gistfile1.py

>>> from my_klass import my_klass
>>> from mocker import Mocker
>>> mocker = Mocker()

# Prepare the mock methods
>>> target = mocker.mock()
>>> target.method1(12)              # doctest: +ELLIPSIS
<mocker.Mock object at ...>
>>> mocker.result(5)
>>> target.method2(12)              # doctest: +ELLIPSIS
<mocker.Mock object at ...>
>>> mocker.result(7)

# Now use the mocked methods when testing method3
>>> mocker.replay()
>>> my_klass.method3.im_func(target, 12)
12

Not so keen on how method3 is called. Luckily, doctest is not the only option for Python unit testing.