Fatal error: Uncaught Error: Class 'Drupal\Tests\BrowserTestBase' not found in /var/www/html/tmp/contrib/entity/tests/src/Functional/EntityDuplicateTest.php:16 Stack trace: #0 {main} thrown in /var/www/html/tmp/contrib/entity/tests/src/Functional/EntityDuplicateTest.php on line 16