In this TDD video I linked to, Ian Cooper mentioned that there were a series of videos where Kent Beck, DHH, and Martin Fowler debated TDD and related practices. The first one is here, and there are several more that you can see linked from that one. There are six in total—each about 30 minutes long. The debates were sparked by DHH’s blog that TDD was dead.

One interesting thread throughout is the idea of tradeoffs, and that nothing is necessarily always good or always bad. I had written this before in the context of technical debt and personal savings rate.

In these debates, they discussed whether more testing was always better and whether faster tests were always better. And of course, the answer is: it depends.

With no (or low) tradeoff cost, then yes, more and faster tests are better. If I can make tests faster with just hardware upgrades, then that’s great. Also, when benefits are very high, then even higher costs may seem low. For example, if tests take an hour, then we are willing to bear high costs to make it a few minutes. We would bear some lesser cost to make it a few seconds. But, should we keep going?

I think this all fairly obvious, but in the heat of discussion, it’s often glossed over.

(I should say that I believe for lots of kinds of problems, testing and coding together, whether it’s TDD or or not, makes you go faster and more correctly. I also mostly don’t care about unit isolation if it gets in the way—if you aren’t going faster and more correctly with tests, then I’d start wondering why and whether they might be getting in the way).