager $manager */
+				$manager = $this->userManager;
+				$this->user = $manager->getUserObject($this->uid, $this->backend);
+			} else {
+				$this->user = $this->userManager->get($this->uid);
+			}
 		}
 		/** @var IUser */
 		$user = $this->user;
@@ -53,6 +63,10 @@ public function getUID() {
 	}
 
 	public function getDisplayName() {
+		if ($this->displayName) {
+			return $this->displayName;
+		}
+
 		return $this->displayNameCache->getDisplayName($this->uid);
 	}
 
diff --git a/lib/private/User/Manager.php b/lib/private/User/Manager.php
index a6f5658532536..6ecfd5b01fc46 100644
--- a/lib/private/User/Manager.php
+++ b/lib/private/User/Manager.php
@@ -193,7 +193,7 @@ public function get($uid) {
 	 * @param bool $cacheUser If false the newly created user object will not be cached
 	 * @return \OC\User\User
 	 */
-	protected function getUserObject($uid, $backend, $cacheUser = true) {
+	public function getUserObject($uid, $backend, $cacheUser = true) {
 		if ($backend instanceof IGetRealUIDBackend) {
 			$uid = $backend->getRealUID($uid);
 		}
@@ -284,58 +284,53 @@ public function checkPasswordNoLogging($loginName, $password) {
 	}
 
 	/**
-	 * search by user id
+	 * Search by user id
 	 *
 	 * @param string $pattern
 	 * @param int $limit
 	 * @param int $offset
-	 * @return \OC\User\User[]
+	 * @return IUser[]
+	 * @deprecated since 25.0.0, use searchDisplayName instead
 	 */
 	public function search($pattern, $limit = null, $offset = null) {
 		$users = [];
+		$displayNameCache = \OCP\Server::get(DisplayNameCache::class);
 		foreach ($this->backends as $backend) {
 			$backendUsers = $backend->getUsers($pattern, $limit, $offset);
 			if (is_array($backendUsers)) {
 				foreach ($backendUsers as $uid) {
-					$users[$uid] = $this->getUserObject($uid, $backend);
+					$users[$uid] = new LazyUser($uid, $displayNameCache, $this, null, $backend);
 				}
 			}
 		}
 
-		uasort($users, function ($a, $b) {
-			/**
-			 * @var \OC\User\User $a
-			 * @var \OC\User\User $b
-			 */
+		uasort($users, function (IUser $a, IUser $b) {
 			return strcasecmp($a->getUID(), $b->getUID());
 		});
 		return $users;
 	}
 
 	/**
-	 * search by displayName
+	 * Search by displayName
 	 *
 	 * @param string $pattern
 	 * @param int $limit
 	 * @param int $offset
-	 * @return \OC\User\User[]
+	 * @return IUser[]
 	 */
 	public function searchDisplayName($pattern, $limit = null, $offset = null) {
 		$users = [];
+		$displayNameCache = \OCP\Server::get(DisplayNameCache::class);
 		foreach ($this->backends as $backend) {
 			$backendUsers = $backend->getDisplayNames($pattern, $limit, $offset);
 			if (is_array($backendUsers)) {
 				foreach ($backendUsers as $uid => $displayName) {
-					$users[] = $this->getUserObject($uid, $backend);
+					$users[] = new LazyUser($uid, $displayNameCache, $this, $displayName, $backend);
 				}
 			}
 		}
 
-		usort($users, function ($a, $b) {
-			/**
-			 * @var \OC\User\User $a
-			 * @var \OC\User\User $b
-			 */
+		usort($users, function (IUser $a, IUser $b) {
 			return strcasecmp($a->getDisplayName(), $b->getDisplayName());
 		});
 		return $users;
diff --git a/lib/public/Group/Backend/ABackend.php b/lib/public/Group/Backend/ABackend.php
index 2d611c27b4f38..f103ea5419bd8 100644
--- a/lib/public/Group/Backend/ABackend.php
+++ b/lib/public/Group/Backend/ABackend.php
@@ -65,4 +65,15 @@ public function implementsActions($actions): bool {
 
 		return (bool)($actions & $implements);
 	}
+
+	public function searchInGroup(string $gid, string $search = '', int $limit = -1, int $offset = 0): array {
+		// Default implementation for compatibility reasons
+		$displayNameCache = Server::get(DisplayNameCache::class);
+		$userManager = Server::get(IUserManager::class);
+		$users = [];
+		foreach ($this->usersInGroup($gid, $search, $limit, $offset) as $userId) {
+			$users[$userId] = new LazyUser($userId, $displayNameCache, $userManager);
+		}
+		return $users;
+	}
 }
diff --git a/lib/public/GroupInterface.php b/lib/public/GroupInterface.php
index f1765afed961e..597612840181e 100644
--- a/lib/public/GroupInterface.php
+++ b/lib/public/GroupInterface.php
@@ -107,13 +107,35 @@ public function getGroups($search = '', $limit = -1, $offset = 0);
 	public function groupExists($gid);
 
