Loop referencing exceptions only with .Net Core 2.2

[Anthony-Breneliere]

I have got a loop referencing exception with .Net Core 2.2 but not Framework .NET 4.72, when serializing mocked objects with moq. Shouldn't the behavior be the same ? Here is the code to reproduce the exception:

using Moq;
using System;
using System.Runtime.Serialization;

namespace ConsoleApp1
{
    public interface IAction
    {
        string Description { get; }
        object Argument { get; }
    }

    class Program
    {
        static void Main(string[] args)
        {
            var actionMock = new Mock<IAction>().SetupAllProperties();
            // actionMock.As<ISerializable>();
            Console.WriteLine(Newtonsoft.Json.JsonConvert.SerializeObject(actionMock.Object));
        }
    }
}

Result: Newtonsoft.Json.JsonSerializationException: 'Self referencing loop detected for property 'Object' with type 'Castle.Proxies.IActionProxy'. Path 'Mock'.'

With .Net Framework the object actionMock.Object is properly serialized.

Moq is 4.10.1 and Newtonsoft.Json 12.0.2

[dbc2]

Json.NET's implementation of self-referencing loop detection depends on the object.Equals() implementations of the underlying objects. For details see:

• Why doesn't reference loop detection use reference equality?.
• Issue #401: Object reference equality should be used when checking for circular references

If the implementations of object.Equals() for mocked objects differ between .Net Core 2.2 and .NET Framework 4.72, you'll get different results for reference loop detection.

Using your own equality comparer on both frameworks, e.g. ObjectReferenceEqualityComparer<object> from IEqualityComparer<T> that uses ReferenceEquals, may make the two frameworks behave consistently.

Also, did you see How to mock (with Moq) an interface that is serialized by Newtonsoft.json?? The error looks to be identical.