Question

Given the following simple example:

class MathObject(object):
    """ A completely superfluous class. """ 
    def add(self, a, b):
        return a + b

    def multiply(self, a, b):
        result = 0
        for _ in range(b):
            result = self.add(result, a)
        return result

Obviously, multiply() calls add() internally. If add fails, multiply() fails too. In a complex enough class it might be really complex to find out why exactly a unit test failed.

How does one unit test methods/objects/parts that have dependencies?

Answer 1

I usually just let them fail – classes should be simple enough to spot the bad test fast.
But, in complex cases we’ve used simple naming conventions for tests to make sure a certain order is kept (def test_00_add, def test_01_multiply).

Again, if your classes get big this will be harder to manage, so just don’t get them big 🙂