code: def on_after_run_once(self):
      print(self.root.work.local_build_config.dockerfile)
      # ugly hack due to replacing `pytorch_lightning string
      assert (
          "pytorchlightning/pytorch_" + "lightning"
          in self.root.work.local_build_config.dockerfile.data[0]
      )
      return super().on_after_run_once()
  
imports: import logging
  import os
  import sys
  from unittest.mock import Mock
  from lightning.app.testing import LightningTestApp, application_testing
  from lightning.app.utilities.packaging.build_config import BuildConfig
  from tests_app import _TESTS_ROOT
label_desc: Use image node_id 1 for calling the DockerfileLightningTestApp obj's underlying member method code with example usage: obj.on_after_run_once() and returns: super