roadie/Roadie.Api.Library/Extensions/TimeSpanExt.cs

using System;

namespace Roadie.Library.Extensions
{
    public static class TimeSpanExt
    {
        public static string ToDuration(this TimeSpan input)
        {
            if (input == default || input.TotalMilliseconds == 0)
            {
                return "--/--/--";
            }

            return input.ToString(@"ddd\.hh\:mm\:ss");
        }
    }
}