Comment on Testing on High: Bottom-up versus Top-down Test-driven Development by Johnsmithlucky2012

Wed, 07 Jul 2010 21:57:36 -0700

Good post, Ryan. I do find the difference in outside-in and inside-out philosophies interesting. I recommend reading from xUnit Test Patterns on the topic if you haven't already.

TDD from the outside-in is my preference, but I can't quite express why it feels 'the right way' to me.

I would argue that nothing is working until it's working end-to-end. Is outside-in really slower as you suggest?

Unfortunately, I don't always start at the highest level of abstraction. I'm limited to the highest level that can provide me with rapid feedback otherwise development quickly stops being TDD in my opinion. So, I pretty much always start just below the user interface layer. Does that make me some sort of mutant middle-in TDDer then?