docstr: Test evaluate entry point with a callback
docstr_tok: ["Test","evaluate","entry","point","with","a","callback"]
code: def test_evaluate_with_callback(self) -> None:
      """
      Test evaluate entry point with a callback
      """
      input_dim = 2
      dataset_len = 10
      batch_size = 2
      max_steps_per_epoch = 6
      expected_num_steps = dataset_len / batch_size
  
      my_unit = DummyEvalUnit(2)
      dataloader = generate_random_dataloader(
          dataset_len, input_dim, batch_size
      )
  
      callback_mock = MagicMock()
  
      evaluate(
          my_unit,
          dataloader,
          max_steps_per_epoch=max_steps_per_epoch,
          callbacks=[callback_mock],
      )
  
      self.assertEqual(callback_mock.on_eval_start.call_count, 1)
      self.assertEqual(callback_mock.on_eval_epoch_start.call_count, 1)
      self.assertEqual(
          callback_mock.on_eval_step_start.call_count,
          expected_num_steps,
      )
      self.assertEqual(
          callback_mock.on_eval_step_end.call_count, expected_num_steps
      )
      self.assertEqual(callback_mock.on_eval_epoch_end.call_count, 1)
      self.assertEqual(callback_mock.on_eval_end.call_count, 1)
  
imports: import unittest
  from typing import Any, Iterator, Mapping, Tuple
  from unittest.mock import MagicMock
  import torch
  from torch import nn
  from torchtnt.framework._test_utils import DummyEvalUnit, generate_random_dataloader
  from torchtnt.framework.callback import Callback
  from torchtnt.framework.evaluate import evaluate
  from torchtnt.framework.state import State
  from torchtnt.framework.unit import EvalUnit, TEvalUnit
  from torchtnt.utils.timer import Timer
label_desc: Use image node_id 5 for calling the EvaluateTest obj's underlying member method code with example usage: obj.test_evaluate_with_callback() without return types