Comment 1 for bug 906251

I'm not 100% sure that this would be a desirable feature for core testtools.

However, if you're interested in doing this for Launchpad, you could do this override in your base TestCase:

  def _run_test_method(self, result):
        ret = self._get_test_method()()
        self.assertIs(None, ret)
        return ret

The API isn't public, so it's liable to change without concern for backwards compatibility. However, it would do the job.

This is also the first actual use case I've seen for bug 584824.