As I recall, Rubinius did things like attempt to document the Ruby Language through a series of test suites rather than the standard formal methods (Edit: they did have the quandary that Ruby had without much exact specifications but still, no number of test by themselves can formally capture a language).<p>Having play with "Test Driven Development" just a bit, I feel like it tended to involve a lot of arrogant posturing with a flavor of "who needs design, who needs formal specs, if you've got the balls to write test and dive into the code, you can do anything without knowing anything".<p>It's not entirely unpleasant to see such reasoning break on the shoals of reality.<p>Edit: This sounds mean spirited but it seems like tail of the problems of 2007-8 programming styles.