Fatal error: Uncaught Error: Class "Drupal\Core\Database\Database" not found in /home/www/drupal8/test/core/modules/system/tests/fixtures/update/drupal-8.update-test-schema-enabled.php:10 Stack trace: #0 {main} thrown in /home/www/drupal8/test/core/modules/system/tests/fixtures/update/drupal-8.update-test-schema-enabled.php on line 10