class_docstr: Inherit this class to test your DatasetBuilder class.
  
  You must set the following class attributes:
  
    * DATASET_CLASS: class object of DatasetBuilder you want to test.
    * SPLITS: dict mapping split name to expected number of examples.
  
  You may set the following class attributes:
  
    * VERSION: `str`. The version used to run the test. eg: '1.2.*'.
      Defaults to None (canonical version).
    * BUILDER_CONFIG_NAMES_TO_TEST: `list[str | tfds.core.BuilderConfig]`,
      the list of builder configs that should be tested. If None, all the
      BUILDER_CONFIGS from the class will be tested.
    * DL_EXTRACT_RESULT: `dict[str, str]`, the returned result of mocked
      `download_and_extract` method. The values should be the path of files
      present in the `fake_examples` directory, relative to that directory.
      If not specified, path to `fake_examples` will always be returned.
    * DL_EXTRACT_ONLY_RESULT: `dict[str, str]`, the returned result of mocked
      `extract` method. The values should be the path of files present in the
      `fake_examples` directory, relative to that directory. If not specified:
      will call DownloadManager `extract` method.
    * DL_DOWNLOAD_RESULT: `dict[str, str]`, the returned result of mocked
      `download_and_extract` method. The values should be the path of files
      present in the `fake_examples` directory, relative to that directory.
      If not specified: will use DL_EXTRACT_RESULT (this is due to backwards
      compatibility and will be removed in the future).
    * EXAMPLE_DIR: `str`, the base directory in in which fake examples are
      contained. Optional; defaults to `<dataset dir>/dummy_data/`.
    * OVERLAPPING_SPLITS: `list[str]`, splits containing examples from other
      splits (e.g. a "example" split containing pictures from other splits).
    * MOCK_OUT_FORBIDDEN_OS_FUNCTIONS: `bool`, defaults to True. Set to False to
      disable checks preventing usage of `os` or builtin functions instead of
      recommended `tf.io.gfile` API.
    * SKIP_CHECKSUMS: Checks that the urls called by `dl_manager.download`
      are registered.
    * SKIP_TF1_GRAPH_MODE: Runs in eager mode only.
  
  This test case will check for the following:
  
   - the dataset builder is correctly registered, i.e. `tfds.load(name)` works;
   - the dataset builder can read the fake examples stored in
       testing/test_data/fake_examples/{dataset_name};
   - the dataset builder can produce serialized data;
   - the dataset builder produces a valid Dataset object from serialized data
     - in eager mode;
     - in graph mode.
   - the produced Dataset examples have the expected dimensions and types;
   - the produced Dataset has and the expected number of examples;
   - a example is not part of two splits, or one of these splits is whitelisted
       in OVERLAPPING_SPLITS.
code: def _download_checksums(self, url):
      del url  # Unused
      self._stop_record_download = True
  
imports: import collections
  import contextlib
  import difflib
  import hashlib
  import itertools
  import numbers
  import os
  import textwrap
  from typing import Iterator, List, Mapping, Optional, Union
  from unittest import mock
  from absl import logging
  from absl.testing import parameterized
  from etils import epath
  import numpy
  from tensorflow_datasets.core import dataset_builder
  from tensorflow_datasets.core import dataset_info
  from tensorflow_datasets.core import dataset_metadata
  from tensorflow_datasets.core import dataset_utils
  from tensorflow_datasets.core import download
  from tensorflow_datasets.core import load
  from tensorflow_datasets.core import utils
  from tensorflow_datasets.core import visibility
  from tensorflow_datasets.core.download import checksums
  from tensorflow_datasets.core.utils.lazy_imports_utils import tensorflow
  from tensorflow_datasets.testing import feature_test_case
  from tensorflow_datasets.testing import test_utils
label_desc: Use image node_id 17 for calling the DatasetBuilderTestCase obj's underlying member method code with example usage: obj._download_checksums(url) without return types