I agree with that but I would say that if I required formal verification of that kind I would move the proof based rationale into the type system to provide those checks.
I would add Tests can be probabilistically exhaustive (eg property based testing) and answer questions beyond what proof based reasoning can provide ie. is this sorting of arbitrary strings efficient and fast?
I would add Tests can be probabilistically exhaustive (eg property based testing) and answer questions beyond what proof based reasoning can provide ie. is this sorting of arbitrary strings efficient and fast?