Fatal error: Uncaught Error: Class 'PHPUnit\Framework\TestCase' not found in /var/www/html/composer/vendor/guzzlehttp/guzzle/tests/Handler/CurlFactoryTest.php:21 Stack trace: #0 {main} thrown in /var/www/html/composer/vendor/guzzlehttp/guzzle/tests/Handler/CurlFactoryTest.php on line 21