 	/**
-	 * get a list of all users in a group
+	 * @brief Get a list of user ids in a group matching the given search parameters.
+	 *
 	 * @param string $gid
 	 * @param string $search
 	 * @param int $limit
 	 * @param int $offset
 	 * @return array an array of user ids
 	 * @since 4.5.0
+	 * @deprecated 25.0.0 Use searchInGroup instead, for performance reasons
 	 */
 	public function usersInGroup($gid, $search = '', $limit = -1, $offset = 0);
+
+	/**
+	 * @brief Get a list of users matching the given search parameters.
+	 *
+	 * Implementations of this method should return lazy evaluated user objects and
+	 * preload if possible the display name.
+	 *
+	 * <code>
+	 * $users = $groupBackend->searchInGroup('admin', 'John', 10, 0);
+	 * </code>
+	 *
+	 * @param string $gid    The group id of the user we want to search
+	 * @param string $search The part of the display name or user id of the users we
+	 *                       want to search. This can be empty to get all the users.
+	 * @param int $limit     The limit of results
+	 * @param int $offset    The offset of the results
+	 * @return IUser[]
+	 * @since 25.0.0
+	 */
+	public function searchInGroup(string $gid, string $search = '', int $limit = -1, int $offset = 0): array;
 }
diff --git a/lib/public/IGroup.php b/lib/public/IGroup.php
index ba13359c472d9..ec26cc55b69ac 100644
--- a/lib/public/IGroup.php
+++ b/lib/public/IGroup.php
@@ -99,7 +99,7 @@ public function removeUser($user);
 	 * @return \OCP\IUser[]
 	 * @since 8.0.0
 	 */
-	public function searchUsers($search, $limit = null, $offset = null);
+	public function searchUsers(string $search, ?int $limit = null, ?int $offset = null): array;
 
 	/**
 	 * returns the number of users matching the search string
diff --git a/tests/lib/Group/GroupTest.php b/tests/lib/Group/GroupTest.php
index b85496620b83b..300ebe2b0fa5a 100644
--- a/tests/lib/Group/GroupTest.php
+++ b/tests/lib/Group/GroupTest.php
@@ -304,9 +304,9 @@ public function testSearchUsers() {
 		$group = new \OC\Group\Group('group1', [$backend], $this->dispatcher, $userManager);
 
 		$backend->expects($this->once())
-			->method('usersInGroup')
+			->method('searchInGroup')
 			->with('group1', '2')
-			->willReturn(['user2']);
+			->willReturn(['user2' => new \OC\User\User('user2', null, $this->dispatcher)]);
 
 		$users = $group->searchUsers('2');
 
@@ -326,13 +326,13 @@ public function testSearchUsersMultipleBackends() {
 		$group = new \OC\Group\Group('group1', [$backend1, $backend2], $this->dispatcher, $userManager);
 
 		$backend1->expects($this->once())
-			->method('usersInGroup')
+			->method('searchInGroup')
 			->with('group1', '2')
-			->willReturn(['user2']);
+			->willReturn(['user2' => new \OC\User\User('user2', null, $this->dispatcher)]);
 		$backend2->expects($this->once())
-			->method('usersInGroup')
+			->method('searchInGroup')
 			->with('group1', '2')
-			->willReturn(['user2']);
+			->willReturn(['user2' => new \OC\User\User('user2', null, $this->dispatcher)]);
 
 		$users = $group->searchUsers('2');
 
@@ -349,9 +349,9 @@ public function testSearchUsersLimitAndOffset() {
 		$group = new \OC\Group\Group('group1', [$backend], $this->dispatcher, $userManager);
 
 		$backend->expects($this->once())
-			->method('usersInGroup')
+			->method('searchInGroup')
 			->with('group1', 'user', 1, 1)
-			->willReturn(['user2']);
+			->willReturn(['user2' => new \OC\User\User('user2', null, $this->dispatcher)]);
 
 		$users = $group->searchUsers('user', 1, 1);
 
@@ -371,13 +371,13 @@ public function testSearchUsersMultipleBackendsLimitAndOffset() {
 		$group = new \OC\Group\Group('group1', [$backend1, $backend2], $this->dispatcher, $userManager);
 
