The value of unit tests when creating software is perhaps debatable, but I find their greatest value to be in maintaining software. If you lock in your expectat

The value of unit tests when creating software is perhaps debatable, but I find their greatest value to be in maintaining software. If you lock in your expectations of a software component, when it's time to make changes (due to shifting requirements or what not), you can add tests capturing your intent and make sure that you aren't breaking existing expectations. Or at least, that you know which expectations your change will break.