code: def test_deepspeed_precision_optimizer_step():
      precision = DeepSpeedPrecision(precision="32-true")
      optimizer = model = Mock()
      precision.optimizer_step(optimizer, lr_kwargs={})
      model.step.assert_called_once_with(lr_kwargs={})
  
file_path: pytorch-lightning/tests/tests_fabric/plugins/precision/test_deepspeed.py
imports: from unittest import mock
  from unittest.mock import Mock
  import pytest
  import torch
  from lightning.fabric.plugins.precision.deepspeed import DeepSpeedPrecision
  from lightning.fabric.utilities.types import Steppable
  from tests_fabric.helpers.runif import RunIf
label_desc: Use image node_id 4 for calling a global function with example usage: test_deepspeed_precision_optimizer_step() without return types