code: def test_mock_data_use_code():
      """Test `MockPolicy.USE_CODE` specific behavior."""
      with tfds.testing.mock_data(
          policy=tfds.testing.MockPolicy.USE_CODE
      ):
          builder = tfds.builder("mnist")
          # Dynamic metadata should be unknown.
          assert not list(builder.info.splits.keys())
  
          # As splits are unknown, any split can be loaded.
          ds = tfds.load("mnist", split="non_existent")
          assert set(ds.element_spec.keys()) == {"image", "label"}
  
          ds = tfds.data_source("mnist", split="non_existent")
          assert len(ds) == 1
          assert set(ds[0].keys()) == {"image", "label"}
  
imports: import functools
  import pickle
  import numpy
  import pytest
  import tensorflow
  import tensorflow_datasets
label_desc: Use image node_id 12 for calling a global function with example usage: test_mock_data_use_code() without return types