Need-Driven Development

I recently came across a 10 year old article titled “Mock Roles, not Objects“. I recall reading this article at some time in the past, but I guess that I really didn’t get it the first time. This article is awesome, and I recommend reading it. But maybe like me, you need to become fairly familiar with TDD and using mock objects before it will have much impact on your thinking.

When I reread the article, I was immediately struck by the opening 2 sentences:

“Mock Objects is an extension to Test-Driven Development that supports good Object-Oriented design by guiding the discovery of a coherent system of types within a code base. It turns out to be less interesting as a technique for isolating tests from third-party libraries than is widely thought.”

Wow. The article then goes on to explain how the proper use of Need-Driven Development can help in the creation of good, clean architecture. I think that maybe the first time I read this article, I was still stuck in creating relatively few, large objects with lots of methods. After repeated viewings of Uncle Bob’s videos though, I changed my mindset to using lots of small, SRP compliant objects. Without that mindset, it might be possible to misinterpret this article as recommending the use of partial mocks to intercept calls from one method to another within the same object. Been there, done that, got help and am hopefully on the road to recovery now.

I think that there are still parts of this article that I’m not evolved enough yet to fully grok, for example section 4.1. I think I’ll come back and reread the article in another year or so and see if I get it then.

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