Ok, TDD didn't help with designing an algorithm for Lychrel number - because you just don't get around implementing the loop that tests if a number is a lychrel

Ok, TDD didn't help with designing an algorithm for Lychrel number - because you just don't get around implementing the loop that tests if a number is a lychrel number, and it's very simple. But to me that's not the whole purpose of unit tests - the most important part for me is that it tells you very quickly when you have bugs in your implementation. Somehow the author neglects to address this very central point.