How to use the gokart.gcs_config.GCSConfig function in gokart

def test_get_gcs_client_with_file_path(self):
        mock = MagicMock()
        file_path = 'test.json'
        os.environ['env_name'] = file_path
        with patch('luigi.contrib.gcs.GCSClient'):
            with patch('google.oauth2.service_account.Credentials.from_service_account_file', mock):
                with patch('os.path.isfile', return_value=True):
                    GCSConfig(gcs_credential_name='env_name').get_gcs_client()
                    self.assertEqual(file_path, mock.call_args[0][0])

def test_get_gcs_client_with_json(self):
        mock = MagicMock()
        json_str = '{"test": 1}'
        os.environ['env_name'] = json_str
        with patch('luigi.contrib.gcs.GCSClient'):
            with patch('google.oauth2.service_account.Credentials.from_service_account_info', mock):
                GCSConfig(gcs_credential_name='env_name').get_gcs_client()
                self.assertEqual(dict(test=1), mock.call_args[0][0])

def test_get_gcs_client_without_gcs_credential_name(self):
        mock = MagicMock()
        with patch('luigi.contrib.gcs.GCSClient', mock):
            GCSConfig().get_gcs_client()
            self.assertEqual(dict(oauth_credentials=None), mock.call_args[1])

def get_timestamp(path: str) -> datetime:
        if path.startswith('s3://'):
            return S3Config().get_s3_client().get_key(path).last_modified
        elif path.startswith('gs://'):
            # for gcs object
            # should PR to luigi
            bucket, obj = GCSConfig().get_gcs_client()._path_to_bucket_and_key(path)
            result = GCSConfig().get_gcs_client().client.objects().get(bucket=bucket, object=obj).execute()
            return result['updated']
        else:
            raise

def exists(path: str) -> bool:
        if path.startswith('s3://'):
            return S3Config().get_s3_client().exists(path)
        elif path.startswith('gs://'):
            return GCSConfig().get_gcs_client().exists(path)
        else:
            raise

def __init__(self, workspace_directory: str = '', task_filters: List[str] = [], tqdm_disable: bool = False):
        """must set $GCS_CREDENTIAL"""
        self.workspace_directory = workspace_directory
        self.task_filters = task_filters
        self.tqdm_disable = tqdm_disable
        self.gcs_client = GCSConfig().get_gcs_client()

def __init__(self, file_path: str, temporary_directory: str) -> None:
        self._file_path = file_path
        self._temporary_directory = temporary_directory
        self._client = GCSConfig().get_gcs_client()

def get_object_storage_target(path: str, format: Format) -> luigi.Target:
        if path.startswith('s3://'):
            return luigi.contrib.s3.S3Target(path, client=S3Config().get_s3_client(), format=format)
        elif path.startswith('gs://'):
            return luigi.contrib.gcs.GCSTarget(path, client=GCSConfig().get_gcs_client(), format=format)
        else:
            raise