code: def test_state_dict(self):
      self.callback_1.state_dict = Mock(return_value="test_1")
      self.callback_2.state_dict = Mock(return_value="test_2")
  
      state = self.list.state_dict()
  
      self.assertEqual(self.callback_1.state_dict.call_count, 1)
      self.assertEqual(self.callback_2.state_dict.call_count, 1)
      self.assertEqual(state[CallbackList.CALLBACK_STATES][0], "test_1")
      self.assertEqual(state[CallbackList.CALLBACK_STATES][1], "test_2")
      self.assertEqual(
          state[CallbackList.CALLBACK_TYPES][0], Tqdm().__class__
      )
      self.assertEqual(
          state[CallbackList.CALLBACK_TYPES][1], TensorBoard().__class__
      )
  
file_path: torchbearer/tests/callbacks/test_callbacks.py
imports: import warnings
  from unittest import TestCase
  from mock import MagicMock, Mock
  import torchbearer
  from torchbearer.callbacks import CallbackList, Tqdm, TensorBoard
label_desc: Use image node_id 2 for calling the TestCallbackList obj's underlying member method code with example usage: obj.test_state_dict() without return types