public void IncrementProductQuantityInBasket_GivenProductExistsInBasket_ShouldIncrementProductQuantity()
        {
            // Arrange
            InMemoryProductDbContext ctx = CreateTestDatabase();
            BasketRepository         basketRepository = new BasketRepository(ctx);

            // Act
            List <Product> productsToAdd = new List <Product>()
            {
                new Product()
                {
                    Title = "Product 1"
                },
                new Product()
                {
                    Title = "Product 2"
                }
            };

            foreach (var product in productsToAdd)
            {
                ctx.Products.Add(product);
            }
            ctx.SaveChanges();

            // Add new basket to database
            string ownerId = "george";

            basketRepository.CreateBasket(ownerId);

            // Add products to basket
            Basket basket = basketRepository.GetBasketByOwnerId(ownerId);

            foreach (var product in productsToAdd)
            {
                basketRepository.AddProductToBasket(product.ProductId, basket.OwnerID);
            }

            basketRepository.IncrementProductQuantityInBasket(2, ownerId);
            basket = basketRepository.GetBasketByOwnerId(ownerId);

            // Assert
            Assert.AreEqual(1, basket.BasketItems[0].ProductQuantity);
            Assert.AreEqual(2, basket.BasketItems[1].ProductQuantity);
        }