Deprecate SimpleTestCase.urls in favor of override_settings

[Tim Graham]

As summarized by Aymeric in #21518:

Clearly we'd better provide just "one way to [override ROOT_URLCONF" in the long term. We could consider the "urls" attribute as an old and specific way to override a particular setting. That would give us a reason deprecate it in favor of the standard settings override mechanisms, @override_settings(...) and with self.settings(...):.

[ANUBHAV JOSHI]

Which one way we should be going towards?

[Tim Graham]

We should see if it's feasible to replace SimpleTestCase.urls = 'foo' (and deprecate this syntax) with override_settings(ROOT_URLCONF='foo').

[ANUBHAV JOSHI]

Well I have tried replacing it at some places.
Is something like this: ​https://github.com/coder9042/django/compare/ticket_21977?expand=1 required?
Also do we need to remove the SimplaeTestCase.urls feature completely or just change usage??

[Tim Graham]

SimpleTestCase.urls will need to raise a warning as described in ​Deprecating a feature. You'll need to wait until we cut the 1.7 branch as the deprecation will need to start in 1.8.

[ANUBHAV JOSHI]

Ok I will work on the patch after 1.7 branch is cut out and new master is there.

[ANUBHAV JOSHI]

I have some doubts regarding this.

• Should the function which sets .urls should be changed or we are just changing its usage everywhere in the tests.

• Do I need to write a test for this?

[Tim Graham]

Yes, the function which sets urls should warn with a RemovedInDjango20Warning (two releases from now) so that users who are using this feature are warned to update their code. The deprecation message should say something like "SimpleTestCase.urls is deprecated, use @override_settings(ROOT_URLCONF=...) instead.".

A test to verify that the warning is raised under the appropriate circumstances wouldn't hurt.

[loic84]

I did a quick run with -Wall and found a couple of SimpleTestCase.urls that needed updating. Running the test suite with --selenium found a couple more, so there may be more skipped tests that need updating. I guess the logs of the CI will have to be monitored on the various setups.

The stacklevel for this warning isn't helpful at all, I've tried levels up to 6 with no luck, so the faulty TestCase really need to be specified in the warning message. For some reason -Werror doesn't do anything here, so the warning message is really the only indication one has to find the guilty TestCase.

Testing the deprecation is not that easy, I came up with:

class DeprecatingSimpleTestCaseUrls(unittest.TestCase):
    def test_deprecation(self):
        class TempTestCase(SimpleTestCase):
            urls = 'tests.urls'

            def test(self):
                pass

        with warnings.catch_warnings(record=True) as recorded:
            suite = unittest.TestLoader().loadTestsFromTestCase(TempTestCase)
            with open(os.devnull, 'w') as devnull:
                unittest.TextTestRunner(stream=devnull, verbosity=2).run(suite)

        # FIXME: Check that the correct warning is raised.
        self.assertTrue(recorded)

[ANUBHAV JOSHI]

PR: ​https://github.com/django/django/pull/2517

Thanks Loic for help in testing and reviewing.

[Tim Graham <timograham@…>]

In cd914e31c9a889f18c50c15b4f6ee4959624001f:

Fixed #21977 -- Deprecated SimpleTestCase.urls

[Tim Graham <timograham@…>]

In 1392aff:

Refs #21977 -- Removed SimpleTestCase.urls per deprecation timeline.

[Mihail Milushev]

​https://github.com/django/django/blob/master/django/core/handlers/base.py#L122

Performing any request while @override.settings(ROOT_URLCONF) is in effect stores that override in the ​django.urls.base._urlconfs thread local and nothing takes care to clean it up afterwards. This leads to leaking — once ROOT_URLCONF is overridden, it remains in effect even after the override goes out of scope and applies to all subsequent tests that try to resolve URLs before they perform a request (which is what would usually happen).

[Tim Graham]

Please open a new ticket with a failing test for Django's test suite or steps to reproduce, thanks.