Tester\Runner\CommandLine::checkArg PHP Method

    public function checkArg(array $opt, &$arg)
    {
        if (!empty($opt[self::REALPATH])) {
            $path = realpath($arg);
            if ($path === FALSE) {
                throw new \Exception("File path '{$arg}' not found.");
            }
            $arg = $path;
        }
    }