Fatal error: Uncaught Error: Interface "Drupal\Core\Config\Entity\ConfigEntityInterface" not found in /home/www/drupal8/test/core/modules/config/tests/config_test/src/ConfigTestInterface.php:10 Stack trace: #0 {main} thrown in /home/www/drupal8/test/core/modules/config/tests/config_test/src/ConfigTestInterface.php on line 10