Ugly attempt at mocking out static class

gistfile1.cs

using System;
using Microsoft.VisualStudio.TestTools.UnitTesting;
using Moq;

namespace UnitTestStatic
{
    public class Utilities : IUtilities
    {
        private static IUtilities _instance = new Utilities();
        private Utilities() { }
        public static IUtilities Instance
        {
            get { return _instance; }
        }

        public static string Method1()
        {
            return Utilities.Instance.Method1();
        }

        string IUtilities.Method1()
        {
            return "a";
        }
    }

    public interface IUtilities
    {
        string Method1();
    }

    [TestClass]
    public class UnitTest1
    {
        [TestMethod]
        public void TestMethod1()
        {
            IUtilities unused = Utilities.Instance;

            System.Reflection.FieldInfo instance = typeof(Utilities).GetField("_instance", System.Reflection.BindingFlags.Static | System.Reflection.BindingFlags.NonPublic);

            var mock = new Mock<IUtilities>();
            mock.Setup(item => item.Method1()).Returns("b");
            instance.SetValue(null, mock.Object);


            string ret = Utilities.Method1();
            StringAssert.StartsWith(ret, "b");

        }
    }
}

#38 is only needed if you instantiate instance on demand vs create it initially like I did (too lazy to update example right now)