UncleBob's Three Rules of TDD

This was one of the three TDD cards I posted while at Object Mentor. A more attractive set of hand-drawn cards then appeared (with full attribution) at Brian DiCroce's site a little while after. I still wish I'd drawn them first. The other have been presented here: FIRST principles and our site's most popular card to date, the Red, Green, Refactor card.

These three laws originated with Robert "Uncle Bob" Martin, who has provided such a wonderful write-up that there is no value I can add other than shrinking the sentences to fit on a card. Bob is a great guy and a solid techie. And by solid, I mean SOLID.

By the way, I've submitted a paper to Agile2009 to do a little session on doing "in a flash" teaching sessions with index cards. If it's accepted, I'll see you there.


  1. i have a humble request: please use another font within your images. comic sans is gross, it makes me hurt inside. don't just do it for me... do it for the kids.

    STAY A/G/I/L/E

  2. What would you like to see? I'm considering hand-lettering each one, but Jeff has preferred a text font in the past. We'd like something that isn't too "texty", if you know what I mean.

  3. hand-lettering would be great... it always has such a nice character (depending on your quality of penmanship). another option might be something serify like courier / american typewriter.

    you could reach a compromise with something like:


    good luck! keep it up!

  4. We had some fonts that looked handwritten in the past but couldn't come to consensus on one. I figured Comic Sans was a temporary measure, and now that we're prodded, Tim went and found the J.D. font. My next card will feature it (if I can find it...). Thanks for the poke!

  5. There is a good TDD article on http://www.typemock.com/Test_Driven_Development_TDD.php

  6. I love Comic-Sans. Ignore the text-trolls!


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