Omeka Test Install?

I'm developing an Omeka theme, and I'd love to have a test install filled with dummy items, exhibits, etc, so that I can test a number of different use-cases for my theme without having to manually create it all. Does something like this exist?

Not really, but you could use the API Import plugin to copy most of an existing Omeka 2.1+ site if the API is open. You can also use my demo site's api endpoint to copy some content and exhibits. It won't cover all the use cases you'll probably want to check, but it will at least be a start