Fatal error: Uncaught Error: Class 'PHPUnit\Framework\TestCase' not found in /var/www/html/cake3-migration/vendor/cakephp/plugin-installer/tests/php56/TestCase/Installer/PluginInstallerTest.php:11
Stack trace:
#0 {main}
  thrown in /var/www/html/cake3-migration/vendor/cakephp/plugin-installer/tests/php56/TestCase/Installer/PluginInstallerTest.php on line 11