Because 3000+ is a lot of unittests, but i know in my heart of hearts that there is much uncovered code waiting to be found *cough* dav *cough*
I'm also amazed by the amount of unit tests in feedparser project which definitely must have smaller code base than twisted. It brings some confidential for the module, for sure.
Hmmm, not to detract from FeedParser's test coverage, but even though the author calls what it has "unit tests", I think they are more like acceptance tests. A unit test exercises a single unit. FeedParser's tests parse complete sample inputs, exercising much more code than a single unit at a time.Still, that's an awesome amount of tests, particularly, as you say, for such a small code base. It speaks both to the attentiveness of the author and the amazing range of complexity and confusion around XML and RSS. :)