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Re: unit testing class hierarchies

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On 3 October 2012 02:20, Steven D'Aprano
<steve+comp.lang.python@pearwood.info> wrote:
>
> But surely, regardless of where that functionality is defined, you still
> need to test that both D1 and D2 exhibit the correct behaviour? Otherwise
> D2 (say) may break that functionality and your tests won't notice.
>
> Given a class hierarchy like this:
>
> class AbstractBaseClass:
>     spam = "spam"
>
> class D1(AbstractBaseClass): pass
> class D2(D1): pass
>
>
> I write tests like this:
>
> class TestD1CommonBehaviour(unittest.TestCase):
>     cls = D1
>     def testSpam(self):
>          self.assertTrue(self.cls.spam == "spam")
>     def testHam(self):
>          self.assertFalse(hasattr(self.cls, 'ham'))
>
> class TestD2CommonBehaviour(TestD1CommonBehaviour):
>     cls = D2

That's an excellent idea. I wanted a convenient way to run the same
tests on two classes in order to test both a pure python and a
cython-accelerator module implementation of the same class. I find it
difficult to work out how to do such simple things with unittest
because of its Java-like insistence on organising all tests into
classes. I can't immediately remember what solution I came up with but
yours is definitely better.


Oscar

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unit testing class hierarchies Ulrich Eckhardt <ulrich.eckhardt@dominolaser.com> - 2012-10-02 14:27 +0200
  Re: unit testing class hierarchies Demian Brecht <demianbrecht@gmail.com> - 2012-10-02 07:05 -0700
  Re: unit testing class hierarchies Thomas Bach <thbach@students.uni-mainz.de> - 2012-10-02 16:06 +0200
    Re: unit testing class hierarchies Ulrich Eckhardt <ulrich.eckhardt@dominolaser.com> - 2012-10-02 17:24 +0200
    Re: unit testing class hierarchies Ulrich Eckhardt <ulrich.eckhardt@dominolaser.com> - 2012-10-02 18:54 +0200
      Re: unit testing class hierarchies Peter Otten <__peter__@web.de> - 2012-10-02 19:38 +0200
      Re: unit testing class hierarchies Mark Lawrence <breamoreboy@yahoo.co.uk> - 2012-10-02 19:41 +0100
      Re: unit testing class hierarchies Ben Finney <ben+python@benfinney.id.au> - 2012-10-03 08:30 +1000
        Re: unit testing class hierarchies Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-10-03 01:20 +0000
          Re: unit testing class hierarchies Oscar Benjamin <oscar.j.benjamin@gmail.com> - 2012-10-03 10:33 +0100
          Re: unit testing class hierarchies Terry Reedy <tjreedy@udel.edu> - 2012-10-03 16:14 -0400
  Re: unit testing class hierarchies Peter Otten <__peter__@web.de> - 2012-10-02 16:32 +0200
  Re: unit testing class hierarchies Fayaz Yusuf Khan <fayaz@dexetra.com> - 2012-10-02 20:35 +0530
  Re: unit testing class hierarchies Peter Otten <__peter__@web.de> - 2012-10-02 19:40 +0200
    Re: unit testing class hierarchies Roy Smith <roy@panix.com> - 2012-10-02 19:46 -0400

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