Fatal error: Uncaught Error: Class "Drupal\Tests\BrowserTestBase" not found in /home/qcsvlel/www/core/tests/Drupal/FunctionalTests/Test/FunctionalTestDebugHtmlOutputHelperTest.php:16 Stack trace: #0 {main} thrown in /home/qcsvlel/www/core/tests/Drupal/FunctionalTests/Test/FunctionalTestDebugHtmlOutputHelperTest.php on line 16