[TIP] unittest2 plugins

[jason pellerin]

> As for handling custom outcomes using skiptest... Currently the onTestFail
> event is not raised for skips, expected failures or unexpected successes.

I'm afraid my explanation wasn't very good. This is actually the
opposite (in a sense) of the functionality that's missing. What nose
can do with custom error classes is allow a plugin to treat *any*
exception like a skip. That is, say your app under test may see
IOErrors from a 3rd party service and you don't want those tests to
fail, you want to essentially skip them under a different label. With
nose you can register a handler for IOError and make it treat those as
skips instead of errors, and also output something different in the
dots. I don't see a way to do that with the current set of hooks in
unittest2.

I hope that's more clear?

JP