Fatal error: Uncaught Error: Interface "Drupal\Core\DependencyInjection\ServiceProviderInterface" not found in /home/www/drupal8/test/core/tests/Drupal/KernelTests/TestServiceProvider.php:13 Stack trace: #0 {main} thrown in /home/www/drupal8/test/core/tests/Drupal/KernelTests/TestServiceProvider.php on line 13