This is a little off, unless you give “unit” a very different term than most use it. The term unit vs division tests are used in the military, so a unit test is to check combat readiness of a unit and division tests is the combat readiness of a division. The books that use that term mostly come from US Artillery documentation.

I wonder if the etymology of modern unit testing does come from that; but if it did I’d assume the other terms would exist too.