Why I'm getting this PHP error?
Fatal error: Class 'PHPUnit_Framework_TestCase' not found in ...
For those arriving here after updating phpunit to version 6 or greater released on 2017-02-03 (e.g. with composer), you may be getting this error because phpunit code is now namespaced (check changelog).
You will need to refactor things like \PHPUnit_Framework_TestCase
to \PHPUnit\Framework\TestCase