Take a look here: https://github.com/comfy/comfortable-mexican-sofa/wiki/Docs:-CMS-Seeds#using-cms-seeds-in-tests
Also, depending on how you structure your tests, you can hit the fixture importer directly:
ComfortableMexicanSofa::Fixture::Importer.new(from, to, :force).import!
Where from
is the folder name and to
is the identifier of the site.
Rake task works pretty good as it loads cms content only once for the duration of the entire test run. Also it doesn't get triggered if you're running focused tests. At least when using TestUnit, I don't like RSpec personally.