It's not uncommon to have a regression test for compilers that are written in their own language (e.g. some C compilers): compile each new version with itself, then use that to compile itself again, then use the result on unit tests or whatever, which should yield the same results as before.

The point being that determinism of a particular form is expected and required in the instances where they do that.

(I'm not arguing for or against that, I'm simply saying I've seen it in real life projects over the years.)