diff --git a/cache/tests/fixtures/lib.php b/cache/tests/fixtures/lib.php
index 7b05b2e734a..1bdf7d753c6 100644
--- a/cache/tests/fixtures/lib.php
+++ b/cache/tests/fixtures/lib.php
@@ -536,6 +536,11 @@ class cache_phpunit_factory extends cache_factory {
         parent::disable();
     }
 
+    /**
+     * @var bool Whether the warning notice about alternative cache store used has been displayed.
+     */
+    protected $altcachestorenotice = false;
+
     /**
      * Creates a store instance given its name and configuration.
      *
@@ -559,7 +564,15 @@ class cache_phpunit_factory extends cache_factory {
                     return $instance;
                 }
             }
+
+            // Notify user that alternative store is being used, so action can be taken.
+            if (!$this->altcachestorenotice) {
+                echo PHP_EOL . "++ WARNING: " . 'Failed to use "' . $details['plugin'] . '" cache store, alt "' .
+                    $details['alt']['plugin'] . '" cache store is used.' . PHP_EOL . PHP_EOL;
+                $this->altcachestorenotice = true;
+            }
             $details = $details['alt'];
+            $details['class'] = 'cachestore_'.$details['plugin'];
             $name = $details['name'];
         }