title: How can solve this deprecationWarning?
body: <p>I want multi requests using aiohttp.
  I was wrapping aiohttp like this, and i was test like this</p>
  
  <p>my code</p>
  
  <pre class="lang-py prettyprint-override"><code>import asyncio
  from aiohttp import ClientSession as AioClientSession
  
  
  class ClientSession(AioClientSession):
      async def _get(self, session, url, params=None, **kwargs):
          async with session.get(url, params=params, **kwargs) as response:
              return await response.json()
  
      async def _post(self, session, url, data=None, **kwargs):
          async with session.post(url, data=data, **kwargs) as response:
              return await response.json()
  
      async def fetch_all(self, method, urls, loop, data=None, params=None, **kwargs):
          async with AioClientSession(loop=loop) as session:
              if method == "GET":
                  results = await asyncio.gather(*[self._get(session, url, params=params, **kwargs) for url in urls])
              elif method == "POST":
                  results = await asyncio.gather(*[self._post(session, url, data=data, **kwargs) for url in urls])
              else:
                  assert False
              return results
  
  
  def multi_requests_get(urls, params=None, **kwargs):
      session = ClientSession()
      loop = asyncio.get_event_loop()
      result = loop.run_until_complete(session.fetch_all("GET", urls, loop, params=params, **kwargs))
      session.close()
      return result
  
  
  def multi_requests_post(urls, data=None, **kwargs):
      session = ClientSession()
      loop = asyncio.get_event_loop()
      result = loop.run_until_complete(session.fetch_all("POST", urls, loop, data=data, **kwargs))
      session.close()
      return result
  </code></pre>
  
  <p>test code</p>
  
  <pre class="lang-py prettyprint-override"><code>urls = ["https://httpbin.org/get?{}={}".format(x, x) for x in range(10)]
  
  result = multi_requests_get(urls=urls)
  
  assert result
  assert result[0]["args"] == {"0": "0"}
  assert result[1]["args"] == {"1": "1"}
  </code></pre>
  
  <p>but this test return Warning like this:</p>
  
  <pre><code>The object should be created from async function
      loop=loop)
  </code></pre>
  
  <p>How can I avoid this warning?</p>
  
  <p>Here is the full traceback</p>
  
  <pre><code>============================================================================= warnings summary ==============================================================================
  base/tests/test_aiohttp.py::AioHttpTest::test_get
    /path/server/base/requests.py:122: DeprecationWarning: The object should be created from async function
      session = ClientSession()
  
  base/tests/test_aiohttp.py::AioHttpTest::test_get
  base/tests/test_aiohttp.py::AioHttpTest::test_post
    /env_path/lib/python3.6/site-packages/aiohttp/connector.py:730: DeprecationWarning: The object should be created from async function
      loop=loop)
  
  base/tests/test_aiohttp.py::AioHttpTest::test_get
  base/tests/test_aiohttp.py::AioHttpTest::test_post
    /env_path/lib/python3.6/site-packages/aiohttp/connector.py:735: DeprecationWarning: The object should be created from async function
      resolver = DefaultResolver(loop=self._loop)
  
  base/tests/test_aiohttp.py::AioHttpTest::test_get
  base/tests/test_aiohttp.py::AioHttpTest::test_post
    /env_path/lib/python3.6/site-packages/aiohttp/cookiejar.py:55: DeprecationWarning: The object should be created from async function
      super().__init__(loop=loop)
  
  base/tests/test_aiohttp.py::AioHttpTest::test_get
    /path/darae/server/base/requests.py:125: RuntimeWarning: coroutine 'ClientSession.close' was never awaited
      session.close()
  
  base/tests/test_aiohttp.py::AioHttpTest::test_post
    /path/server/base/requests.py:131: DeprecationWarning: The object should be created from async function
      session = ClientSession()
  
  base/tests/test_aiohttp.py::AioHttpTest::test_post
    /path/server/base/requests.py:134: RuntimeWarning: coroutine 'ClientSession.close' was never awaited
      session.close()
  
  -- Docs: https://docs.pytest.org/en/latest/warnings.html
  =================================================================== 2 passed, 10 warnings in 1.93 seconds ===================================================================
  </code></pre>