Obvious code should have obvious properties, in which case you should be able to gain value from property tests. If you make every little function high-quality

Obvious code should have obvious properties, in which case you should be able to gain value from property tests. If you make every little function high-quality and well tested, you should end up with better code overall. The only functions, IMO, that don’t deserve properties as much as functions which are exclusively the composition of other functions without any other logic. In that case, the function is often, by definition, its result.