How to use the mackup.constants.ENGINE_DROPBOX function in mackup

def test_config_apps_to_ignore_and_sync(self):
        cfg = Config("mackup-apps_to_ignore_and_sync.cfg")

        assert isinstance(cfg.engine, str)
        assert cfg.engine == ENGINE_DROPBOX

        assert isinstance(cfg.path, str)
        assert cfg.path == u"/home/some_user/Dropbox"

        assert isinstance(cfg.directory, str)
        assert cfg.directory == u"Mackup"

        assert isinstance(cfg.fullpath, str)
        assert cfg.fullpath == u"/home/some_user/Dropbox/Mackup"

        assert cfg.apps_to_ignore == set(["subversion", "sequel-pro", "sabnzbd"])
        assert cfg.apps_to_sync == set(["sabnzbd", "sublime-text-3", "x11", "vim"])

def _parse_path(self):
        """
        Parse the storage path in the config.

        Returns:
            str
        """
        if self.engine == ENGINE_DROPBOX:
            path = get_dropbox_folder_location()
        elif self.engine == ENGINE_GDRIVE:
            path = get_google_drive_folder_location()
        elif self.engine == ENGINE_COPY:
            path = get_copy_folder_location()
        elif self.engine == ENGINE_ICLOUD:
            path = get_icloud_folder_location()
        elif self.engine == ENGINE_BOX:
            path = get_box_folder_location()
        elif self.engine == ENGINE_FS:
            if self._parser.has_option("storage", "path"):
                cfg_path = self._parser.get("storage", "path")
                path = os.path.join(os.environ["HOME"], cfg_path)
            else:
                raise ConfigError(
                    "The required 'path' can't be found while"

def _parse_engine(self):
        """
        Parse the storage engine in the config.

        Returns:
            str
        """
        if self._parser.has_option("storage", "engine"):
            engine = str(self._parser.get("storage", "engine"))
        else:
            engine = ENGINE_DROPBOX

        assert isinstance(engine, str)

        if engine not in [
            ENGINE_DROPBOX,
            ENGINE_GDRIVE,
            ENGINE_COPY,
            ENGINE_ICLOUD,
            ENGINE_BOX,
            ENGINE_FS,
        ]:
            raise ConfigError("Unknown storage engine: {}".format(engine))

        return str(engine)

def _parse_engine(self):
        """
        Parse the storage engine in the config.

        Returns:
            str
        """
        if self._parser.has_option("storage", "engine"):
            engine = str(self._parser.get("storage", "engine"))
        else:
            engine = ENGINE_DROPBOX

        assert isinstance(engine, str)

        if engine not in [
            ENGINE_DROPBOX,
            ENGINE_GDRIVE,
            ENGINE_COPY,
            ENGINE_ICLOUD,
            ENGINE_BOX,
            ENGINE_FS,
        ]:
            raise ConfigError("Unknown storage engine: {}".format(engine))

        return str(engine)