I have a basic Consumer that receives messages from the websocket and then broadcasts those messages to a channel specified in the message.
consumers.py
class BasicConsumer(AsyncJsonWebsocketConsumer):
async def receive_json(self, content, **kwargs):
channel = content['channel']
await self.channel_layer.send(
channel,
{
'type': 'some-message-type',
'body': content,
},
)
I then want to test this with pytest and pytest-asyncio like so
@pytest.mark.asyncio
async def test_basic_consumer():
channel_layer = get_channel_layer()
# connect to consumer
communicator = WebsocketCommunicator(BasicConsumer, "/my-url/")
connected, subprotocol = await communicator.connect()
assert connected
# generate valid channel name
channel_name = await channel_layer.new_channel()
await communicator.send_json_to({
'channel': channel_name,
'data': 'some-data',
})
from_channel_layer = await communicator.receive_output(timeout=5)
assert from_channel_layer == {
'type': 'some-message-type',
'body': {
'channel': channel_name,
'data': 'some-data',
},
}
My understanding is that communicator.receive_output() will retrieve the event the consumer sent to the channel layer. However I get the following error:
___________________________ test_basic_consumer ___________________________
self = <channels.testing.websocket.WebsocketCommunicator object at 0x7f901b5a87b8>
timeout = 5
async def receive_output(self, timeout=1):
"""
Receives a single message from the application, with optional timeout.
"""
# Make sure there's not an exception to raise from the task
if self.future.done():
self.future.result()
# Wait and receive the message
try:
async with async_timeout(timeout):
> return await self.output_queue.get()
vp3test/lib/python3.7/site-packages/asgiref/testing.py:75:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
self = <Queue at 0x7f901b5a8898 maxsize=0 tasks=1>
async def get(self):
"""Remove and return an item from the queue.
If queue is empty, wait until an item is available.
"""
while self.empty():
getter = self._loop.create_future()
self._getters.append(getter)
try:
> await getter
E concurrent.futures._base.CancelledError
/usr/lib/python3.7/asyncio/queues.py:159: CancelledError
During handling of the above exception, another exception occurred:
@pytest.mark.asyncio
async def test_basic_consumer():
channel_layer = get_channel_layer()
# connect to consumer
communicator = WebsocketCommunicator(BasicConsumer, "/my-url/")
connected, subprotocol = await communicator.connect()
assert connected
# generate valid channel name
channel_name = await channel_layer.new_channel()
await communicator.send_json_to({
'channel': channel_name,
'data': 'some-data',
})
> from_channel_layer = await communicator.receive_output(timeout=5)
test_consumers.py:150:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
vp3test/lib/python3.7/site-packages/asgiref/testing.py:86: in receive_output
raise e
vp3test/lib/python3.7/site-packages/asgiref/testing.py:75: in receive_output
return await self.output_queue.get()
vp3test/lib/python3.7/site-packages/asgiref/timeout.py:68: in __aexit__
self._do_exit(exc_type)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
self = <asgiref.timeout.timeout object at 0x7f901b5a8ba8>
exc_type = <class 'concurrent.futures._base.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 concurrent.futures._base.TimeoutError
vp3test/lib/python3.7/site-packages/asgiref/timeout.py:105: TimeoutError
Is there some more setup/configuration I need to do in my test?
Or am I using receive_output() wrong?
I am using InMemoryChannelLayer for the tests and the latest released version of everything.
My problem was that I was calling
from_channel_layer = await communicator.receive_output(timeout=5)
This is waiting for a message the consumer is sending down the websocket.
Instead I can call
from_channel_layer = await channel_layer.receive(channel_name)
to get the message the consumer is sending over the channel layer.