public void AddOrMerge_ShouldAddNewItems()
        {
            CardItemCollection cardItemCollection = new CardItemCollection {
                new CardItem {
                    Name = "test 01"
                }
            };

            cardItemCollection.AddItem(new CardItem {
                Name = "test 02"
            });
            Assert.AreEqual(2, cardItemCollection.Count);
        }
        public void AddOrMerge_ShouldMergeExistingItem()
        {
            CardItemCollection cardItemCollection = new CardItemCollection {
                new CardItem {
                    Name = "test 01"
                }
            };
            CardItem existing = cardItemCollection.AddItem(new CardItem {
                Name = "test 01", Count = 2
            });

            Assert.AreEqual(1, cardItemCollection.Count);
            Assert.AreEqual(3, existing.Count);
        }