 		$backend1->expects($this->once())
-			->method('usersInGroup')
+			->method('searchInGroup')
 			->with('group1', 'user', 2, 1)
-			->willReturn(['user2']);
+			->willReturn(['user2' => new \OC\User\User('user2', null, $this->dispatcher)]);
 		$backend2->expects($this->once())
-			->method('usersInGroup')
+			->method('searchInGroup')
 			->with('group1', 'user', 2, 1)
-			->willReturn(['user1']);
+			->willReturn(['user1' => new \OC\User\User('user1', null, $this->dispatcher)]);
 
 		$users = $group->searchUsers('user', 2, 1);
 
diff --git a/tests/lib/Group/ManagerTest.php b/tests/lib/Group/ManagerTest.php
index d689fd4eb7a49..5946144516350 100644
--- a/tests/lib/Group/ManagerTest.php
+++ b/tests/lib/Group/ManagerTest.php
@@ -24,6 +24,7 @@
 namespace Test\Group;
 
 use OC\Group\Database;
+use OC\User\User;
 use OC\User\Manager;
 use OCP\GroupInterface;
 use OCP\IUser;
@@ -87,6 +88,7 @@ private function getTestBackend($implementedActions = null) {
 				'createGroup',
 				'addToGroup',
 				'removeFromGroup',
+				'searchInGroup',
 			])
 			->getMock();
 		$backend->expects($this->any())
@@ -720,7 +722,7 @@ public function testDisplayNamesInGroupWithOneUserBackendWithLimitAndOffsetSpeci
 
 	public function testDisplayNamesInGroupWithOneUserBackendAndSearchEmpty() {
 		/**
-		 * @var \PHPUnit\Framework\MockObject\MockObject | \OC\Group\Backend $backend
+		 * @var \PHPUnit\Framework\MockObject\MockObject|\OC\Group\Backend $backend
 		 */
 		$backend = $this->getTestBackend();
 		$backend->expects($this->exactly(1))
@@ -729,22 +731,9 @@ public function testDisplayNamesInGroupWithOneUserBackendAndSearchEmpty() {
 			->willReturn(true);
 
 		$backend->expects($this->once())
-			->method('usersInGroup')
+			->method('searchInGroup')
 			->with('testgroup', '', -1, 0)
-			->willReturn(['user2', 'user33']);
-
-		$this->userManager->expects($this->any())
-			->method('get')
-			->willReturnCallback(function ($uid) {
-				switch ($uid) {
-					case 'user1': return $this->getTestUser('user1');
-					case 'user2': return $this->getTestUser('user2');
-					case 'user3': return $this->getTestUser('user3');
-					case 'user33': return $this->getTestUser('user33');
-					default:
-						return null;
-				}
-			});
+			->willReturn([$this->getTestUser('user2'), $this->getTestUser('user33')]);
 
 		$manager = new \OC\Group\Manager($this->userManager, $this->dispatcher, $this->logger);
 		$manager->addBackend($backend);
@@ -768,22 +757,9 @@ public function testDisplayNamesInGroupWithOneUserBackendAndSearchEmptyAndLimitS
 			->willReturn(true);
 
 		$backend->expects($this->once())
-			->method('usersInGroup')
+			->method('searchInGroup')
 			->with('testgroup', '', 1, 0)
-			->willReturn(['user2']);
-
-		$this->userManager->expects($this->any())
-			->method('get')
-			->willReturnCallback(function ($uid) {
-				switch ($uid) {
-					case 'user1': return $this->getTestUser('user1');
-					case 'user2': return $this->getTestUser('user2');
-					case 'user3': return $this->getTestUser('user3');
-					case 'user33': return $this->getTestUser('user33');
-					default:
-						return null;
-				}
-			});
+			->willReturn([new User('user2', null, $this->dispatcher)]);
 
 		$manager = new \OC\Group\Manager($this->userManager, $this->dispatcher, $this->logger);
 		$manager->addBackend($backend);
@@ -807,22 +783,9 @@ public function testDisplayNamesInGroupWithOneUserBackendAndSearchEmptyAndLimitA
 			->willReturn(true);
 
 		$backend->expects($this->once())
-			->method('usersInGroup')
+			->method('searchInGroup')
 			->with('testgroup', '', 1, 1)
-			->willReturn(['user33']);
-
-		$this->userManager->expects($this->any())
-			->method('get')
-			->willReturnCallback(function ($uid) {
-				switch ($uid) {
-					case 'user1': return $this->getTestUser('user1');
-					case 'user2': return $this->getTestUser('user2');
-					case 'user3': return $this->getTestUser('user3');
-					case 'user33': return $this->getTestUser('user33');
-					default:
-						return null;
-				}
-			});
+			->willReturn([$this->getTestUser('user33')]);
 
