Fatal error: Uncaught Error: Class "PHPUnit\Framework\TestCase" not found in /home/www/drupal8/test/core/modules/simpletest/tests/src/Unit/SimpletestPhpunitRunCommandTest.php:21 Stack trace: #0 {main} thrown in /home/www/drupal8/test/core/modules/simpletest/tests/src/Unit/SimpletestPhpunitRunCommandTest.php on line 21