def go():
            req = self.make_request('GET', '/')
            ws = WebSocketResponse()
            ws.start(req)

            @asyncio.coroutine
            def receive_msg():
                return websocket.Message(websocket.MSG_BINARY, b'data', b'')

            ws.receive_msg = receive_msg

            with self.assertRaises(TypeError):
                yield from ws.receive_str()