Control async timeout when unit testing and using interactive debugging

[johnthagen]

When developing unit tests I find it often very valuable to step through the unit test and the code it calls in a visual debugger.

I am writing async tests using WebsocketCommunicator against an AsyncJsonWebsocketConsumer. If I put a break point within the consumer, the execution will pause as expected, but whenever I start running it again, I get a TimeoutError:

python3.10/site-packages/channels/testing/websocket.py:93: in receive_json_from
    payload = await self.receive_from(timeout)
python3.10/site-packages/channels/testing/websocket.py:72: in receive_from
    response = await self.receive_output(timeout)
python3.10/site-packages/asgiref/testing.py:85: in receive_output
    raise e
python3.10/site-packages/asgiref/testing.py:73: in receive_output
    async with async_timeout(timeout):
python3.10/site-packages/asgiref/timeout.py:71: in __aexit__
    self._do_exit(exc_type)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

self = <asgiref.timeout.timeout object at 0x11e6184c0>
exc_type = <class 'asyncio.exceptions.CancelledError'>

    def _do_exit(self, exc_type: Type[BaseException]) -> None:
        if exc_type is asyncio.CancelledError and self._cancelled:
            self._cancel_handler = None
            self._task = None
>           raise asyncio.TimeoutError
E           asyncio.exceptions.TimeoutError

python3.10/site-packages/asgiref/timeout.py:108: TimeoutError

This makes it very tedious to debug and step through various parts of the code.

How do users handle debugging async tests? I've also seen other similar issues when stepping in @database_sync_to_async functions. It seems like having a global timeout configuration or for the timeout not to be applied when debugging would be nice?

Curious how other users have handled this.

[johnthagen]

A one off workaround for some use cases is to temporarily change the unit test line to something like:

response = await communicator.receive_json_from(timeout=100)

Though this doesn't scale super well and is prone to forgetting to removing the timeout when debugging is done.

connect and disconnect calls would also potentially need to be modified when breaking within those methods of the Consumer.