Raise exception when date.order includes invalid elements

actionpack/lib/action_view/helpers/date_helper.rb

@@ -836,7 +836,15 @@ def date_order
         end
 
         def translated_date_order
-          I18n.translate(:'date.order', :locale => @options[:locale]) || []
+          date_order = I18n.translate(:'date.order', :locale => @options[:locale]) || []
+
+          forbidden_elements = date_order - [:year, :month, :day]
+          if forbidden_elements.any?
+            raise StandardError,
+              "#{@options[:locale]}.date.order only accepts :year, :month and :day"
+          end
+
+          date_order
         end
 
         # Build full select tag from date type and options.

actionpack/test/template/date_helper_i18n_test.rb

@@ -118,4 +118,12 @@ def test_date_or_time_select_given_no_order_options_translates_order
     I18n.expects(:translate).with(:'date.order', :locale => 'en').returns [:year, :month, :day]
     datetime_select('post', 'updated_at', :locale => 'en')
   end
+
+  def test_date_or_time_select_given_invalid_order
+    I18n.expects(:translate).with(:'date.order', :locale => 'en').returns [:invalid, :month, :day]
+
+    assert_raise StandardError do
+      datetime_select('post', 'updated_at', :locale => 'en')
+    end
+  end
 end