Rails 3 + DataMapper - database not created/destroyed between tests

Question

I'll try here since the mailing list for DM doesn't seem to have much input from other users unfortunately.

I'm reasonably sure this isn't something we have to do manually, but maybe I'm wrong. I've removed ActiveRecord from my project and have started creating models in DataMapper. It's all working, but I want to write unit tests for my models (and functional for my controllers). However, my test database is not cleaned between test runs (easily proven with a test). AR takes care of this for you, but it seems like the DM guys haven't considered this in their dm-rails project.

In a desperate attempt to wipe the slate clean, I dropped all tables in my test database. Now instead of my unit tests failing because the environment is dirty, they fail because the schema doesn't exist. Looking at the rake tasks available to me, I cannot restore my test DB without also wiping my development database. I'm starting to go insane and hoping a fellow DM + Rails 3 user can nudge me in the right direction.

Specifically, when I run my unit tests, all test data should be removed between the test methods. Also, if I make a change to the schema, I should be able to run my tests and they should work.

I tried putting DataMapper.auto_migrate! in a setup callback in my test_helper.rb, but this doesn't seem to create the schema (the tests still fail due to the tables not existing when they try to insert/select records).

I've seen https://github.com/bmabey/database_cleaner, but do we really have to bring an external library into Rails just to do something that DM probably already has (seemingly undocumented) support for? This also doesn't address the issue of recreating the schema.