using System;

using System.Collections;

using System.Collections.Generic;

using System.Linq;

using System.Text;

​

using Newtonsoft.Json;

using Newtonsoft.Json.Linq;

using Newtonsoft.Json.Converters;

using Newtonsoft.Json.Serialization;    

​

using ReflectionMagic;

​

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

​

//MCVE for:

//https://stackoverflow.com/questions/78995685/c-sharp-jsonconvert-serializeobject-is-updating-the-date

​

    class TestClass

    {

        public static void Test()

        {

            //TestInner();

            using (new FakeLocalTimeZone(TimeZoneInfo.FindSystemTimeZoneById("Etc/GMT+2")))

            {

                Assert.AreEqual("Etc/GMT+2", TimeZoneInfo.Local.Id);

                Assert.AreEqual(TimeSpan.FromHours(-2), TimeZoneInfo.Local.BaseUtcOffset);

                Console.WriteLine("Testing time zone {0}:", TimeZoneInfo.Local.Id);

                TestInner();

            }           

        }

        public static void TestInner()

        {

            var content = GetJson();

​

            var freeContent = JsonConvert.SerializeObject(JsonConvert.DeserializeObject(content));

            Console.WriteLine(content);

            Console.WriteLine(freeContent);

            var settings = new JsonSerializerSettings { DateParseHandling = DateParseHandling.None };

            Assert.That(JToken.DeepEquals(JsonConvert.DeserializeObject<JToken>(content, settings), JsonConvert.DeserializeObject<JToken>(freeContent, settings)));

        }

        static string GetJson() =>

"""

{

    "date": {

        "start": "2020-10-23T15:30:00+00:00"

    }

}

""";

    }

​

    // From this answer https://stackoverflow.com/a/63700512

    // By https://stackoverflow.com/users/21698/0xced

    // To https://stackoverflow.com/questions/44413407/mock-the-country-timezone-you-are-running-unit-test-from

    public class FakeLocalTimeZone : IDisposable

    {

        private readonly TimeZoneInfo _actualLocalTimeZoneInfo;

​

        private static void SetLocalTimeZone(TimeZoneInfo timeZoneInfo)

        {

            typeof(TimeZoneInfo).AsDynamicType().s_cachedData._localTimeZone = timeZoneInfo;

        }

​

        public FakeLocalTimeZone(TimeZoneInfo timeZoneInfo)

        {

            _actualLocalTimeZoneInfo = TimeZoneInfo.Local;

            SetLocalTimeZone(timeZoneInfo);

        }

​

        public void Dispose()

        {

            SetLocalTimeZone(_actualLocalTimeZoneInfo);

        }

    }

​

    public class Program

    {

        public static void Main()

        {

            Console.WriteLine("Environment version: {0} ({1}), {2}", System.Runtime.InteropServices.RuntimeInformation.FrameworkDescription , Environment.Version, Environment.OSVersion);

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

            Console.WriteLine();

​

            try

            {

                TestClass.Test();

            }

            catch (Exception ex)

            {

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

                Console.WriteLine(ex);

                throw;

            }

        }

    }

​