If you look at Mingle, the project management tool we’ve been working on… On that tool I happen to know that their test base is twice as much as their code base. So, two-thirds of the code in that product is tests, and that allows them to do quite violent things. I know that a couple of months ago they made a very fundamental change to the database scheme. I mean, we’re talking, utterly to the guts of the database scheme. And they did that and… it wasn’t even an event worth talking about. And, when they were planning to do it they were saying ‘Yeah, yeah, we’ve got to fundamentally alter the core tables in this application… Yeah we’ll do that, and it’s not a big deal.’" -Martin Fowler (paraphrased)