How To Use Patch to Modify the Value Returned by a Method in Pytest

Question

I can use patch to change the side effect of a method on a object. But is there a way to get the value returned by the method, modify it, and then return that object. E.g. something like

@pytest.fixture()
def foobarbaz(mocker, obj):
    
    def side_effect(obj)
        ret_val = obj.bar()
        ret_val.pop("key")
        return ret_val

    mocker.patch("foo.bar.baz", side_effect=side_effect)

So that all that I'm doing is guaranteeing that the return value doesn't contain the specified key.