old_contents: import functools
  from tornado import gen
  from tornado.httpclient import AsyncHTTPClient
  
  
  @gen.coroutine
  def fetch_coroutine(url):
      http_client = AsyncHTTPClient()
      response = yield http_client.fetch(url)
      raise gen.Return(response.code)
  
  
  def test_explicit_start_and_stop(io_loop):
      f = fetch_coroutine('http://google.com')
      f.add_done_callback(lambda future: io_loop.stop())
      io_loop.start()
      assert f.result() == 200
  
  
  def test_run_sync(io_loop):
      fetch = functools.partial(fetch_coroutine, 'http://google.com')
      response = io_loop.run_sync(fetch)
      assert response == 200
  
new_contents: import functools
  from tornado import gen
  
  
  @gen.coroutine
  def dummy_coroutine(io_loop):
      yield gen.Task(io_loop.add_callback)
      raise gen.Return(True)
  
  
  def test_explicit_start_and_stop(io_loop):
      future = dummy_coroutine(io_loop)
      future.add_done_callback(lambda *args: io_loop.stop())
      io_loop.start()
      assert future.result()
  
  
  def test_run_sync(io_loop):
      dummy = functools.partial(dummy_coroutine, io_loop)
      finished = io_loop.run_sync(dummy)
      assert finished
  
subject: remove an http call from tests ;)