Automocking for Python?

Question

I'm used to using AutoFixture.AutoMoq with C# and wanted to know if something similar is available for Python. I'm not using django or databases, so django-autofixture is not going to help me.

What I'm looking for is something that cuts down on the code I need to write to setup all my interrelated objects with stubs/mocks for testing. I'm using the IoC pattern for design (but no DI framework since Python doesn't really need them).

I'm using Nose and Fudge.

Answer 1

Try looking at Mock

It allows you to mock out classes

from mock import Mock
mock = Mock()

Patch functions

from mock import patch

@patch("package.function")
def test():
    do_stuff()

And then assert how many times that you've called a function

mock = Mock()
mock.foo()
mock.foo.assert_called_once()

So say you have a class structure as you describe.

class A(object):
    def __init__(self, class_b):
        self.class_b = class_b
        ...

class B(object):
    def __init__(self, class_c):
        ...

...

Then if you want to mock out A

In [2]: import mock

In [3]: mock = mock.Mock()

In [4]: a = A(mock)

In [5]: a.class_b
Out[5]: <Mock id='21280080'>

Going down the line:

In [6]: a.class_b.class_c
Out[6]: <Mock name='mock.class_c' id='21281488'>
In [7]: a.class_b.class_c.class_d
Out[7]: <Mock name='mock.class_c.class_d' id='21051984'>

It will all be mocked out for you regardless of how tight you've coupled your code. I imagine there are similar ways to do this for Fudge