The challenging part of using this model is that we have to be thinking about data from the very beginning. When you code using conventional tools, you can create code for a long time before running it. One of the values of Test-Driven Development is that it forces you to run your code earlier and more requently than you might otherwise. With wiring, if your code is in the workspace, it is running.

This approach to “top-down design” requires symmetry of attention between code and data from the start. This is its own form of discipline, because it forces the whole team to think about data early.