using LiteDB;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Xunit;

namespace LiteDB.Tests;

public class LiteDB_Bug
{
    [Fact]
    public void CovariantCollectionIsMissingTypeInfo()
    {
        IA a = new A { Bs = new List<B> { new B() } };

        var docA = BsonMapper.Global.Serialize<IA>(a).AsDocument;
        var docB = docA["Bs"].AsArray[0].AsDocument;

        Assert.True(docA.ContainsKey("_type")); // OK
        Assert.True(docB.ContainsKey("_type")); // KO
    }

    interface IA
    {
        // at runtime this will be a List<B>
        IReadOnlyCollection<IB> Bs { get; set; }
    }

    class A : IA
    {
        public IReadOnlyCollection<IB> Bs { get; set; }
    }

    interface IB { }
    class B : IB { }
}