Quite a while ago I ran across this post (now a PDF periodical article). I’d been doing what I call “change testing” for some time, and I thought this was a good introduction to the concept. Please see the section “Regression Testing” that begins on the second page. (But it’s okay — informative, even — to read the whole article.) I especially like the metaphor that sees change testing as a “quality ratchet.”
But I think it’s unfortunate that the authors characterize change testing as regression testing, which I think invites confusion.
I’ve done change testing on a large scale, and will have much more to say about it in forthcoming posts.