Well, I used to just let the test pass with the 'return' statements below.. but that was disingenuous.

There are a set of tests in fedmsg_meta_fedora_infrastructure that test each one of the processors for each of our message types.  If I have a test for a bodhi message and declare that: 'the bodhi message processor, given this message, should return 1) this URL 2) this list of packages and 3) this list of usernames' but I don't specify what dict of emails it should return, I don't want that test for emails to *fail*.  The code that test would have tested did not actually fail.  It's that the test case was underspecified -- I don't actually want to go through and test that every message processor for every message type returns exactly the same mapping of usernames to fasusername@fedoraproject.org.  And so, we skip -- indicating that "this could have been tested, but wasn't".

This gives us a better idea of test coverage at first glance.  It doesn't lie and say that tests pass that weren't actually run.  But it also makes the test developer's life easier by not requiring him or her to write redundant tests -- they may be omitted.