diff --git a/CRM/Extension/Container/Basic.php b/CRM/Extension/Container/Basic.php
index 42277242767a..3251722565e7 100644
--- a/CRM/Extension/Container/Basic.php
+++ b/CRM/Extension/Container/Basic.php
@@ -82,6 +82,14 @@ class CRM_Extension_Container_Basic implements CRM_Extension_Container_Interface
    */
   public $relUrls = FALSE;
 
+  /**
+   * @var array
+   *   Array(function(CRM_Extension_Info $info): bool)
+   *   List of callables which determine whether an extension is visible.
+   *   Each function returns TRUE if the extension should be visible.
+   */
+  protected $filters = [];
+
   /**
    * @param string $baseDir
    *   Local path to the container.
@@ -216,7 +224,16 @@ protected function getRelPaths() {
             CRM_Core_Error::debug_log_message("Parse error in extension: " . $e->getMessage());
             continue;
           }
-          $this->relPaths[$info->key] = $relPath;
+          $visible = TRUE;
+          foreach ($this->filters as $filter) {
+            if (!$filter($info)) {
+              $visible = FALSE;
+              break;
+            }
+          }
+          if ($visible) {
+            $this->relPaths[$info->key] = $relPath;
+          }
         }
         if ($this->cache) {
           $this->cache->set($this->cacheKey, $this->relPaths);
@@ -259,6 +276,20 @@ protected function getRelUrls() {
     return $this->relUrls;
   }
 
+  /**
+   * Register a filter which determine whether a copy of an extension
+   * appears as available.
+   *
+   * @param callable $callable
+   *   function(CRM_Extension_Info $info): bool
+   *   Each function returns TRUE if the extension should be visible.
+   * @return $this
+   */
+  public function addFilter($callable) {
+    $this->filters[] = $callable;
+    return $this;
+  }
+
   /**
    * Convert a list of relative paths to relative URLs.
    *
diff --git a/CRM/Extension/System.php b/CRM/Extension/System.php
index b3157ffd5722..f9665524d9b9 100644
--- a/CRM/Extension/System.php
+++ b/CRM/Extension/System.php
@@ -155,6 +155,12 @@ public function getFullContainer() {
         }
       }
 
+      if (!defined('CIVICRM_TEST')) {
+        foreach ($containers as $container) {
+          $container->addFilter([__CLASS__, 'isNotTestExtension']);
+        }
+      }
+
       $this->fullContainer = new CRM_Extension_Container_Collection($containers, $this->getCache(), 'full');
     }
     return $this->fullContainer;
@@ -302,6 +308,10 @@ public static function getCompatibilityInfo() {
     return Civi::$statics[__CLASS__]['compatibility'];
   }
 
+  public static function isNotTestExtension(CRM_Extension_Info $info) {
+    return (bool) !preg_match('/^test\./', $info->key);
+  }
+
   /**
    * Take an extension's raw XML info and add information about the
    * extension's status on the local system.