private function setConfigDirectory(string $dirName): void
    {
        $dirName = realpath($this->getDirectory(Config::DIR_ROOT) . $dirName);

        if (is_dir($dirName)) {
            $this->configDirectory = $dirName;
        } else {
            if ($dirName !== false) {
                throw new \InvalidArgumentException(sprintf('Directory "%s" does not exists', $dirName));
            } else {
                throw new \InvalidArgumentException(sprintf('Config directory does not exists', $dirName));
            }
        }
    }