I only got to the first stage. I was asked to live code an URL shortener. This would have been easy to do, if it weren't for the fact that the entire code had to be done following TDD. This was never mentioned, neither in the screening nor in the job description. I am quite rusty with TDD so naturally I failed the test. However, it is quite disappointing that a company of this size would not give a clear explanation of what to expect. Particularly, if you are using a technique that is not common and you expect candidates to be acquainted with it.