I tried it with mocked functions instead of methods and got the same result, so I dug into this a little deeper. It seems as though the issue it how the mocked functions are called. If I replace the do_something() line with the following then it works.

#do_something()
manager.set_foo_func(3)
manager.set_bar_func(4)

I am a beginner with unittest so please let me know if I am just using this incorrectly. However in the original code I posted, if I print(manager.set_foo_func.mock_calls, manager.set_bar_func.mock_calls) I get the calls made in do_something(), however print(manager.mock_calls) returns an empty list which leads me to believe something else is wrong.