django channels WebsocketCommunicator TimeoutError - django

Question

I am trying to run the following test:
tests.py
from rest_framework.test import APITestCase
from myapp.routing import application
from channels.testing import WebsocketCommunicator
from account.models import User
from rest_framework.authtoken.models import Token
class Tests(APITestCase):
def setUp(self):
self.user = User.objects.create(email='test#test.test',
password='a password')
self.token, created = Token.objects.get_or_create(user=self.user)
async def test_connect(self):
communicator = WebsocketCommunicator(application, f"/ws/user/{self.token}/")
connected, subprotocol = await communicator.connect()
self.assertTrue(connected)
await communicator.disconnect()
application is a boilerplate instance of channels.routing.ProtocolTypeRouter (like in here: https://channels.readthedocs.io/en/latest/topics/routing.html). Everything works fine in production. The test exits with the following error:
Traceback (most recent call last):
File "/home/projects/myapp/myapp-env/lib/python3.7/site-packages/asgiref/testing.py", line 74, in receive_output
return await self.output_queue.get()
File "/usr/lib/python3.7/asyncio/queues.py", line 159, in get
await getter
concurrent.futures._base.CancelledError
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "/home/projects/myapp/myapp-env/lib/python3.7/site-packages/asgiref/sync.py", line 223, in __call__
return call_result.result()
File "/usr/lib/python3.7/concurrent/futures/_base.py", line 428, in result
return self.__get_result()
File "/usr/lib/python3.7/concurrent/futures/_base.py", line 384, in __get_result
raise self._exception
File "/home/projects/myapp/myapp-env/lib/python3.7/site-packages/asgiref/sync.py", line 292, in main_wrap
result = await self.awaitable(*args, **kwargs)
File "/home/projects/myapp/myapp-api/app/tests.py", line 35, in test_connect
connected, subprotocol = await communicator.connect()
File "/home/projects/myapp/myapp-env/lib/python3.7/site-packages/channels/testing/websocket.py", line 36, in connect
response = await self.receive_output(timeout)
File "/home/projects/myapp/myapp-env/lib/python3.7/site-packages/asgiref/testing.py", line 85, in receive_output
raise e
File "/home/projects/myapp/myapp-env/lib/python3.7/site-packages/asgiref/testing.py", line 74, in receive_output
return await self.output_queue.get()
File "/home/projects/myapp/myapp-env/lib/python3.7/site-packages/asgiref/timeout.py", line 66, in __aexit__
self._do_exit(exc_type)
File "/home/projects/myapp/myapp-env/lib/python3.7/site-packages/asgiref/timeout.py", line 103, in _do_exit
raise asyncio.TimeoutError
concurrent.futures._base.TimeoutError
----------------------------------------------------------------------
Ran 1 test in 1.026s
I have tried python versions 3.7.5, 3.8.0 and 3.9.9 using channels 3.0.4 with django 3.2.10 and channels-redis 3.3.1 ('BACKEND': 'channels_redis.core.RedisChannelLayer' in settings.py). The error persists. What am I doing wrong?

Answer 1

I had the same problem. APITestCase or TestCase dont allow transactions, you have to use SimpleTestCase from django test, and set databases to all. Just with that difference i think it will work.
Note that the transactions will be saved between test, and not rolled back after the test.
from django.test import SimpleTestCase
from myapp.routing import application
from channels.testing import WebsocketCommunicator
from account.models import User
from rest_framework.authtoken.models import Token
class Tests(SimpleTestCase):
databases = '__all__'
def setUp(self):
self.user = User.objects.create(email='test#test.test', password='a password')
self.token, created = Token.objects.get_or_create(user=self.user)
async def test_connect(self):
communicator = WebsocketCommunicator(application, f"/ws/user/{self.token}/")
connected, subprotocol = await communicator.connect()
self.assertTrue(connected)
await communicator.disconnect()
here are the information of SimpleTestCase
https://docs.djangoproject.com/en/4.0/topics/testing/tools/

Answer 2

I faced a similar issue and the solution is usually to mimic your production router for the tests too, i.e whatever middleware or additional component used in production should also be added when imstantiating your Communicator. for example in my asgi.py I have:
application = ProtocolTypeRouter(
{
"http": get_asgi_application(),
"websocket": AllowedHostsOriginValidator(
jwt_auth_middleware_stack(URLRouter(chat.routing.websocket_urlpatterns)),
),
}
)
My communicator is instantiated as follows:
communicator = WebsocketCommunicator(jwt_auth_middleware_stack(URLRouter(websocket_urlpatterns)),
f"/ws/chat/{chat.id}/?token={token}")
And my url is:
websocket_urlpatterns = [
path("ws/chat/<str:chat_id>/", consumers.AsyncChatConsumer.as_asgi())
]