[digibo]

Personally, I think unit tests shine best when you're designing an API. I can swing from hate to love and back about TDD in minutes, but when it comes to thinking about how your code will be used, unit tests (did we stop using that term?) are a tremendously useful tool I have.

I guess if all code written could be seen as an API, TDD would be great, but that's not the world I live in.

[mjevans]

This is why I prefer free to implement open standards that are (hopefully) well designed and specific.

Inter-operablility and interchangeability of parts means that it's possible to validate an implementation to at least some degree.

The best example that I can think of off the top of my head is the OpenGL 4.4/4.5 work that is nearing conformance for the Mesa3D project ( https://en.wikipedia.org/wiki/Mesa_(computer_graphics) ); while the functional coverage for the main modern drivers is 'complete' the official conformance testing has already resulted in some bug fixes and additional areas to focus on improving.

That real life case study is yet another example of how an API and conformance tests built around that API result in better code and in a more consistent experience that isn't dependent upon a mono-culture implementation.

[westurner]

> I guess if all code written could be seen as an API, TDD would be great, but that's not the world I live in.

If not an "Application Programming Interface", isn't all code an Interface? There's input and there's output.

With Object Oriented programming, that there is an interface is more explicit (even if all you're doing is implementing objects that are already tested). There are function call argument (type) specifications (interfaces) whether it's functional or OO.