docstr: Tests that the generator handles batches that contain no valid values.
docstr_tok: ["Tests","that","the","generator","handles","batches","that","contain","no","valid","values","."]
code: def test_time_stats_generator_no_valid_formats(self):
      """Tests that the generator handles batches that contain no valid values."""
      # None of these values is a valid format.
      input_batches = [
          pa.array([["", "2018-Nov-30", "20183011"]]),
          pa.array([["all/invalid", "2018-11-30invalid"]]),
          pa.array([["invalid2018-11-30", "invalid\n2018-11-30"]]),
      ]
      generator = time_stats_generator.TimeStatsGenerator(
          match_ratio=0.1, values_threshold=1
      )
      self.assertCombinerOutputEqual(
          input_batches,
          generator,
          statistics_pb2.FeatureNameStatistics(),
      )
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  from unittest import mock
  from absl.testing import absltest
  from absl.testing import parameterized
  import pyarrow
  from tensorflow_data_validation import types
  from tensorflow_data_validation.statistics.generators import time_stats_generator
  from tensorflow_data_validation.utils import test_util
  from tensorflow_metadata.proto.v0 import schema_pb2
  from tensorflow_metadata.proto.v0 import statistics_pb2
label_desc: Use image node_id 10 for calling the TimeStatsGeneratorTest obj's underlying member method code with example usage: obj.test_time_stats_generator_no_valid_formats() without return types