Fatal error: Uncaught Error: Class "Drupal\Tests\user\Functional\Rest\UserResourceTestBase" not found in /home/www/drupal8/test/core/modules/user/tests/src/Functional/Rest/UserJsonBasicAuthTest.php:10
Stack trace:
#0 {main}
thrown in /home/www/drupal8/test/core/modules/user/tests/src/Functional/Rest/UserJsonBasicAuthTest.php on line 10