+      interface "ActiveModel" do
+        Boolean = [TrueClass, FalseClass]
+        method :valid? => "Boolean"
+        method :new_record? => "Boolean"
+        method :destroyed? => "Boolean"
+        method :errors => "Errors"
+      end
+      
+      enum "Boolean", true, false      
+      
+      interface "Errors" do
+        method :[] => Array, :args => [Symbol]
+        method :full_messages => Array
+      end
+      
+      test_interface "Errors#[]", :with => [:hello]
+