Fatal error: Uncaught Error: Interface "Drupal\Core\Field\FieldDefinitionInterface" not found in /home/www/drupal8/test/core/tests/Drupal/Tests/Core/Field/TestBaseFieldDefinitionInterface.php:11 Stack trace: #0 {main} thrown in /home/www/drupal8/test/core/tests/Drupal/Tests/Core/Field/TestBaseFieldDefinitionInterface.php on line 11