Fatal error: Uncaught Error: Class "Drupal\Tests\field\Functional\String\StringFieldTest" not found in /home/www/drupal8/test/core/modules/text/tests/src/Functional/TextFieldTest.php:18 Stack trace: #0 {main} thrown in /home/www/drupal8/test/core/modules/text/tests/src/Functional/TextFieldTest.php on line 18