[TIP] Tox and UserWarnings

[Albert-Jan Roskam]

Hi,

I am using a custom warning and I wanted to test whether it works as expected.

I wanted to suppress all warnings (PYTHONWARNINGS = ignore), except my own custom
warnings (action="default"). When I run test below in Tox, it passes in Python 

2.7, 3.4 and pypy, but not Python 3.3. When I run the test directly (not with Tox)
it works with all versions. If I set PYTHONWARNINGS = default, all tests pass in Tox.


Not a huge deal, but I thought it would be nice to mention it here. I have no idea why this
happens, but it seems that there are subtle cross-version differences wrt the warnings module.


#!/usr/bin/env python# 

-*- coding: utf-8 -*-
# test_booh.py
import unittest
import warnings

class MyCustomWarning(UserWarning): pass

warnings.filterwarnings("default", category=MyCustomWarning)

def panic():
     warnings.warn("Booh", MyCustomWarning, stacklevel=2)

class test_MyCustomWarning(unittest.TestCase):

    def test_raises_SPSSIOWarning(self):
        with warnings.catch_warnings(record=True) as warn:
            panic()
            mywarnings = [item.message for item in warn]
            self.assertTrue("Booh" in str(mywarnings)) # [1]
# [1] Python 3.3.4, in Tox:
# if setenv = PYTHONWARNINGS = ignore:
# --> AssertionError: False is not true
# if setenv = PYTHONWARNINGS = default:
# OK

if __name__ == "__main__":
    unittest.main()
 
Regards,

Albert-Jan




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