test first with Ruby

I wrote a tutorial about coding test first for ibm. Hopefully, it’ll help more people start writing code this way.

See more progress on: test first all the time

Update: By the way, I did a lot of the organizational/background work of this using BackPack, which I'm still really enjoying. I'll need to get a bigger review up later, but something a bit more urgent is taking up my time at the moment.