Fatal error: Uncaught Error: Class 'PHPUnit\Framework\TestCase' not found in /home/opcon/src/composer/vendor/sendgrid/php-http-client/test/unit/ClientTest.php:9 Stack trace: #0 {main} thrown in /home/opcon/src/composer/vendor/sendgrid/php-http-client/test/unit/ClientTest.php on line 9