[Python-Dev] test_sys failures

Nick Coghlan ncoghlan at gmail.com
Fri Dec 21 09:05:44 CET 2007

Guido van Rossum wrote:
> When I build from scratch and run most tests (regrtest.py -uall) I get
> some strange failures with test_sys.py:
> test test_sys failed -- Traceback (most recent call last):
>   File "/usr/local/google/home/guido/python/py3kd/Lib/test/test_sys.py",
> line 302, in test_43581
>     self.assertEqual(sys.__stdout__.encoding, sys.__stderr__.encoding)
> AssertionError: 'ascii' != 'ISO-8859-1'
> The same test doesn't fail when run in isolation.
> Interestingly, I saw this with 2.5 as well as 3.0, but not with 2.6!
> Any ideas?

It looks like the chunk of code in TextIOWrapper might be getting 
different answers when trying to work out the encoding for stdin and 
stderr (not that I can see how that would happen...). Or maybe there is 
some way that test_sys could be seeing the temporary '__stderr__' entry 
that is put in place until the io module is available?

What do you get for stdin/stdout/stderr.encoding at the interactive 
prompt? On Ubuntu, I get UTF-8 for all of them in both 3.0a2 and 2.5.1, 
but I'm not seeing the problem, either.

Other values of possible interest:

Another possibility would be to throw some debugging code into io.py to 
print out the encoding name to stderr when file is 1 or 2.


Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia

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