I'm sure there's more to be done, but this gets the pending spec passing, at least. Also eliminates the round-trip to the database to evaluate conditions on a single resource (DataMapperAdapter.matches_conditions_hash?).
At the moment I don't see how to associate this pull request with ryanb/cancan#245 but it is meant as a fix for that issue.
Use dkubb's suggestion for evaluating conditions against a Resource.
Fix pending spec for DataMapper adapter.
Awesome thanks! I'll get this pulled in soon.
Return empty set early if no can rules are present.