IronCow is a library that wraps the Remember The Milk (RTM) web services. The “upper layer” of the IronCow API is an object model that stays in sync with the server and is designed with data binding in mind. Of course, one of the things that went into IronCow’s design was testability. IronCow ships with a suite of unit tests that, well, test that the API is working fine. However, there’s another testability aspect: how the clients of your API are going to test their stuff.