Fatal error: Uncaught Error: Class "PHPUnit\Framework\TestCase" not found in C:\Users\Administrator\Desktop\xamp\htdocs\sdk\guzzlehttp\psr7\tests\ResponseTest.php:16 Stack trace: #0 {main} thrown in C:\Users\Administrator\Desktop\xamp\htdocs\sdk\guzzlehttp\psr7\tests\ResponseTest.php on line 16