Fatal error: Uncaught Error: Class "Drupal\FunctionalTests\Installer\InstallerTestBase" not found in /home/www/drupal8/test/core/tests/Drupal/FunctionalTests/Installer/InstallerEmptySettingsTest.php:10
Stack trace:
#0 {main}
thrown in /home/www/drupal8/test/core/tests/Drupal/FunctionalTests/Installer/InstallerEmptySettingsTest.php on line 10