* Why is the Perl testing infrastructure so effective?

Because Schwern made it that way, and it was good. :)

* If I wanted to export some of the qualities of Perl testing to a non-Perl product, what should I focus on?

Getting Schwern or Ovid interested in that product. That's most effective when you change the product to be World of Warcraft, I think.

* What motivates a (QA) contributor?

If you're asking how to get people to work for free, well, there is no answer. It's different for every person. If you're assuming that you will get work for free, I think you're already off to a bad start. iPods might be interesting, but they aren't all that special or expensive to make most people do that much work. If the product is really useful and people like it enough or think they can't live without it, they'll help with it.

I contribute to open source because I'm too stupid to realize that for the same pay I could watch TV all day, get through my Netflix list, or maybe read a book. :)

Update: I wrote this post just before going off to bed, and then laid in bed thinking about it and that it probably is more flippant than I mean it to be. Writers should be given free prescriptions of sleeping pills for this very reason.

I think things such as Perl's testing culture congeal around a few alpha personalities. There's no scientific reason these things happen, and a lot of it is by accident. I created Test::Pod because I could. It was easy and it was fun. From that, Andy Lester got interested, and eventually created Test::Pod::Coverage, and eventually took over Test::Pod. Both of those ended up as CPANTS metrics. Although it pains me to say it, I think Malcolm Gladwell's The Tipping Point applies here. That's not a perscription for success. It just points out that some things succeed for no other reason than somebody does it and somebody else likes it enough to do it too. For every time that happens, though, many other things don't catch on. I've written plenty of test modules, but I bet most people can't name any them. Test::Pod is the one that made it.

Perl's testing culture matured at a particular time. Test had been around for quite a while, although most CPAN contributors seemed to find it just as easy to print "ok $test\n"; as use a module. Test::Simple did what a lot of people were thinking they should do, but didn't: write an ok function. Schwern actually did it though, and there were plenty of other people around who were waiting to use it. IF he had made it earlier, maybe it would just be sitting there on CPAN collecting dust. Who knows.

Update2 Foro stvn: sure, there are a lot of people involved with testing now, but I credit Schwern with starting the whole thing. All that stuff you mention came later.