30DaysOfTDD_Day21_Part4

        [Test]
        public void WhenUserPlacesACorrectOrderThenAnOrderNumberShouldBeReturned()
        {
            //Arrange
            var shoppingCart = new ShoppingCart();
            var itemId = Guid.NewGuid();
            shoppingCart.Items.Add(new ShoppingCartItem { ItemId = itemId, Quantity = 1 });
            var customerId = Guid.NewGuid();
            var expectedOrderId = Guid.NewGuid(); 
            var orderFulfillmentSessionId = Guid.NewGuid();            
            var customer = new Customer { Id = customerId };

            Mock.Arrange(() => _orderDataService.Save(Arg.IsAny<Order>()))
                .Returns(expectedOrderId)
                .OccursOnce();
            Mock.Arrange(() => _customerService.GetCustomer(customerId)).Returns(customer).OccursOnce();
            Mock.Arrange(() => _orderFulfillmentService.OpenSession(Arg.IsAny<string>(), Arg.IsAny<string>()))
                .Returns(orderFulfillmentSessionId).OccursOnce();
            Mock.Arrange(() => _orderFulfillmentService.IsInInventory(orderFulfillmentSessionId, itemId, 1))
                .Returns(true).OccursOnce();
            Mock.Arrange(() =>
                _orderFulfillmentService.
                    PlaceOrder(orderFulfillmentSessionId, Arg.IsAny<IDictionary<Guid, int>>(), Arg.IsAny<string>()))
                .Returns(true);
            Mock.Arrange(() => _orderFulfillmentService.CloseSession(orderFulfillmentSessionId)).OccursOnce();
            //Act
            var result = _orderService.PlaceOrder(customerId, shoppingCart);

            //Assert
            Assert.AreEqual(expectedOrderId, result);
            Mock.Assert(_orderDataService);
            Mock.Assert(_orderFulfillmentService);
        }