Interesting, could you show me a formal proof that can't be expressed in logic (ie. code) and then tested?
My thought here is that since proofs are logic and so is code you can't have a proof that can't be represented in code. Now admittedly this might look very different than typical say JUnit unit tests but it would still be a test validating logic. I am not saying every system is easily testable or deterministic but overall, all else equal, the more tested and testable a system is the better it is.
IME things that are very hard to test are often just poorly designed.
My thought here is that since proofs are logic and so is code you can't have a proof that can't be represented in code. Now admittedly this might look very different than typical say JUnit unit tests but it would still be a test validating logic. I am not saying every system is easily testable or deterministic but overall, all else equal, the more tested and testable a system is the better it is.
IME things that are very hard to test are often just poorly designed.