Fatal error: Uncaught Error: Class "PHPUnit\Framework\TestCase" not found in /var/www/usonboard.com/vendor/guzzlehttp/psr7/tests/AppendStreamTest.php:12 Stack trace: #0 {main} thrown in /var/www/usonboard.com/vendor/guzzlehttp/psr7/tests/AppendStreamTest.php on line 12