code: def test_preprocessing_fn(self):
      tfxio = dataset_tfxio_example._make_tfxio()
      self.assertAnalyzeAndTransformResults(
          tfxio.BeamSource(),
          tfxio.TensorAdapterConfig(),
          dataset_tfxio_example._preprocessing_fn,
          _EXPECTED_TRANSFORMED_OUTPUT,
      )
  
file_path: transform/examples/dataset_tfxio_example_test.py
imports: import tensorflow
  import dataset_tfxio_example
  from tensorflow_transform.beam import tft_unit
label_desc: Use image node_id 1 for calling the SimpleProcessingTest obj's underlying member method code with example usage: obj.test_preprocessing_fn() without return types