Comment 5 for bug 98431

I did some work on this 6 years ago, in the test-checkers branch of zope.testing in SVN:
http://zope3.pov.lt/trac/log/zope.testing/branches/test-checkers

The end result was functional, but I gave up while trying to write a functional doctest for it, IIRC. Therefore it was never merged, and then lost during the zope.testing.testrunner -> zope.testrunner renaming and subsequent git migration.