public static function loadFile($filename)
    {
        if (class_exists(\PHPUnit\Util\Fileloader::class)) {
            // PHPUnit 6.x
            \PHPUnit\Util\Fileloader::checkAndLoad($filename);
        } else {
            // PHPUnit 7.x+
            \PHPUnit\Util\FileLoader::checkAndLoad($filename);
        }
    }