code: def test_routes_healthz(serve_instance):
      resp = requests.get("http://localhost:8000/-/healthz")
      assert resp.status_code == 200
      assert resp.content == b"success"
  
file_path: ray/python/ray/serve/tests/test_http_routes.py
imports: import time
  import pytest
  import requests
  from fastapi import FastAPI, Request
  from starlette.responses import RedirectResponse
  import ray
  from ray import serve
  from ray.serve._private.constants import SERVE_DEFAULT_APP_NAME
label_desc: Use image node_id 2 for calling a global function with example usage: test_routes_healthz(serve_instance) without return types