At work we've been belatedly adding a lot of unit testing following a massive refactor of our main product.
It's a pain in the ass, boring, and has led to me spending entirely too much time on HN instead of me writing the 500th test that checks if a DbEntityException is thrown, but it's almost done so good riddance.
I burned out because what started as a selfish dog-fooding utility became this vision less beast filled with feature requests from strangers.
The reboot is now tightly scoped to what I want and only what I want. Once done I slap a price on it and call it feature complete.