Fatal error: Uncaught Error: Class "PHPUnit\Framework\TestCase" not found in C:\xampp\htdocs\r10ca\vendor\guzzlehttp\psr7\tests\NoSeekStreamTest.php:15 Stack trace: #0 {main} thrown in C:\xampp\htdocs\r10ca\vendor\guzzlehttp\psr7\tests\NoSeekStreamTest.php on line 15