A quick piece of code using James Shores video series on TDD to create a few recursive objects that pass a value along.
http://www.jamesshore.com/Blog/Lets-Play/Lets-Play-Test-Driven-Development.html
From a series of pieces of code I've built to investigate Test Driven Development and Domain Driven Design
https://github.com/Techbot/bdd-domain_driven_dungeon_design
https://github.com/Techbot/bdd-StrategyPattern-TwoEnginesBy3Weapons
https://github.com/Techbot/bdd-CompositePattern-ArmyandUnits
https://github.com/Techbot/bdd-DecoratorPattern-TotalStrength-3-sources