code: def test_trainer(
      self, monkeypatch: monkeypatch.MonkeyPatch, tmp_path: pathlib.Path
  ) -> None:
      # there is no direct way to set tensorboard path in Trainer API
      def mock_get_tensorboard_path(
          dummy: typing.Dict[str, typing.Any]
      ) -> pathlib.Path:
          return tmp_path.joinpath("tensorboard")
  
      monkeypatch.setattr(
          pytorch.PyTorchTrialContext,
          "get_tensorboard_path",
          mock_get_tensorboard_path,
      )
  
      # Train for 100 batches, checkpoint and validate every 50 batches
      max_batches = 100
      with pytorch.init(hparams=self.hparams) as train_context:
          trial = pytorch_onevar_model.OneVarTrial(train_context)
          trainer = pytorch.Trainer(trial, train_context)
          trainer.fit(
              max_length=pytorch.Batch(max_batches),
              checkpoint_period=pytorch.Batch(max_batches // 2),
              validation_period=pytorch.Batch(max_batches // 2),
          )
  
      # Verify training and validation metrics for batches trained
      metrics_callback = trial.metrics_callback
      batch_metrics = metrics_callback.batch_metrics
      assert (
          len(batch_metrics) == max_batches
      ), "batch metrics did not match expected length"
  
      validation_metrics = metrics_callback.validation_metrics
      assert (
          len(validation_metrics) == 2
      ), "validation metrics did not match expected length"
  
      # Verify checkpoint
      checkpoint_callback = trial.checkpoint_callback
      assert (
          len(checkpoint_callback.uuids) == 2
      ), "checkpoint callback did not return expected length of uuids"
  
imports: import contextlib
  import importlib
  import io
  import os
  import pathlib
  import sys
  import typing
  from unittest import mock
  import numpy
  import pytest
  import torch
  from _pytest import monkeypatch
  from torch.distributed import launcher
  import determined
  from determined import pytorch
  from tests.experiment import pytorch_utils, utils
  from tests.experiment.fixtures import pytorch_onevar_model
label_desc: Use image node_id 24 for calling the TestPyTorchTrial obj's underlying member method code with example usage: obj.test_trainer(monkeypatch, tmp_path) and returns: tmp_path