public void ItemService_NullStrings_NullException()
        {
            //arrange
            var         dataConverter      = new Mock <IDataConverter>();
            var         dataManager        = new Mock <IItemManager>();
            var         itemCategorization = new Mock <IItemCategorization>();
            ItemService itemService        = new ItemService(dataConverter.Object, dataManager.Object, itemCategorization.Object);

            //act

            //assert
            Assert.Throws <NullReferenceException>(() => itemService.AddChangeCategory(null, null));
        }