code: def test_publish_data_dir(mock_fs: testing.MockFs):
      del mock_fs
      builder = testing.DummyMnist(data_dir="/tmp")
      actual = build_lib._publish_data_dir(
          publish_dir=epath.Path("/a/b"), builder=builder
      )
      assert actual == epath.Path("/a/b/dummy_mnist/3.0.1")
      assert (
          build_lib._publish_data_dir(publish_dir=None, builder=builder)
          is None
      )
  
imports: import contextlib
  import os
  import pathlib
  from typing import Dict, Iterator, List, Optional
  from unittest import mock
  from absl.testing import parameterized
  from etils import epath
  import pytest
  import tensorflow_datasets
  from tensorflow_datasets import testing
  from tensorflow_datasets.core import download
  from tensorflow_datasets.core import utils
  from tensorflow_datasets.core.utils import file_utils
  from tensorflow_datasets.scripts.cli import build
  from tensorflow_datasets.scripts.cli import main
label_desc: Use image node_id 13 for calling a global function with example usage: test_publish_data_dir(mock_fs) without return types