Override the equality operator in your Ruby classes
Test driven development by example is a wonderful book. It could only be better if the examples were all in Ruby :). Mostly, it is pretty easy to convert the code to Ruby if you have some experience.....equality though, can be a little tricky to override if you are relatively new to the language. Fear not, because I've just blogged about how to override the equality operator in ruby, at the same time, throwing in some extra goodness of test driven development.