Fatal error: Uncaught Error: Class "Drupal\Tests\Core\Render\RendererTestBase" not found in /home/qcsvlel/www/core/tests/Drupal/Tests/Core/Render/PlaceholderGeneratorTest.php:14 Stack trace: #0 {main} thrown in /home/qcsvlel/www/core/tests/Drupal/Tests/Core/Render/PlaceholderGeneratorTest.php on line 14