Awesome, I'd love a pull request! I've been looking at FoundationDB, but haven't had time to test it. Porting the tests to another database is (hopefully) a mostly mechanical exercise.
Here's one way you could run this test vs. FoundationDB:
Just submitted a pull request for FoundationDB: https://github.com/ept/hermitage/pull/1
FYI I'm an engineer at FDB, happy to help.