Fatal error: Uncaught Error: Class "Drupal\Tests\BrowserTestBase" not found in /home/qcsvlel/www/core/modules/package_manager/tests/src/Functional/PackageManagerTestBase.php:12 Stack trace: #0 {main} thrown in /home/qcsvlel/www/core/modules/package_manager/tests/src/Functional/PackageManagerTestBase.php on line 12