Unfortunately subclassing core components is the *intended* mechanism for customising unittest behaviour. Changing this is possible, but is a big job with very extensive changes.

I don't think this request is *invalid* per-se, but it isn't something that we're about to change and there are much higher priorities for providing customization points for unittest. Closing as wont fix, but eventually hopefully it will be possible to do without requiring changes in unittest.

(And it *can't* be fixed in Python 2.6 or 2.7 as it isn't a bug and no new features are being added to these versions - so I've changed the tags even though I'm closing it.)