Route task to proper queue

[humitos]

In #4033, I introduce a bug when using Celery signatures.

From Celery's docs at http://docs.celeryproject.org/en/latest/reference/celery.html#celery.signature

the .s() shortcut does not allow you to specify execution options but there’s a chaning .set method that returns the signature

So, instead of dealing with multiple .set(), I'm just using the .signature() method of the task which is more explicit.

Ref: https://github.com/rtfd/readthedocs-ops/pull/392#issuecomment-414816823

[humitos]

I tested this locally by running an extra celery worker:

celery -A readthedocs worker -n build03 -Q build03 -l DEBUG -c 2

and setting build03 as the queue for the project to be built.

[ericholscher]

Looks good except for the failing tests.

Is there a way to test this, so it doesn't break in the future? It seems like we're just testing the mock call, but not that it's the proper call to celery. Hrm.

[humitos]

I'm not sure if there is a better way to test this. I think the problem with this was that I modified/wrote invalid tests for this. Now, I added a test that checks that the specific queue used in project.build_queue is the one passed to the task's signature.

Still, this is not perfect, but I suppose we are a little safer now with this test.