Now that rspec runs under jruby, and with a few hours to spare, I thought I’d have a play.
[Update:] I’ve simplified the import of java.util.Date following a suggestion in a comment (from Charles Oliver Nutter, no less!). I also noticed that I wasn’t using rspec’s setup properly (or at all), so I’ve tweaked the samples a little. I haven’t got the code here to try out, so there may be typos.