Just a reminder that in Rails 4, ActiveSupport::TestCase will now subclass MiniTest::Spec. This means you will get all the benefits of Test::Unit style assertions with the flexibility of a spec syntax and added spec assertions. But why wait?

You can future-proof your Rails 3 tests and start using MiniTest::Spec now! No changes to existing code! No generators! Just install the minitest-spec-rails gem. This gem tricks ActiveSupport into subclassing MiniTest::Spec. So start reducing the barrier to upgrade to Rails 4 now!