TDD as if you meant it is an advanced TDD exercise conceived of and proposed by Keith Braithwaite. In addition to coderetreat, various flavors of the exercise has been used at a variety of conferences and workshops.
The rules for TDD as if you meant it are:
This is a great activity to use with a group who is already familiar with and is experienced with TDD. It is best introduced in the 3rd or 4th session of the day.
Don't attempt TDD as if you meant it with a group who is not already familiar and comfortable with TDD. Instead, introduce some more basic TDD exercises (such as TDD Ping-pong).
When facilitating TDD as if you meant it, make sure you help pairs follow the steps. Asking questions is usually the best way to do this:
You: Why did you create that class?
Participant: I thought we needed it.
You: Why? Did one of the tests "drive" you to create it?
You: It looks to me like you might be taking too big of a step by creating the class. I suggest deleting the class and trying again.
It may also help to provide a brief demonstration of TDD as if you meant it before asking people to do it.
During the retrospective, help guide the discussion to reveal the primary learning objectives.