Fatal error: Uncaught Error: Class "PHPUnit\Framework\TestCase" not found in C:\xampp\htdocs\vendor\athlon1600\youtube-downloader\tests\YouTubeUrlTest.php:8 Stack trace: #0 {main} thrown in C:\xampp\htdocs\vendor\athlon1600\youtube-downloader\tests\YouTubeUrlTest.php on line 8