This code is the solution to a blog post I did on Test Driven Development with Apex, which can be found here.
Demonstrates using a TDD approach to an easy to understand problem - converting roman numeral strings into Integers.
Each version of the classes show the iterative "Red, Green, Refactor" approach of TDD.
I have completed the first five versions of both the test and implementation classes. Try fixing the failing test in each class by changing the implementation logic until the tests go green, then move on to the next version of the class.
If anyone wants to fork this repository and add some more scenarios, feel free. Send me a pull request and I'll add your code in.
Any questions, fire me a message on Twitter