using System;

using System.Text;

using System.Text.Json;

using System.Text.Json.Serialization;

​

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

​

#nullable enable

​

//https://stackoverflow.com/questions/78347638/jsonconverterattribute-is-not-used-by-jsonserializer

// Also see the MCVE here: https://dotnetfiddle.net/hAbHN6

​

​

namespace TestJsonConverterBug

{

    internal class Program

    {

        static readonly JsonSerializerOptions _options = new();

​

        static void Main()

        {

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

            Console.WriteLine("System.Text.Json version: " + typeof(JsonSerializer).Assembly.FullName);

            Console.WriteLine();

​

            _options.Converters.Add(new JsonEncodingConverter());

​

            TestOptions();

            TestAttributeSerialize();

            TestAttributeDeserialize();

        }

        // WORKS WITH OPTIONS

        static void TestOptions()

        {

            var obj = new SerializableClass1();

​

            var json = JsonSerializer.Serialize(obj, _options);

​

            var enc = JsonSerializer.Deserialize<SerializableClass1>(json, _options);

​

            Console.WriteLine("TestOptions(): {0} round-tripped successfully with JSON {1}.\n", enc, json);

​

            Assert.That(obj.Encoding == enc?.Encoding);

        }

​

        // DOESN'T WORK WITH CONVERTER ATTRIBUTE

        static void TestAttributeSerialize()

        {

            var obj = new SerializableClass2();

​

            var json = JsonSerializer.Serialize(obj);

​

            Console.WriteLine("TestAttributeSerialize(): {0} serialized successfully with JSON {1}.\n", obj, json);

        }

​

        // DOESN'T WORK WITH CONVERTER ATTRIBUTE

        static void TestAttributeDeserialize()

        {

            var obj = new SerializableClass2();

​

            var json = JsonSerializer.Serialize(obj, _options);

​

            var enc = JsonSerializer.Deserialize<SerializableClass2>(json);

​

            Console.WriteLine("TestOptions(): {0} round-tripped successfully with JSON {1}.\n", enc, json);

            Assert.That(obj.Encoding == enc?.Encoding);

        }

    }

​

    internal class SerializableClass1

    {

        public SerializableClass1()

        {

            Encoding = Encoding.ASCII;

        }

​

        public Encoding Encoding { get; set; }

    }

​

    internal class SerializableClass2

    {

        public SerializableClass2()

        {

            Encoding = Encoding.ASCII;

        }

​

        [JsonInclude, JsonPropertyName("Encoding")]

        string EncodingName { get => Encoding?.EncodingName!; set => Encoding = Encoding.GetEncoding(value); }

​

        [JsonIgnore]

        public Encoding Encoding { get; set; }

    }

​

    internal class JsonEncodingConverter : JsonConverter<Encoding>

    {

        public override bool CanConvert(Type typeToConvert)

            => typeToConvert.IsAssignableTo(typeof(Encoding));

​

        public override Encoding? Read(

            ref Utf8JsonReader reader,

            Type typeToConvert,

            JsonSerializerOptions options

        ) => Encoding.GetEncoding(reader.GetString()!);

​

        public override void Write(

            Utf8JsonWriter writer,

            Encoding value,

            JsonSerializerOptions options

        ) => writer.WriteStringValue(value.EncodingName);

    }

}

​