diff --git a/core/tests/Drupal/Tests/Core/Entity/EntityManagerTest.php b/core/tests/Drupal/Tests/Core/Entity/EntityManagerTest.php
index d8e991b..9a67a26 100644
--- a/core/tests/Drupal/Tests/Core/Entity/EntityManagerTest.php
+++ b/core/tests/Drupal/Tests/Core/Entity/EntityManagerTest.php
@@ -1242,8 +1242,7 @@ public function testOnFieldDefinitionCreateNewField() {
     $field_definition->getName()->willReturn('test_field');
     $field_definition->getType()->willReturn('test_type');
 
-    $storage = $this->getMock(DynamicallyFieldableEntityStorageInterface::class);
-    $class = get_class($storage);
+    $class = $this->getMockClass(DynamicallyFieldableEntityStorageInterface::class);
     $entity = $this->prophesize(EntityTypeInterface::class);
     $entity->getHandlerClass('storage')->willReturn($class);
     $this->setUpEntityManager(array('test_entity_type' => $entity));
@@ -1278,8 +1277,7 @@ public function testOnFieldDefinitionCreateExistingField() {
     $field_definition->getTargetBundle()->willReturn('test_bundle');
     $field_definition->getName()->willReturn('test_field');
 
-    $storage = $this->getMock(DynamicallyFieldableEntityStorageInterface::class);
-    $class = get_class($storage);
+    $class = $this->getMockClass(DynamicallyFieldableEntityStorageInterface::class);
     $entity = $this->prophesize(EntityTypeInterface::class);
     $entity->getHandlerClass('storage')->willReturn($class);
     $this->setUpEntityManager(array('test_entity_type' => $entity));
@@ -1318,9 +1316,7 @@ public function testOnFieldDefinitionUpdate() {
     $field_definition = $this->prophesize(FieldDefinitionInterface::class);
     $field_definition->getTargetEntityTypeId()->willReturn('test_entity_type');
 
-    $storage = $this->getMock(DynamicallyFieldableEntityStorageInterface::class);
-
-    $class = get_class($storage);
+    $class = $this->getMockClass(DynamicallyFieldableEntityStorageInterface::class);
     $entity = $this->prophesize(EntityTypeInterface::class);
     $entity->getHandlerClass('storage')->willReturn($class);
     $this->setUpEntityManager(array('test_entity_type' => $entity));
@@ -1344,8 +1340,7 @@ public function testOnFieldDefinitionDeleteMultipleBundles() {
     $field_definition->getTargetBundle()->willReturn('test_bundle');
     $field_definition->getName()->willReturn('test_field');
 
-    $storage = $this->getMock(DynamicallyFieldableEntityStorageInterface::class);
-    $class = get_class($storage);
+    $class = $this->getMockClass(DynamicallyFieldableEntityStorageInterface::class);
     $entity = $this->prophesize(EntityTypeInterface::class);
     $entity->getHandlerClass('storage')->willReturn($class);
     $this->setUpEntityManager(array('test_entity_type' => $entity));
@@ -1391,8 +1386,7 @@ public function testOnFieldDefinitionDeleteSingleBundles() {
     $field_definition->getTargetBundle()->willReturn('test_bundle');
     $field_definition->getName()->willReturn('test_field');
 
-    $storage = $this->getMock(DynamicallyFieldableEntityStorageInterface::class);
-    $class = get_class($storage);
+    $class = $this->getMockClass(DynamicallyFieldableEntityStorageInterface::class);
     $entity = $this->prophesize(EntityTypeInterface::class);
     $entity->getHandlerClass('storage')->willReturn($class);
     $this->setUpEntityManager(array('test_entity_type' => $entity));