Thread urlconf isn't reset after response complete

[tpict]

When setting the urlconf on a request (e.g. in middleware for handling multiple domains pointing to the same Django app), it's not reset until the start of the next request. Since urlconf is threadlocal, this causes problems when running a suite of tests, even if the tests pass when ran individually. For example:

• Django test client makes a request that triggers a middleware to change the urlconf
• reverse is called with no urlconf kwarg, expecting to be given the urlconf specified by ROOT_URLCONF
• test throws NoReverseMatch

I took this problem to the IRC and found that another person recently messaged about the same thing: ​https://botbot.me/freenode/django/2018-08-07/?msg=103000008&page=3

[Carlton Gibson]

Any chance you could put this into a test case?

[Tim Graham]

There are a number of places in Django's test suite that set request.urlconf so I think a test is indeed needed to demonstrate the issue.

[tpict]

Replying to Tim Graham:
Sorry about the delay. I've just written a test case: ​https://github.com/tpict/django-29673-test-case

[Carlton Gibson]

Hi Tom.

Thanks for the example project. It's a curious one:

(tmp-d8650c87792fd55) ~/Downloads/django-29673-test-case-master $ ./manage.py test
..E.
======================================================================
ERROR: test_primary (django29673.secondary.tests.SecondaryTestCase)
Do stuff with the primary site.
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/Users/carlton/Downloads/django-29673-test-case-master/django29673/secondary/tests.py", line 12, in test_primary
    response = self.client.get(reverse("primary-site"))
  File "/Users/carlton/ve/tmp-d8650c87792fd55/lib/python3.6/site-packages/django/urls/base.py", line 90, in reverse
    return iri_to_uri(resolver._reverse_with_prefix(view, prefix, *args, **kwargs))
  File "/Users/carlton/ve/tmp-d8650c87792fd55/lib/python3.6/site-packages/django/urls/resolvers.py", line 622, in _reverse_with_prefix
    raise NoReverseMatch(msg)
django.urls.exceptions.NoReverseMatch: Reverse for 'primary-site' not found. 'primary-site' is not a valid view function or pattern name.

----------------------------------------------------------------------
Ran 4 tests in 0.017s

FAILED (errors=1)

(tmp-d8650c87792fd55) ~/Downloads/django-29673-test-case-master $ ./manage.py test django29673.secondary.tests.SecondaryTestCase
..
----------------------------------------------------------------------
Ran 2 tests in 0.009s

OK

The workaround you demonstrate in the ​the middleware.py file is interesting:

        # To make tests pass, comment the return statement and uncomment this
        # block:
        try:
            return self.get_response(request)
        finally:
            if getattr(request, "urlconf", None) is not None:
                set_urlconf(None)

If you'd like to push this forward, that would be great. Next step I guess I would be to bring the test case into the Django test suite in a PR.

[Tim Graham <timograham@…>]

In 18098d26:

Fixed #29673 -- Reset the URLconf at the end of each request.

Co-authored-by: Ross Thorne <rmwthorne@…>