Mailer subjects namespaced by model

test/support/model_tests_helper.rb

@@ -3,6 +3,15 @@ class ActiveSupport::TestCase
     ActionMailer::Base.deliveries = []
   end
 
+  def store_translations(locale, translations, &block)
+    begin
+      I18n.backend.store_translations locale, translations
+      yield
+    ensure
+      I18n.reload!
+    end
+  end
+
   # Helpers for creating new users
   #
   def generate_unique_email