import json
import responses
import requests
import threading

try:
   import urlparse
except ModuleNotFoundError:
   import urllib.parse as urlparse


server_url = 'http://server'
headers_json = {'content-type': 'application/json'}

def init():

    def endpoint(request):
        id = urlparse.parse_qs(urlparse.urlparse(request.path_url).query)["id"][0]
        data = {"foo": int(id)}
        return 200, headers_json, json.dumps(data)

    responses.add_callback(
        responses.GET, server_url + '/',
        callback=endpoint,
    )

def responses_routine():
    resp = requests.get(
        server_url + '/?id=456',
        headers=headers_json,
    )

     # {"foo": "456"}
    print(resp.json()["foo"])


t = threading.Timer(2, responses_routine)

@responses.activate
def test():

    init()
    t.start()

test()

import time
time.sleep(5)