Spy chained functions in Python

Asked May 25 '20 at 16:48

Active May 25 '20 at 16:54

Viewed 63 times

I am trying to unit test a function that is calling two other functions internally. It looks like the following

class A(BaseClass):
    def functionA(self, var_a, var_b):
        return self.another_fn_a(var_a).another_fn_b(var_b)

another_fn_a and another_fn_b are part of the base class that this class is extending and return the same class itself.

Now, I am trying to test my functionA to see that its calling the other two functions with the right argument. I am able to spy on another_fn_a, but the spy on another_fn_b doesn't seem to be working. My test looks like the following

def test_will_funcationA(mocker):
    test_obj = ClassA()

    spy_a = mocker.spy(test_obj, 'another_fn_a')
    spy_b = mocker.spy(test_obj, 'another_fn_b')

    test_obj.functionA("var_1", "var_2")

    spy_a.assert_called_once_with("var_1")
    spy_b.assert_called_once_with("var_2")

The first assert seems to be working, however, for the second assert I get Assertion Error saying that another_fn_b wasn't called.

What am i doing wrong here?

edited May 25 '20 at 16:54

asked May 25 '20 at 16:48

aakashgupta.0205

What does `another_fn_a` return? Does it return `self` or some other object? – Mark May 25 '20 at 17:05
it returns another object of type `BaseClass`. So does `another_fn_b` – aakashgupta.0205 May 25 '20 at 17:31
So then `test_obj.another_fn_b` actually isn't called. – Mark May 25 '20 at 17:32
then how do I check that `another_fn_b` is being called? – aakashgupta.0205 May 25 '20 at 17:34
i tried `spy_b = mocker.spy(test_obj.another_fn_a("var_1"), 'another_fn_b')`. But that doesnt seem to be working either – aakashgupta.0205 May 25 '20 at 17:36

Spy chained functions in Python

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