code: def test_list_artifacts_empty(mock_client):
      repo = GCSArtifactRepository(
          "gs://test_bucket/some/path", client=mock_client
      )
      mock_client.bucket.return_value.list_blobs.return_value = (
          mock.MagicMock()
      )
      assert repo.list_artifacts() == []
  
imports: import os
  import posixpath
  from unittest import mock
  import pytest
  import requests
  from google.auth.exceptions import DefaultCredentialsError
  from google.cloud.storage import client
  from mlflow.entities.multipart_upload import MultipartUploadPart
  from mlflow.store.artifact.artifact_repository_registry import get_artifact_repository
  from mlflow.store.artifact.gcs_artifact_repo import GCSArtifactRepository, GCSMPUArguments
  from tests.helper_functions import mock_method_chain
label_desc: Use image node_id 3 for calling a global function with example usage: test_list_artifacts_empty(mock_client) without return types