Fatal error: Uncaught Error: Class "PHPUnit\Framework\TestCase" not found in C:\xampp\htdocs\r10csm\vendor\guzzlehttp\psr7\tests\UtilsTest.php:13 Stack trace: #0 {main} thrown in C:\xampp\htdocs\r10csm\vendor\guzzlehttp\psr7\tests\UtilsTest.php on line 13