code: def test_nullbyte_exception_handling_when_preimporting_airflow(
      self, mock_context, tmpdir
  ):
      mock_context.return_value.Pipe.return_value = (
          MagicMock(),
          MagicMock(),
      )
      dag_filename = os.path.join(tmpdir, "test_dag.py")
      with open(dag_filename, "wb") as file:
          file.write(b"hello\x00world")
  
      processor = DagFileProcessorProcess(
          file_path=dag_filename,
          pickle_dags=False,
          dag_ids=[],
          dag_directory=[],
          callback_requests=[],
      )
      processor.start()
  
imports: from __future__ import annotations
  import datetime
  import os
  from unittest import mock
  from unittest.mock import MagicMock, patch
  from zipfile import ZipFile
  import pytest
  from airflow import PY311, settings
  from airflow.callbacks.callback_requests import TaskCallbackRequest
  from airflow.configuration import TEST_DAGS_FOLDER, conf
  from airflow.dag_processing.manager import DagFileProcessorAgent
  from airflow.dag_processing.processor import DagFileProcessor, DagFileProcessorProcess
  from airflow.models import DagBag, DagModel, SlaMiss, TaskInstance, errors
  from airflow.models.serialized_dag import SerializedDagModel
  from airflow.models.taskinstance import SimpleTaskInstance
  from airflow.operators.empty import EmptyOperator
  from airflow.utils import timezone
  from airflow.utils.session import create_session
  from airflow.utils.state import State
  from airflow.utils.types import DagRunType
  from tests.test_utils.config import conf_vars, env_vars
  from tests.test_utils.db import clear_db_dags, clear_db_import_errors, clear_db_jobs, clear_db_pools, clear_db_runs, clear_db_serialized_dags, clear_db_sla_miss
  from tests.test_utils.mock_executor import MockExecutor
label_desc: Use image node_id 35 for calling the TestDagFileProcessor obj's underlying member method code with example usage: obj.test_nullbyte_exception_handling_when_preimporting_airflow(mock_context, tmpdir) without return types