It stands to reason that the tests in simpletest/tests will be the ones that people will use to base their own tests. These tests were written by at least 5-6 different people, and it shows. As a result, it's really confusing for a new developer to get a sense of what your own module's SimpleTest integration ought to look like.
Thanks to the hard work and good comments to everyone here, this page has been moved to drupal.org and promoted as our "official" Test writers guidelines.
