Re: [Matplotlib-users] testing issue involving matplotlib

[Benjamin R. <ben...@ou...>]

Hmmm, it isn't the same, but I wonder if it is related to the oddities
around https://github.com/matplotlib/matplotlib/pull/2925 . What I mean is
that in that case, none of our unit tests caught the problem, even though
it should have. In your case, your unit tests is catching a similar
problem, but there is no obvious reason why there should be a problem.

Now, technically speaking, in your case, there is a bug in the unittest
package (values() is an iterator in py3k rather than a list), but I
wouldn't know why that dictionary would change in the first place.



On Mon, Apr 14, 2014 at 2:54 PM, John Evans <joh...@gm...>wrote:

> Helllo, I'm seeing a strange issue when running unittests on python3.3 and
> python3.4 that somehow involves matplotlib.  My code has a somewhat
> complicated setup, but I think I've boiled the issue down to the following
> reproduction steps
>
>
> import unittest
> import warnings
>
> import matplotlib.pyplot
>
> class TestMe(unittest.TestCase):
>     def test_warn(self):
>         with self.assertWarns(UserWarning):
>             warnings.warn("a warning", UserWarning)
>
> if __name__ == "__main__":
>     unittest.main()
>
>
> It looks like it should pass, but it errors as follows
>
> E
> ======================================================================
> ERROR: test_warn (__main__.TestMe)
> ----------------------------------------------------------------------
> Traceback (most recent call last):
>   File "/homes/5/jevans/Downloads/testit.py", line 8, in test_warn
>     with self.assertWarns(UserWarning):
>   File
> "/space/getafix/1/users/jevans/anaconda/envs/py3k/lib/python3.3/unittest/case.py",
> line 177, in __enter__
>     for v in sys.modules.values():
> RuntimeError: dictionary changed size during iteration
>
> ----------------------------------------------------------------------
> Ran 1 test in 0.002
>
>
> If the matplotlib import is changed to just
>
> import matlotlib
>
> or if the matplotlib import is commented out altogether, it then passes.
>  I'm seeing the behavior on Anaconda with python 3.3 and matplotlib 1.3.1
> on both mac and linux, but also with MacPorts with pythons 3.3 and 3.4,
> matplotlib 1.3.1.  All seems fine with a  Fedora 20 laptop with python 3.3
> and also matplotlib 1.3.1.
>
>
> --
> John Evans
>
>
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