There's been a big industry focus on test driven development over the past few years.  Many advocates of TDD make it a point to say that TDD is not really about testing, it's about design.  Writing tests before application code forces you to think about the goal(s) of the application code.  For example, what should the input to a certain method be, and what output should it supply?  TDD forces you to think in terms of inputs/outputs and code interaction.  What input should be provided to the callee, what output should be provided to the caller - essentially, how will multiple objects (e.g. classes, methods, etc) interface.  

I've recently started practicing TDD a bit, and have found that instead of always writing unit tests with some type of testing framework (e.g. nUnit), I sometimes create a console application that calls certain methods and reveals the output.  Granted, these are perhaps more "integration" tests than unit tests, as I'm using them to view database contents.  None-the-less, it got me thinking about TDD, and the notion that "Test"-Driven development isn't really about tests.  In my opinion, a more appropriate name might be "Client"-Driven Development.  I'm not referring to the clients that pay your bills, but the client portions of your application (e.g. the UI which calls another application layer).  There are clients at every layer of your app - the UI calls one layer, that layer calls another layer.  Each caller is a client, and when writing tests first, we need to think in terms of the "client", what it should input, and what the result should be.

Isn't CDD essentially the goal of TDD?