using System;

public class Program

{

    public static void Main(string[] args)

    {

        Console.WriteLine("Starting OrderProcessingService Override Test");

        Console.WriteLine("\n");

        OrderProcessingService orderProcessingService = new OrderProcessingService();

        int number = orderProcessingService.MoveShoppingCartItemsToOrderItems();        

        Console.WriteLine("Trying to call override OrderProcessingService");

        Console.WriteLine("Number = {0}", number);

        Console.WriteLine("Should have printed : Number = 2");

        Console.WriteLine("\n");

​

        CustomOrderProcessingService customorderProcessingService = new CustomOrderProcessingService();

        number = customorderProcessingService.MoveShoppingCartItemsToOrderItems();  

        Console.WriteLine("Calling override function directly");

        Console.WriteLine("Number = {0}", number);

        Console.WriteLine("Should have printed : Number = 2");

    }

    public partial interface IOrderProcessingService

    {

        public int MoveShoppingCartItemsToOrderItems();

    }

​

    public partial class OrderProcessingService : IOrderProcessingService

    {

        Functions function = new Functions();

​

        public virtual int MoveShoppingCartItemsToOrderItems()

        {

            return function.Get(1);

        }

    }

    public class CustomOrderProcessingService : OrderProcessingService

    {

        Functions function = new Functions();

​

        public override int MoveShoppingCartItemsToOrderItems()

        {

            return function.Get(2);

        }

    }

​

    public class Functions

    {

        public int Get(int number)

        {

            return number;

        }

    }

}

​