Who Should Write Tests?

The whole "programmers are no good at X" argument, even coming from other programmers is getting tiresome.

Nobody is yet good at things that they don't know how to do. That's what practice and learning are for. The implication that non-programsmers will somehow be better at practice and learning of things like interaction design is just bunk. It's like saying that blacksmiths can never be good pastry chefs.

I mean, have you tried a pastry made by a blacksmith? The only difference between that example and interaction design by programers is that sometimes programmers are forced into trying, even though they aren't given any education or support in that realm.