Match mock.patch decorator with appropriate param

Match mock.patch decorator with appropriate param

mock.patch and mock.patch.object can be used as decorators for mocking
within the scope of the function they decorate. When there are multiple
decorators it is important the function parameters relate to the
corresponding patch objects i.e. that the parameter order matches the
decorator order.
It is easiest to explain this with an example:

@mock.patch.object(Foo, 'bar')
@mock.patch.object(SomeClass, 'some_method', some_function)
@mock.patch.object(AClass, 'a_method')
def test_some_stuff(self, mock_a_method, mock_bar):
    pass

So the decorator closest to the function definition must correspond to
the first (left-most) patch parameter. Note, if the decorator is given a
third argument, the kwarg new, then the decorated function is not
passed an extra argument by that decorator.

Change-Id: I035d71cb3b81f0c8bfd83ed81d8426cb0df31c90