Fatal error: Uncaught Error: Class "Drupal\Tests\file\Kernel\FileManagedUnitTestBase" not found in /home/qcsvlel/www/core/modules/file/tests/src/Kernel/ManagedFileTest.php:18 Stack trace: #0 {main} thrown in /home/qcsvlel/www/core/modules/file/tests/src/Kernel/ManagedFileTest.php on line 18