async def METHOD_NAME(self):
    with self._patch_app_session():
        await self.server.start()
        await self.ws_connect()
        # Get our BrowserWebSocketHandler
        session_info = self.server._runtime._session_mgr.list_active_sessions()[0]
        websocket_handler: BrowserWebSocketHandler = session_info.client
        websocket_handler.on_message(
            BackMsg(debug_disconnect_websocket=True).SerializeToString()
        )
        self.assertIsNotNone(websocket_handler.ws_connection)