Fatal error: Uncaught Error: Class "Drupal\Tests\rest\Functional\ResourceTestBase" not found in /home/www/drupal8/test/core/modules/rest/tests/src/Functional/FileUploadResourceTestBase.php:21 Stack trace: #0 {main} thrown in /home/www/drupal8/test/core/modules/rest/tests/src/Functional/FileUploadResourceTestBase.php on line 21