code: def test_checkpoint_created(self):
      cli.train_cli(self.cfg)
      checkpoint_path = os.getenv(
          self.cfg["environment_variable_names"][
              "lightly_last_checkpoint_path"
          ]
      )
      assert checkpoint_path.endswith(".ckpt")
      assert os.path.isfile(checkpoint_path)
  
file_path: lightly/tests/cli/test_cli_train.py
imports: import os
  import re
  import sys
  import tempfile
  import torchvision
  from hydra.experimental import compose, initialize
  from lightly import cli
  from tests.api_workflow.mocked_api_workflow_client import MockedApiWorkflowClient, MockedApiWorkflowSetup
label_desc: Use image node_id 3 for calling the TestCLITrain obj's underlying member method code with example usage: obj.test_checkpoint_created() without return types