using System;

using System.Collections;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Runtime.Serialization.Formatters;

using System.IO;

using System.Data;

using System.ComponentModel.DataAnnotations;

using System.Globalization;

using System.Reflection;

using System.Collections.ObjectModel;

using System.Runtime.Serialization.Json;

using System.Runtime.Serialization;

​

using Newtonsoft.Json;

using Newtonsoft.Json.Linq;

using Newtonsoft.Json.Converters;

using Newtonsoft.Json.Serialization;    

​

using NUnit.Framework; // Throws NUnit.Framework.AssertionException

​

//https://stackoverflow.com/questions/62634032/datacontractjsonserializer-and-jsonconvert-serailization-of-datetimeoffset-produ

​

    [DataContract]

    public class TestToSeailize

    {

        [DataMember]

        public DateTimeOffset SaveDate { get; set; }

    }

​

    class TestClass

    {

        public static void Test()

        {

            var settings = new DataContractJsonSerializerSettings

            {

                DateTimeFormat = new DateTimeFormat("yyyy-MM-ddTHH\\:mm\\:ss.ffFFFFFzzz", CultureInfo.InvariantCulture)

                {

                },

            };

            TestDataContractJsonSerializer(null);

            TestDataContractJsonSerializer(settings);

            TestJsonNet();

        }   

        static string TestDataContractJsonSerializer(DataContractJsonSerializerSettings settings)

        {

            TestToSeailize item = new TestToSeailize()

            {

                SaveDate = new DateTimeOffset(2020 , 06, 05 , 3 ,0, 0,  TimeSpan.FromHours(5))

            };

​

            DataContractJsonSerializer serializer = new DataContractJsonSerializer(item.GetType(), settings);

            using (MemoryStream ms = new MemoryStream())

            {

                serializer.WriteObject(ms, item);

                var json = Encoding.UTF8.GetString(ms.ToArray()); 

                Console.WriteLine(json);

                return json;

            }

        }

​

        static string TestJsonNet()

        {

            TestToSeailize item = new TestToSeailize()

            {

                SaveDate = new DateTimeOffset(2020, 06, 05, 3, 0, 0, TimeSpan.FromHours(5))

            };

​

            string json = JsonConvert.SerializeObject(item);

​

            Console.WriteLine(json);

            return json;

        }

    }

​

    public class Program

    {

        public static void Main()

        {

            Console.WriteLine("Environment version: {0} ({1})", System.Runtime.InteropServices.RuntimeInformation.FrameworkDescription , GetNetCoreVersion());

            Console.WriteLine("{0} version: {1}", typeof(JsonSerializer).Assembly.GetName().Name,  typeof(JsonSerializer).Assembly.FullName);

            Console.WriteLine();

​

            try

            {

                TestClass.Test();

            }

            catch (Exception ex)

            {

                Console.WriteLine("Failed with unhandled exception: ");

                Console.WriteLine(ex);

                throw;

            }

        }

        public static string GetNetCoreVersion()

        {

            //https://techblog.dorogin.com/how-to-detect-net-core-version-in-runtime-ecd65ad695be

            //

            var assembly = typeof(System.Runtime.GCSettings).GetTypeInfo().Assembly;

            var assemblyPath = assembly.CodeBase.Split(new[] { '/', '\\' }, StringSplitOptions.RemoveEmptyEntries);

            int netCoreAppIndex = Array.IndexOf(assemblyPath, "Microsoft.NETCore.App");

            if (netCoreAppIndex > 0 && netCoreAppIndex < assemblyPath.Length - 2)

                return assemblyPath[netCoreAppIndex + 1];

            return null;

        }

    }

​