code: def test_smoke(self, prepare: "PrepareFixture"):
      caf_result = mock_create_artifact_files_result(["foo"])
      api = Mock(create_artifact_files=Mock(return_value=caf_result))
  
      step_prepare = StepPrepare(
          api=api,
          batch_time=1e-12,
          inter_event_time=1e-12,
          max_batch_size=1,
      )
      step_prepare.start()
  
      res = prepare(step_prepare, simple_file_spec(name="foo")).result()
      step_prepare.finish()
  
      upload_id = (
          caf_result["foo"]["uploadMultipartUrls"]["uploadID"]
          if caf_result["foo"]["uploadMultipartUrls"]
          else None
      )
  
      assert res == ResponsePrepare(
          birth_artifact_id=caf_result["foo"]["artifact"]["id"],
          upload_url=caf_result["foo"]["uploadUrl"],
          upload_headers=caf_result["foo"]["uploadHeaders"],
          upload_id=upload_id,
          storage_path=caf_result["foo"]["storagePath"],
          multipart_upload_urls=caf_result["foo"][
              "uploadMultipartUrls"
          ],
      )
  
imports: import asyncio
  import concurrent.futures
  import dataclasses
  import queue
  import threading
  from typing import TYPE_CHECKING, Iterable, Mapping, Tuple
  from unittest.mock import Mock, call
  import pytest
  from wandb.filesync.step_prepare import Request, RequestFinish, RequestPrepare, ResponsePrepare, StepPrepare, gather_batch
label_desc: Use image node_id 4 for calling the TestStepPrepare obj's underlying member method code with example usage: obj.test_smoke(prepare) without return types