code: def test_save_checkpoint_empty_state(tmp_path):
      """Test that one can save an empty state with the base implementation in Strategy."""
      strategy = (
          SingleDeviceStrategy()
      )  # surrogate class to test implementation in base class
      save_checkpoint_mock = Mock()
      strategy.checkpoint_io.save_checkpoint = save_checkpoint_mock
  
      state = {}
      strategy.save_checkpoint(tmp_path, state)
      save_checkpoint_mock.assert_called_with(
          checkpoint=state, path=tmp_path, storage_options=None
      )
  
imports: from unittest import mock
  from unittest.mock import Mock, PropertyMock
  import pytest
  import torch
  from lightning.fabric.plugins import DoublePrecision, HalfPrecision, Precision
  from lightning.fabric.strategies import SingleDeviceStrategy
  from lightning.fabric.utilities.imports import _TORCH_GREATER_EQUAL_2_0
  from lightning.fabric.utilities.types import _Stateful
  from tests_fabric.helpers.runif import RunIf
label_desc: Use image node_id 2 for calling a global function with example usage: test_save_checkpoint_empty_state(tmp_path) without return types