code: def test_custom_response_schema():
      response = client.get("/openapi.json")
      assert response.status_code == 200, response.text
      assert (
          response.json()["components"]["schemas"]["Item"]
          == item_schema
      )
  
file_path: fastapi/tests/test_custom_schema_fields.py
imports: from fastapi import FastAPI
  from fastapi._compat import PYDANTIC_V2
  from fastapi.testclient import TestClient
  from pydantic import BaseModel
label_desc: Use image node_id 2 for calling a global function with example usage: test_custom_response_schema() without return types