In unit tests, do we test Super classes too?

I have a situation where class under test has a method which does return super.delete(obj); so while writing unit tests with Junit & Jmockit, should I mock return value of return super.delete(obj); or keep going up above the hierarchy. Actually, this super call keeps going up to three four levels in inheritance hierarchy. I am just confused if it still remains a unit test if I step into super classes.