code: def test_proxy_metrics_fields_not_found(serve_start_shutdown):
      """Tests the proxy metrics' fields' behavior for not found."""
  
      # Should generate 404 responses
      broken_url = "http://127.0.0.1:8000/fake_route"
      requests.get(broken_url).text
      print("Sent requests to broken URL.")
  
      # Ping gRPC proxy for not existing application.
      channel = grpc.insecure_channel("localhost:9000")
      fake_app_name = "fake-app"
      ping_grpc_call_method(
          channel=channel, app_name=fake_app_name, test_not_found=True
      )
  
      num_requests = get_metric_dictionaries("serve_num_http_requests")
      assert len(num_requests) == 1
      assert num_requests[0]["route"] == "/fake_route"
      assert num_requests[0]["method"] == "GET"
      assert num_requests[0]["application"] == ""
      assert num_requests[0]["status_code"] == "404"
      print("serve_num_http_requests working as expected.")
  
      num_requests = get_metric_dictionaries("serve_num_grpc_requests")
      assert len(num_requests) == 1
      assert num_requests[0]["route"] == fake_app_name
      assert (
          num_requests[0]["method"]
          == "/ray.serve.UserDefinedService/__call__"
      )
      assert num_requests[0]["application"] == ""
      assert num_requests[0]["status_code"] == str(
          grpc.StatusCode.NOT_FOUND
      )
      print("serve_num_grpc_requests working as expected.")
  
      num_errors = get_metric_dictionaries(
          "serve_num_http_error_requests"
      )
      assert len(num_errors) == 1
      assert num_errors[0]["route"] == "/fake_route"
      assert num_errors[0]["error_code"] == "404"
      assert num_errors[0]["method"] == "GET"
      print("serve_num_http_error_requests working as expected.")
  
      num_errors = get_metric_dictionaries(
          "serve_num_grpc_error_requests"
      )
      assert len(num_errors) == 1
      assert num_errors[0]["route"] == fake_app_name
      assert num_errors[0]["error_code"] == str(
          grpc.StatusCode.NOT_FOUND
      )
      assert (
          num_errors[0]["method"]
          == "/ray.serve.UserDefinedService/__call__"
      )
      print("serve_num_grpc_error_requests working as expected.")
  
imports: import os
  import sys
  from typing import DefaultDict, Dict, List, Optional
  import grpc
  import pytest
  import requests
  from fastapi import FastAPI
  import ray
  import ray.util.state
  from ray import serve
  from ray._private.test_utils import SignalActor, wait_for_condition
  from ray.serve._private.constants import DEFAULT_LATENCY_BUCKET_MS
  from ray.serve._private.long_poll import LongPollHost, UpdatedObject
  from ray.serve._private.test_utils import ping_fruit_stand, ping_grpc_call_method, ping_grpc_list_applications
  from ray.serve._private.utils import block_until_http_ready
  from ray.serve.config import gRPCOptions
  from ray.serve.handle import DeploymentHandle
  from ray.serve.metrics import Counter, Gauge, Histogram
  from ray.serve.tests.test_config_files.grpc_deployment import g, g2
label_desc: Use image node_id 6 for calling a global function with example usage: test_proxy_metrics_fields_not_found(serve_start_shutdown) without return types