code: def testTaxiPipelineCheckDagConstruction(self):
      airflow_config = {
          "schedule_interval": None,
          "start_date": datetime.datetime(2019, 1, 1),
      }
  
      # Create directory structure and write expected user module file.
      os.makedirs(os.path.join(self._test_dir, "taxi"))
      module_file = os.path.join(self._test_dir, "taxi/taxi_utils.py")
      with open(module_file, "w") as f:
          f.write("# Placeholder user module file.")
  
      # Patch $HOME directory for pipeline DAG construction.
      original_home = os.environ["HOME"]
      os.environ["HOME"] = self._test_dir
      from tfx.examples.chicago_taxi_pipeline import (
          taxi_pipeline_simple,
      )  # pylint: disable=g-import-not-at-top
  
      os.environ["HOME"] = original_home
  
      logical_pipeline = taxi_pipeline_simple._create_pipeline(
          pipeline_name="Test",
          pipeline_root=self._test_dir,
          data_root=self._test_dir,
          module_file=module_file,
          serving_model_dir=self._test_dir,
          metadata_path=self._test_dir,
          beam_pipeline_args=[],
      )
      self.assertEqual(9, len(logical_pipeline.components))
      pipeline = AirflowDagRunner(
          AirflowPipelineConfig(airflow_config)
      ).run(logical_pipeline)
      self.assertIsInstance(pipeline, models.DAG)
  
file_path: tfx/tfx/examples/chicago_taxi_pipeline/taxi_pipeline_simple_test.py
imports: import datetime
  import os
  from airflow import models
  import tensorflow
  from tfx.orchestration.airflow.airflow_dag_runner import AirflowDagRunner
  from tfx.orchestration.airflow.airflow_dag_runner import AirflowPipelineConfig
  from tfx.utils import test_case_utils
label_desc: Use image node_id 2 for calling the TaxiPipelineSimpleTest obj's underlying member method code with example usage: obj.testTaxiPipelineCheckDagConstruction() without return types