Fatal error: Uncaught Error: Class "Drupal\Tests\BrowserTestBase" not found in /home/qcsvlel/www/core/modules/user/tests/src/Functional/UserLogoutTest.php:15 Stack trace: #0 {main} thrown in /home/qcsvlel/www/core/modules/user/tests/src/Functional/UserLogoutTest.php on line 15