Read this article : http://blog.ploeh.dk/2013/03/04/outside-in-tdd-versus-ddd/

In just a few lines, everything became clear…

I had some confusion about supple design and DDD exactly as described at the beginning of this post and also had the feeling that TDD was not really a design pattern either – quote :

Granted, TDD provides fast feedback about the design you are implementing, but it’s not a blind design technique.

And finally, backing up « my point » to start from the UI to be sure that the client has defined all his functionnal needs to be able to define the underlying model. Thank you!