[Cython] cython tests and py3k hash randomization

Vitja Makarov vitja.makarov at gmail.com
Fri Feb 24 06:24:12 CET 2012

2012/2/24 mark florisson <markflorisson88 at gmail.com>:
> On 23 February 2012 20:52, Vitja Makarov <vitja.makarov at gmail.com> wrote:
>> Recent py3k version has new feature "hash randomization" it solves
>> some security issues.
>> But has some drawbacks, for instance, dict.items() order is now
>> unknown. So it breaks
>> randomly some doctests that rely on exact order of dict items.
>> vitja at mchome:~/python$ ./py3k/bin/python -c  "print({'a':1, 'b':2})"
>> {'b': 2, 'a': 1}
>> vitja at mchome:~/python$ ./py3k/bin/python -c  "print({'a':1, 'b':2})"
>> {'a': 1, 'b': 2}
>> As a workaround we can set PYTHONHASHSEED environment variable to zero
>> for all cyhon-*-tests targets
>> This also affects generated code it internally depends on order of
>> items returned by dict.items()
> Any code or test that relies on dictionary order is wrong, really. So
> I assume any pyregr issues will be fixed by the CPython test suite? If
> there are any such failing tests in Cython we should simply fix them.

Yes, you're right but I'm not sure how many tests may be broken. I
don't think we want to fix
them before release. Now I've added

# Disable python hash randomization

to cython-devel-tests and it worked.

It's not that easy to fix, here is simple doctest:

def test_foo():
    >>> test_foo()
    {'a': 1, 'b': 2}
    return {'a': 1, 'b': 2}

You can't use dicts in doctests anymore there are few options instead:
1. Compare sorted items(), e.g. sorted(test_foo().items())
2. Inplace compare test_foo() == {...}


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