How to use stringBuilderWriter

//In folder IO
using System;
using System.Collections.Generic;
using System.IO;
using System.Text;
using WarCroft.Core.IO.Contracts;

namespace WarCroft.Core.IO
{
    public class StringBuilderWriter : IWriter
    {
        public StringBuilder sb = new StringBuilder();

        public void WriteLine(string message)
        {
            sb.AppendLine(message);
        }
    }
}


// in StartUp

using System;
using WarCroft.Core;
using WarCroft.Core.IO;
using WarCroft.Core.IO.Contracts;

namespace WarCroft
{
    public class StartUp
    {
        public static void Main(string[] args)
        {
           // IReader reader = new ConsoleReader();
           // IWriter writer = new ConsoleWriter();

           // var engine = new Engine(reader, writer);
          //  engine.Run();

                /* Use the below configuration instead of the usual one if you wish to print all output messages together after the inputs for easier comparison with the example output. */

            IReader reader = new ConsoleReader();
            var sbWriter = new StringBuilderWriter();

            var engine = new Engine(reader, sbWriter);
            engine.Run();
            Console.WriteLine(sbWriter.sb.ToString().Trim());
        }
    }
}