public function setDirectory($directory = __DIR__)
    {
        if (!is_dir($directory)) {
            $message = "Directory {$directory} doesn't exist.";
            throw new \RuntimeException($message);
        }
        $this->directory = $directory;
        $this->gitattributesFile = $directory
            . DIRECTORY_SEPARATOR
            . '.gitattributes';

        return $this;
    }