def METHOD_NAME(self):
    """Test _append_label step.
    Expected behavior is that the pipeline appends the String label (i.e.
    '0-2M') of each user to a list of dicts containing BigQuery output.
    """
    with TestPipeline() as p:
        input_data = (
            p
            | 'CreateDurationData' >> beam.Create(
                PreprocessTest.DURATION_DATA))
        label_data = (
            input_data
            | 'AppendLabel' >> beam.Map(
                preprocess.append_label))
        assert_that(label_data, equal_to(
            PreprocessTest.LABEL_DATA))