 		$manager = new \OC\Group\Manager($this->userManager, $this->dispatcher, $this->logger);
 		$manager->addBackend($backend);
diff --git a/tests/lib/Util/Group/Dummy.php b/tests/lib/Util/Group/Dummy.php
index 3735a5e1167e8..2d86e45cfc164 100644
--- a/tests/lib/Util/Group/Dummy.php
+++ b/tests/lib/Util/Group/Dummy.php
@@ -29,12 +29,18 @@
 
 namespace Test\Util\Group;
 
-use OC\Group\Backend;
+use Test\Util\User\Dummy as DummyUser;
+use OCP\Group\Backend\ABackend;
+use OCP\Group\Backend\IDeleteGroupBackend;
+use OCP\Group\Backend\IAddToGroupBackend;
+use OCP\Group\Backend\IRemoveFromGroupBackend;
+use OCP\Group\Backend\ICreateGroupBackend;
+use OCP\Group\Backend\ICountUsersBackend;
 
 /**
- * dummy group backend, does not keep state, only for testing use
+ * Dummy group backend, does not keep state, only for testing use
  */
-class Dummy extends Backend {
+class Dummy extends ABackend implements ICreateGroupBackend, IDeleteGroupBackend, IAddToGroupBackend, IRemoveFromGroupBackend, ICountUsersBackend {
 	private $groups = [];
 	/**
 	 * Try to create a new group
@@ -44,7 +50,7 @@ class Dummy extends Backend {
 	 * Tries to create a new group. If the group name already exists, false will
 	 * be returned.
 	 */
-	public function createGroup($gid) {
+	public function createGroup(string $gid): bool {
 		if (!isset($this->groups[$gid])) {
 			$this->groups[$gid] = [];
 			return true;
@@ -60,7 +66,7 @@ public function createGroup($gid) {
 	 *
 	 * Deletes a group and removes it from the group_user-table
 	 */
-	public function deleteGroup($gid) {
+	public function deleteGroup(string $gid): bool {
 		if (isset($this->groups[$gid])) {
 			unset($this->groups[$gid]);
 			return true;
@@ -93,7 +99,7 @@ public function inGroup($uid, $gid) {
 	 *
 	 * Adds a user to a group.
 	 */
-	public function addToGroup($uid, $gid) {
+	public function addToGroup(string $uid, string $gid): bool {
 		if (isset($this->groups[$gid])) {
 			if (array_search($uid, $this->groups[$gid]) === false) {
 				$this->groups[$gid][] = $uid;
@@ -114,7 +120,7 @@ public function addToGroup($uid, $gid) {
 	 *
 	 * removes the user from a group.
 	 */
-	public function removeFromGroup($uid, $gid) {
+	public function removeFromGroup(string $uid, string $gid): bool {
 		if (isset($this->groups[$gid])) {
 			if (($index = array_search($uid, $this->groups[$gid])) !== false) {
 				unset($this->groups[$gid][$index]);
@@ -192,6 +198,25 @@ public function usersInGroup($gid, $search = '', $limit = -1, $offset = 0) {
 		}
 	}
 
+	public function searchInGroup(string $gid, string $search = '', int $limit = -1, int $offset = 0): array {
+		if (isset($this->groups[$gid])) {
+			if (empty($search)) {
+				$length = $limit < 0 ? null : $limit;
+				$users = array_slice($this->groups[$gid], $offset, $length);
+				return array_map(fn ($user) => new DummyUser($user, ''));
+			}
+			$result = [];
+			foreach ($this->groups[$gid] as $user) {
+				if (stripos($user, $search) !== false) {
+					$result[] = new DummyUser($user, '');
+				}
+			}
+			return $result;
+		} else {
+			return [];
+		}
+	}
+
 	/**
 	 * get the number of all users in a group
 	 * @param string $gid
@@ -200,7 +225,7 @@ public function usersInGroup($gid, $search = '', $limit = -1, $offset = 0) {
 	 * @param int $offset
 	 * @return int
 	 */
-	public function countUsersInGroup($gid, $search = '', $limit = -1, $offset = 0) {
+	public function countUsersInGroup(string $gid, string $search = ''): int {
 		if (isset($this->groups[$gid])) {
 			if (empty($search)) {
 				return count($this->groups[$gid]);
@@ -213,5 +238,10 @@ public function countUsersInGroup($gid, $search = '', $limit = -1, $offset = 0)
 			}
 			return $count;
 		}
+		return 0;
+	}
+
+	public function groupExists($gid) {
+		return isset($this->groups[$gid]);
 	}
 }