public void WhenCatalogContainsItem_GetReturnsItem()
        {
            IMyCatalogItem mockItem        = Substitute.For <IMyCatalogItem>();
            MyItemCatalog  systemUnderTest = new MyItemCatalog(new Dictionary <string, IMyCatalogItem>()
            {
                { "SomeId", mockItem }
            });

            Assert.AreEqual(mockItem, systemUnderTest.GetItem("SomeId"));
        }
        public void WhenCatalogDoesNotContainItem_GetReturnsNull()
        {
            MyItemCatalog systemUnderTest = new MyItemCatalog(new Dictionary <string, IMyCatalogItem>());

            Assert.IsNull(systemUnderTest.GetItem("SomeId"));
        }