Another day, another
argument discussion with a colleague over the common misapprehension that you can have a process with discrete requirements capture, design, development and test phases, yet somehow still claim to be agile. Once again, I tried (with limited success) to explain that you don’t need to do all your designing up front before you start writing code, and that starting to write code almost immediately isn’t ‘hacking’, provided that you are continuously paying attention to good design as you go.
In other words, agile developers do just as much designing as those still following waterfall methods, but we do it at the same time as writing the code.
Reflecting afterwards, I realised that I’ve been phrasing the message the wrong way. As anyone who really ‘gets’ test-driven (and particularly behaviour-driven) development knows, it’s not really about the testing, but about the design process. A waterfall ‘designer’ starts from an understanding of the problem and builds up some kind of model for a solution, which they then pass on to the implementors An agile developer does exactly the same, but the language they use for the model happens to be executable source code rather than documents or UML. This choice of modeling language has the rather large benefit of being testable, and once your design is finished, you’re done. No need for someone to try to interpret and implement it. No scope for misunderstandings between designer and developer. No danger that the design is incomplete, or that part of it turns out to be unworkable.
It’s not that we start writing code and design as we go along.
We are always designing – we just write the code as we go along.
[tags]agile, tdd, bdd[/tags]