code: def test_post_item():
      response = client.post("/items/", json={"name": "Foo"})
      assert response.status_code == 200, response.text
      assert response.json() == {"item": {"name": "Foo"}}
  
file_path: fastapi/tests/test_union_body.py
imports: from typing import Optional, Union
  from dirty_equals import IsDict
  from fastapi import FastAPI
  from fastapi.testclient import TestClient
  from pydantic import BaseModel
label_desc: Use image node_id 3 for calling a global function with example usage: test_post_item() without return types