[TIP] [mock] Mocking referenced methods?

Gary Bernhardt gary.bernhardt at gmail.com
Mon Oct 3 13:10:38 PDT 2011

STUFF is created at class definition time, before your patches are
run. The patches are successfully patching the method, but STUFF
already holds a reference to the original, so that's what's getting


On Mon, Oct 3, 2011 at 12:14 PM, Tom Davis <tom at recursivedream.com> wrote:
> First off, sorry for the vague term "referenced methods"; I don't know the
> proper term for this. Basically, I cannot seem to mock a class method by
> name if it is being called as a reference from another attribute. If that
> still makes no sense, here's an example:
> import mock
> class Foo(object):
>     def meth(self):
>         return True
>     STUFF = ((meth, True),)
>     def do(self):
>         for m, r in self.STUFF:
>             assert m(self) == r
> f = Foo()
> f.do()
> with mock.patch.object(f, 'meth') as meth:
>     f.do()
>     assert meth.called
> with mock.patch('__main__.Foo.meth') as meth:
>     f.do()
>     assert meth.called
> This example is a bit contrived, but should get the point across. I believe
> I understand why the former doesn't work (I need to explicitly call "meth"
> with "self", thus it isn't an instance attribute), but I don't understand
> why the latter doesn't work, either...
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