I’m currently working on stage 8 of my project plan – "Eradicate hard wired paths". I’ll blog about the gory details later but for now I just wanted to show how the small number of tests I already have in place have proved to be very useful. As part of this work I have introduced a new module – LCFG::Client::FileLocator – which is nearly all new code. Having created this module I started porting over the rest of the client code to using it for file and directory path lookups. As I already had some tests I was able to gauge my progress by regularly running the test suite. As well as showing up the chunks of old client code which still needed to be ported it revealed bugs in 8 separate lines of code in the new FileLocator code. Finding these bugs didn’t require me to write a whole new set of tests for the new code (although that is on my todo list to ensure better coverage). For me that really shows the true value of writing some tests at the beginning of a refactoring process. It definitely produced higher quality code and the porting took much less time than it would have otherwise done.