python – How to disable ssl verification for aiohttp test server

I want to write tests for a web client. As it was recommended by the aiohttp library author, I set up a local test server. This setup (boiling down this example) works well with plain http/port 80.

import ssl
import socket as skt
import unittest as ut

import aiohttp as ah
import aiohttp.web as ahweb
import aiohttp.test_utils as ahtest


async def function_to_test(client_session):
    async with client_session.get(EXPECTED_SERVER_URL) as response:
        return await response.json()

class ResolverMock(ah.resolver.AbstractResolver):
    def __init__(self, server_port, host, request_port):
        self.__server_port = server_port
        self.__host = host.rstrip("").rpartition('://')(-1)
        self.__request_port = request_port

    async def resolve(self, host, request_port=0, family=skt.AF_INET):
        if host != self.__host or request_port != self.__request_port:
            raise OSError('No test server known for %s' % host)
        return (dict(hostname=host, host='', port=self.__server_port,
                     family=skt.AF_INET, proto=0, flags=skt.AI_NUMERICHOST))

    async def close(self) -> None:

class ServerMock(ahtest.RawTestServer):
    def __init__(self, **kwargs):
        super().__init__(self.__handle_request, **kwargs)

    async def __handle_request(self, _request):
        return ahweb.json_response({})

class Fetch(ut.IsolatedAsyncioTestCase):
    async def test_request_server(self):
        async with ServerMock(port=443) as server_mock:
            ssl_ctx = False
            resolver = ResolverMock(server_port=server_mock.port, host=EXPECTED_SERVER_URL, request_port=443)
            connector = ah.TCPConnector(resolver=resolver, ssl=ssl_ctx, use_dns_cache=False)
            async with ah.ClientSession(connector=connector, trust_env=True) as session:
                response = await function_to_test(session)

        self.assertEqual(response, {})

if __name__ == '__main__':

But it fails for https/port 443 with
aiohttp.client_exceptions.ClientConnectorSSLError: Cannot connect to host ssl:default ((SSL: WRONG_VERSION_NUMBER) wrong version number (_ssl.c:1108))

Using a non_validating ssl context did not change anything:

            ssl_ctx = ssl.create_default_context()
            ssl_ctx.check_hostname = False
            ssl_ctx.verify_mode = ssl.CERT_NONE

I have no idea how I could set up a compatible protocol or whatever (I am far away from being an ssl expert) on the test server. What do I miss? How can I make this work for https?