Yet Another Entry From The Peanut Gallery (Score 1)

Well, I have to say that everything here seems to make sense. Personally, I use a not-quite-purist version of extreme programming, in which I write unit tests like a madman. I also take the approach that everything I write is an API that will be used by others (even if it won't because I know I'm just stupid enough to forget how I coded something months ago, and introduce some misuse of it). If you make sure all of your pieces are air-tight, then you should be okay. Then integration testing is used to test how well the little blocks play with one another.

As far as end-to-end testing, we have a testing staff that takes care of that. We perform load testing that is derived from actual user usage (as captured in the access log files), but that's about it. If we wanted to be really thorough, we could run light versions of load tests in the integration environment to simulate user behavior and see if that breaks things, but we don't currently.