public void ShouldDecreaseTwiceAsFastIfSellByIsPast()
        {
            // arrange
            Item item = new CommonItem(18, 0, string.Empty);

            // act
            item.Process();

            // assert
            item.GetQuality.Should().Be(16);
        }
        public void ShouldDegradeInQuality()
        {
            // arrange
            Item item = new CommonItem(10, 9, string.Empty);

            // act
            item.Process();

            // assert
            item.GetQuality.Should().Be(9);
        }
        public void ShouldDecreaseSellBy()
        {
            // arrange
            Item item = new CommonItem(18, 10, string.Empty);

            // act
            item.Process();

            // assert
            item.GetSellBy.Should().Be(9);
        }