A Green Rubber Band

Bob Martin now wears a small green rubber band. His explanation:

I wear a green band on that I put on about six months ago. This band is a statement of professional ethics. The band signifies that I unit test my code and I know it works.

— Bob Martin SD West 2006

Bob went on to explain that testing 50% of your code isn’t enough that the target should be 100% or at least the high 90s. Do you really want to explain to your customer that you only know that half your code works.

I like the little green band idea, as an obvious visual. I’m not sure it will catch on in the general TDD world, but I like that Bob’s still focusing his considerable presenting skills on convincing developers to test.