def _acceptAddressTest(self, family, localhost):
        """
        Create a C{SOCK_STREAM} connection to localhost using a socket with an
        address family of C{family} and assert that the result of
        L{iocpsupport.get_accept_addrs} is consistent with the result of
        C{socket.getsockname} and C{socket.getpeername}.
        """
        msg("family = %r" % (family,))
        port = socket(family, SOCK_STREAM)
        self.addCleanup(port.close)
        port.bind(('', 0))
        port.listen(1)
        client = socket(family, SOCK_STREAM)
        self.addCleanup(client.close)
        client.setblocking(False)
        try:
            client.connect((localhost, port.getsockname()[1]))
        except error as e:
            self.assertIn(e.errno, (errno.EINPROGRESS, errno.EWOULDBLOCK))

        server = socket(family, SOCK_STREAM)
        self.addCleanup(server.close)
        buff = array('B', b'\0' * 256)
        self.assertEqual(
            0, _iocp.accept(port.fileno(), server.fileno(), buff, None))
        server.setsockopt(
            SOL_SOCKET, SO_UPDATE_ACCEPT_CONTEXT, pack('P', port.fileno()))
        self.assertEqual(
            (family, client.getpeername()[:2], client.getsockname()[:2]),
            _iocp.get_accept_addrs(server.fileno(), buff))

        Create a C{SOCK_STREAM} connection to localhost using a socket with an
        address family of C{family} and assert that the result of
        L{iocpsupport.get_accept_addrs} is consistent with the result of
        C{socket.getsockname} and C{socket.getpeername}.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/test/test_iocp.py