[TIP] Unit testing functions which call super

[Harry Percival]

If you know what the parent class is in advance, could you use mock.patch
to stub out the parent method?


On 13 August 2014 19:00, Marcin Tustin <Marcin.Tustin at dealertrack.com>
wrote:

>  Hi All,
>
>
>
> I’ve come across a method which I needed to add a unit test for, which
> calls super, e.g.
>
>
>
> def foofunc(self):
>
>     x= do_some_stuff()
>
>     if x:
>
>         return x
>
>     return super(WhatevClass, self).foofunc()
>
>
>
> Now, I don’t want to integration test the whole stack of super foofunc
> methods, just unit test that one, down to the super call.
>
>
>
> I’ve accomplished this with, in my test (excuse the 8 leading spaces):
>
>
>
> def setUp(self):
>
>         self.method_archive = {}
>
>         for klass in WhatevClass.__mro__[1:]:
>
>             # we use the class as its own sentinel
>
>             meth_or_klass = klass.__dict__.get('foofunc', klass)
>
>             if meth_or_klass != klass:
>
>                 self.method_archive[klass] = meth_or_klass
>
>                 del klass.foofunc
>
>         # now patch an arbitrary member of the mro to supply a dummy
> foofunc
>
>         self.sentinel_klass = next(iter(self.method_archive))
>
>         self.mock_sentinel = mock.MagicMock()
>
>         self.sentinel_klass.foofunc = self.mock_sentinel
>
>
>
>
>
> And corresponding unpatching in tearDown.
>
>
>
> Is there any other approach which is standard, or objectively better?
>
>
>
> Thanks,
>
> Marcin
>
>
>
> *Marcin Tustin*
> Senior Software Engineer
>   ------------------------------
>
>
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>
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-- 
------------------------------
Harry J.W. Percival
------------------------------
Twitter: @hjwp
Mobile:  +44 (0) 78877 02511
Skype:         harry.percival
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