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;

​

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/65347359/serialization-problem-in-a-custom-collection-with-a-private-list

​

    class ListCollection : List<int>

    {

    }

​

    [Serializable]

    class PrivateListCollection: ISerializable, IEnumerable<int>

    {

        public PrivateListCollection() { }

        public PrivateListCollection(IEnumerable<int> items) => list.AddRange(items);

        private List<int> list = new List<int>();

​

        public void Add(int value)

        {

            list.Add(value);

        }

​

        public void GetObjectData(SerializationInfo info, StreamingContext context)

        {

            info.AddValue("items", list);

        }

        public IEnumerator<int> GetEnumerator() => list.GetEnumerator();

        IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();

    }

​

    class TestClass

    {

        public static void Test()

        {

            var list1 = new ListCollection { 1, 2, 3 };

            var list2 = new PrivateListCollection();

            foreach (var item in list1)

                list2.Add(item);

            var settings = new JsonSerializerSettings { };

            var json1 = JsonConvert.SerializeObject(list1, settings);

            var json2 = JsonConvert.SerializeObject(list2, settings);

            Console.WriteLine(json2);

            Assert.AreEqual(json1, json2);

            var list22 = JsonConvert.DeserializeObject<PrivateListCollection>(json1, settings);

            var json22 = JsonConvert.SerializeObject(list22, settings);

            Assert.AreEqual(json2, json22);

        }   

    }

​

    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.Location.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;

        }

    }

​