public void changes_to_the_system_property_raise_the_property_changed_event()
        {
            var model = new MessageModel();
            var observer = model.CreateObserver();

            model.Process(new SetSystemMessageMessage("message"));
            Assert.True(observer.HasChanged(x => x.System));
        }
        public void changes_to_the_commentary_property_raise_the_property_changed_event()
        {
            var model = new MessageModel();
            var observer = model.CreateObserver();

            model.Process(new AddCommentaryMessage("commentary"));
            Assert.True(observer.HasChanged(x => x.Commentary));
        }