As a test dev, I'm really interested in this (and in inference engines/languages like Prolog). How can I write code that has the best chance of finding bugs that customers might care about? Short of wrapping humans in APIs (and I also love that), we can write tests that are different every time to try to avoid "stale" tests and approach the diversity that humans exhibit. Probabalistic computation has that built in! A lot of manager-types want a "repeatable" process but I'd like an "easily, know-ably mutable" one. One with known bounds even if the actual inputs/results weren't the same every time.

If your unit tests were automagically varied wouldn't that make them more valuable? They might actually find new bugs once in a while.