code: def test_write_then_read(self):
      values = ["abcd", 91, {"x": "y"}]
      temp_dir = tempfile.mkdtemp()
      materializer = io_util.Materializer(temp_dir)
      with beam.Pipeline() as p:
          _ = p | beam.Create(values) | materializer.writer()
      got_values = []
      for val in materializer.reader():
          got_values.append(val)
      self.assertCountEqual(values, got_values)
  
file_path: data-validation/tensorflow_data_validation/utils/io_util_test.py
imports: import tempfile
  from absl.testing import absltest
  import apache_beam
  from tensorflow_data_validation.utils import io_util
label_desc: Use image node_id 1 for calling the MaterializerTest obj's underlying member method code with example usage: obj.test_write_then_read() without return types