Django的单元测试是否向异常发出警告？

Question

I am using Django's unit testing apparatus (manage.py test), which is throwing an error and halting when the code generates a warning. This same code when tested with the standard Python unittest module, generates warnings but continues code execution through them.

A little research shows that Python can be set to raise warnings to exceptions, which I suppose would cause the testing framework to think an error had occurred. Unfortunately, the Django documentation on testing is a little light on the definition of an "error", or how to modify the handling of warnings.

So: Is the Django unit testing framework setup to raise warnings to errors by default? Is there some facility in Django for changing this behavior? If not, does anyone have any suggestions for how I can Django to print out the errors but continue code execution? Or have I completely misdiagnosed the problem?

UPDATE: The test code is halting on warnings thrown by calls on MySQLdb. Those calls are made by a module which throws the same warnings when tested under the Python unittest framework, but does not halt. I'll think about an efficient way of trying to replicate the situation in code terse enough to post.

ANSWER:

A little more research reveals this behavior is related to Django's MySQL backend:

/usr/...django/.../mysql/base.py:

if settings.DEBUG:
    ...
    filterwarnings("error", category=Database.Warning)

When I change settings.py so DEBUG = False, the code throws the warning but does not halt.

I hadn't previously encountered this behavior in Django because my database calls are generated by backend of my own. Since I didn't call the Django backend, I didn't reset the handling of the warnings, and the code continued despite the warnings. The Django test framework surely calls the Django backend -- it does all sorts of things with the database -- and that call would reset the warning handling before my code is called.

Answer 1

Given the updated info, I'm inclined to say that this is the right thing for Django to be doing; MySQL's warnings can indicate any number of things up to and including loss of data (eg, MySQL will warn and silently truncate if you try to insert a value larger than a column can hold), and that's the sort of thing you'd want to find out about when testing. So probably your best bet is to look at the warnings it's generating and change your code so that it no longer causes those warnings to happen.