Sorry, you're right, I just confirmed that it no longer works. I'm pretty sure that method worked just a few weeks ago though. =\ The changes are probably related to the test user overhaul that Facebook has been working on for the past few months. https://developers.facebook.com/blog/post/429
I'm glad they made the new system -- it looks really clean and useful. I just wish they hadn't left the old system halfway operating, so you can fall into it but not climb out.
And they really, really need to edit that blog post to point people to the new system. It is in the top place of the google results for "Facebook test account," and I'm sure it is misleading a lot of people. At the least into using the clumsy old system, and at the worst into destroying their accounts.
