Exploration Through Example

Example-driven development, Agile testing, context-driven testing, Agile programming, Ruby, and other things of interest to Brian Marick

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Sun, 09 Mar 2003

What would Plato have thought of test-driven design?

Running through conventional software development is a strain of Platonic idealism, a notion that the "upstream" documents are more important, more true, more real than the code. The mundane final product is like the shadows on the wall in Plato's allegory of the cave, so software development is the process of adding progressively more detail that's progressively less essential.

As I understand it, test-driven design is swimming against that current. For example, there's a discussion of creating a board game test-first on the the test-driven development group. William Caputo writes:

So, I don't start with a story like "The game has Squares" I start with something like: "Player can place a piece on a square."[...]

What I am not doing is worrying about overall game design. [...] [Ideally], I let the design emerge.

I'm not a huge fan of the rhetoric of emergence, but I want to note the shift in perspective here. William does not appear to be concerned with capturing the essence of "Square", with finding the right model for a physical game in software, but rather with allowing some action to be performed with something named (for the moment) "Square".

From this perspective, it does not matter awfully whether any single person has correctly apprehended, nor correctly expressed, the essence of the problem or the solution. We can even remain agnostic about whether such an essence exists, whether there are a set of requirements that we could ever "capture".

Next: The Gathering Storm

## Posted at 14:07 in category /agile [permalink] [top]