Could you flesh that out a bit, so we know you're not just spamming?

It's hard not to see that as a list of clients of consulting firms rather than a list of serious open source software built with TDD.

I know the Rubinious project was built aiming to use TDD and it doesn't seem to have gone anywhere YET. As far as I can tell, a compiler is one beast that needs a strong abstract design first rather than a set of tests first - but I'm prepared to be surprised.

Pivotallabs lists Twitter first but I would be rather surprised if someone could verify that a substantial part of Twitter's app has been built using TDD (go ahead, surprise me).

One of the comments on the original post claims open source apps don't count because they "are not subject to many of the challenges the average developer faces in a corporate environment" so it appears TDD fans can't win either way.

But since you're looking for open source success stories there was some very positive noises about TDD from a Twisted dev recently:

"I would strongly recommend at least practicing some TDD, too. Learning how to write tests was useful for me, but practicing TDD really expanded my design skills in a bunch of surprising directions that were almost unrelated to testing. I originally felt as you do, that I wasn't disciplined enough to do it; now I feel like I'm too undisciplined not to do it ;-)."

From: http://glyph.twistedmatrix.com/2009/09/diesel-case-study-in-...

Though he specifically states that Twisted didn't start out TDD, which he regrets, but maybe that disqualifies it.

Regarding Rubinius (and JRuby that was listed in the original post) I'm not sure trying to create a spec for an existing language implementation and then try to meet it would count as "true" TDD if people care about such differences. But maybe they do TDD for other bits lower in the stack, I'm not sure.

Well,

I've only scanned the Rubinius code and noted their blogs/announcements but ... it seems like they shifted from one basic model of their virtual machine to another in the middle of their process and I'm quite skeptical that this either indicated they doing well or that it would be considered a victory for TDD. Looking from the outside, it looked more like "we thought that TDD would let us get by without design but we were wrong...".

I've heard TDD described as "write a test, write a function, repeat" and THAT is not enough. You definitely need a guiding design as well.

I worked as a consultant at Twitter for a while [summer 2008] and saw no evidence of TDD in action. More like - someone monkey patch the running server, we're on TechCrunch again!