utils.suppress_warning, TestCase.assertWarns

[Shai Berger]

Hi all,

While working on a ticket that had to do with cookies, I found myself writing
this code (essentially):

with warnings.catch_warnings(record=True) as warnings_log:
#
# Begin actual code I'm trying to test
#
CsrfViewMiddleware().process_view(req, token_view, (), {})
#
# End actual code I'm trying to test
#
if (len(warnings_log) > 1 or
not issubclass(warnings_log[0].category, UnicodeWarning)):
for warning in warnings_log:
warnings.warn(warning)

The code I'm trying to test is going to make a UnicodeWarning, because the
whole point of the test is to see how the code deals with broken user input.
Having to wrap it in 5 lines of unrelated code feels odd.

So I thought a context manager to suppress specific warnings in a block might
be generally useful, and for tests, it may be even useful to have an
assertWarns -- an analog of assertRaises.

Opinions?

Thanks,
Shai.

[Tim Graham]

I think django.test.ignore_warnings may meet your needs.

As for the latter idea, unless something is really eager to add a Python 2 compatible version (if possible) to Django's SimpleTestCase, we can wait until dropping Python 2 support and then use the TestCase.assertWarns() in Python 3.2+.

[Shai Berger]

On Monday 04 April 2016 18:37:39 Tim Graham wrote:
> I think django.test.ignore_warnings may meet your needs.
>

Yes, probably. I had misunderstood the warnings.catch_warnings() documentation
(and might have misunderstood the django.test.ignore_warnings documentation as
well, if there was such doumentation).

> As for the latter idea, unless something is really eager to add a Python 2
> compatible version (if possible) to Django's SimpleTestCase, we can wait
> until dropping Python 2 support and then use the TestCase.assertWarns() in
> Python 3.2+.
>

Agreed.

Thanks,
Shai.