This should pass, right? http://ayende.com/wiki/RecursiveMocksGuidance.ashx - but it fails

RhinoMocksRecursiveMocking.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Rhino.Mocks;
using Xunit;

namespace ClassLibrary1
{
    public class RhinoMocksRecursiveMocking
    {
        [Fact]
        public void RecursiveMocksTesting()
        {
            var complicatedSUT = MockRepository.GenerateStub<IFirstDep>();

            Assert.Equal(complicatedSUT.SecondDep.Name, string.Empty);
        }
    }
    public interface IFirstDep
    {
        ISecondDep SecondDep { get; set; }
    }
    public interface ISecondDep
    {
        string Name { get; set; }
    }
}