Object Design: Roles, Responsibilities, and Collaborations Book

Rebecca teaches here her method to design object-oriented systems. She focuses on roles, responsibilities and collaborations. We first identify candidates objects, possible roles, and likely responsibilities. Then, we assign these responsibilities to our objects or roles and we refine how these objects collaborate and how they control each other. While I completely agree with the importance of roles and responsibilities, I do not see how the method fits more modern agile practices such as test-driven development, where the design emerged from repeated refactoring of the code base.