Mocking a module imported inside of a function

Question

Is it possible to mock a module that's imported inside of a function?

for instance

def my_func(input):
    import something_else
    something_else.do_something(input)

I have an import inside of the function because of a circular dependency. Based on my googling I think I am SOL, but was wondering if anyone knew of way to make this possible.

I just want to verify that do_something gets called.

score 5 · Accepted Answer · edited May 23 '17 at 11:44

5

You can use the same technique that's described in this answer. In short you can patch sys.modules dict. So your test can be:

from unittest.mock import patch, MagicMock

...

def test_call_do_something(self):
    m = MagicMock()
    with patch.dict("sys.modules", something_else=m):
        input_mock = MagicMock()
        my_func(input_mock)
        m.do_something.assert_called_with(input_mock)

You can rewrite it by patch decorator, but m should be a static instance.

edited May 23 '17 at 11:44

Community

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answered Dec 11 '15 at 12:52

Michele d'Amico

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Thanks for the tip. Didn't know you could do that. How would this example change if instead of importing something_else, the import statement is `from some import thing_else`? – aamiri Dec 11 '15 at 17:57
You mean that you have `from m import a` in a function? I can cover it later in the WE. – Michele d'Amico Dec 11 '15 at 18:42
If I understand correctly It should work either in these cases. – Michele d'Amico Dec 11 '15 at 18:57

Mocking a module imported inside of a function

1 Answers1