public void AnyProductsShouldReturnTrueWhenThereAreProducts()
        {
            var options = new DbContextOptionsBuilder <ApplicationDbContext>()
                          .UseInMemoryDatabase(databaseName: $"CartService")
                          .Options;
            var dbContext = new ApplicationDbContext(options);

            var user = new User {
                UserName = "******", Cart = new Cart()
            };

            dbContext.Users.Add(user);

            var product = new Product {
                Name = "USB Cable"
            };

            dbContext.Products.Add(product);
            dbContext.SaveChanges();

            var userService = new Mock <IUsersService>();

            userService.Setup(r => r.GetUserByUsername(user.UserName))
            .Returns(user);

            var productService = new Mock <IProductsSerivce>();

            productService.Setup(p => p.GetProductById(product.Id))
            .Returns(product);

            var cartsService = new CartService(dbContext, productService.Object, userService.Object);

            cartsService.AddProductToCart(product.Id, user.UserName);

            var areThereAnyProducts = cartsService.AnyProducts(user.UserName);

            Assert.True(areThereAnyProducts);
        }