Added check to not save an update action unless model is changed

lib/public_activity/actions/update.rb

@@ -11,7 +11,7 @@ module Update
 
     # Creates activity upon modification of the tracked model
     def activity_on_update
-      create_activity(:update)
+      create_activity(:update) if changed?
     end
   end
 end

test/test_common.rb

@@ -48,6 +48,16 @@
     subject.create_activity("some.key").wont_be_nil
   end
 
+  it 'update action should not create activity on save unless model changed' do
+    subject.save
+    before_count = subject.activities.count
+    subject.save
+    subject.save
+    after_count = subject.activities.count
+    before_count.must_equal after_count
+  end
+
+
   it 'allows passing owner through #create_activity' do
     article = article().new
     article.save

test/test_tracking.rb

@@ -154,6 +154,7 @@ class ActivistAndTrackedArticle < ActiveRecord::Base
       PublicActivity::Activity.count.must_equal activity_count_before
 
       klass.public_activity_on
+      @article.name = 'Changed Article'
       @article.save
       PublicActivity::Activity.count.must_be :>, activity_count_before
     end