Tests for Django Channels consumers: "No reply_channel sent to consumer" - django

Question

I am using Django Channels with the #channel_session_user decorator (for access to Django's session data).
#channel_session_user_from_http
def ws_connect(message):
# creates group names like "group-1"
group_kw = get_group_id_for_user(message.user)
Group(group_kw).add(message.reply_channel)
#channel_session_user
def ws_receive(message):
group_kw = get_group_id_for_user(message.user)
payload = json.loads(message.content['text'])
Channel(payload['action']).send(message.content)
#channel_session_user
def ws_disconnect(message):
group_kw = get_group_id_for_user(message.user)
Group(group_kw).discard(message.reply_channel)
That works fine, but there is a problem when testing.
The below test should place a message on the websocket.receive channel, then ws_receive should take the message and place it on the channel defined in the message's action value. Finally, I test if it was in fact placed on that channel.
def test_send_chat_message_is_used_by_consumer(self):
# Make sure a user is authenticated
self.assertTrue(auth.get_user(self.client).is_authenticated())
payload = {'action': 'chat.receive',
'msg': 'Test message.',
'receiver': self.user2.id}
message = {'text': json.dumps(payload)}
# Send a chat message
Channel('websocket.receive').send(message)
# Receive it and place it on the right channel
ws_receive(self.get_next_message('websocket.receive', require=True))
# Fetch it from the channel
result = self.get_next_message(payload['action'], require=True)
# That should be the message sent
self.assertEqual(result, message)
Instead, I get the following error, pointing to the line with the ws_receive() call.
ValueError: No reply_channel sent to consumer; #channel_session can only be used on messages containing it.
The error is raised here in the Channels source.
Printing the reply_channel returns None instead of containing the correct reply channel name.
tmp = self.get_next_message('websocket.receive', require=True)
print(tmp.reply_channel) # prints: None
I am overlooking something obvious?

Answer 1

I think you cannot just simply call the consumer because it has the decorator #channel_session_user. You should try using the Client channels.tests provides.
from channels.tests import ChannelTestCase, Client
Then use something like this inside the test function
client = Client()
client.send('websocket.receive', content=message)

Answer 2

This is because the name that you provide to the 'Channel' object represents the channel this message was received on. Check the init function of Channel.
Also note the function get_next_message in tests/base.py file. The channel parameter here refers to (reply) channel to which the message was sent to during the test.
To answer your question -
Look at the docstring of Message object in channels/message.py. It says,
The message content is a dict called .content, while reply_channel is an optional extra attribute representing a channel to use to reply to this message's end user, if that makes sense.
You need to set the "reply_channel" in the dict that you send.
message = {
'text': json.dumps(payload),
'reply_channel': 'websocket.receive'
}
Hope it helps