Added unit tests for backend transtions.

app/models/translation.rb

@@ -1,6 +1,19 @@
 class Translation < ApplicationModel
   before_create :set_initial
 
+  def self.translate(locale, string)
+
+    # translate string
+    record = Translation.where( :locale => locale, :source => string ).first
+    return record.target if record
+
+    # fallback lookup in en
+    record = Translation.where( :locale => 'en', :source => string ).first
+    return record.target if record
+
+    return string
+  end
+
   private
     def set_initial
       self.target_initial = self.target

test/unit/translation_test.rb

@@ -0,0 +1,34 @@
+# encoding: utf-8
+require 'test_helper'
+ 
+class TranslationTest < ActiveSupport::TestCase
+  test 'translation' do
+    tests = [
+
+      # test 1
+      {
+        :lang   => 'en',
+        :string => 'New',
+        :result => 'New',
+      },
+
+      # test 2
+      {
+        :lang   => 'de',
+        :string => 'New',
+        :result => 'Neu',
+      },
+
+      # test 3
+      {
+        :lang   => 'de',
+        :string => 'not translated - lalala',
+        :result => 'not translated - lalala',
+      },
+    ]
+    tests.each { |test|
+      result = Translation.translate( test[:lang], test[:string] )
+      assert_equal( result, test[:result], "verify result" )
+    }
+  end
+end