Fatal error: Uncaught Error: Class "PHPUnit\Framework\TestCase" not found in C:\WebServer\htdocs\bookshelf\vendor\ssddanbrown\htmldiff\tests\WordSplitterTest.php:6 Stack trace: #0 {main} thrown in C:\WebServer\htdocs\bookshelf\vendor\ssddanbrown\htmldiff\tests\WordSplitterTest.php on line 6