persistent test case.cs

public sealed class GetState { }
public sealed class Increment { }

public sealed class Changed { }

public class TestCaseActor : UntypedPersistentActor
{
    private int state = 0;
    public override string PersistenceId { get; } = "yolo";

    protected override void OnCommand(object message)
    {
        Active(message);
    }

    private void Active(object message)
    {
        message.Match()
            .With<Increment>(inc =>
            {
                if (state >= 3)
                    Context.Become(Freezed);
                else
                    Persist(new Changed(), UpdateState);
            })
            .With<GetState>(_ => Sender.Tell(state));
    }

    private void Freezed(object message)
    {
        message.Match()
            .With<GetState>(_ => Sender.Tell(state));
    }

    protected override void OnRecover(object message)
    {
        message.Match()
            .With<Changed>(UpdateState);
    }

    private void UpdateState(Changed e)
    {
        state ++;
    }
}

// exec

using (var system = ActorSystem.Create("failing-sys"))
{
    var pref = system.ActorOf(Props.Create<TestCaseActor>());

    pref.Tell(new Increment());
    pref.Tell(new Increment());
    pref.Tell(new Increment());
    pref.Tell(new Increment());
    pref.Tell(new Increment());

    var state = pref.Ask<int>(new GetState()).Result;

    Console.WriteLine("State is: {0}", state);

    Console.ReadLine();
}