EntityFramework Change Tracking

db_context

public class Db : DbContext
{
    public Db() : base("Db")
    {
        Configuration.LazyLoadingEnabled = true;
    }

    public DbSet<Foo> Foos { get; set; }
    public DbSet<Bar> Bars { get; set; }
}

db_initializer

public class DbInitializer : DropCreateDatabaseAlways<Db>
{
    protected override void Seed(Db context)
    {
        context.Foos.Add(new Foo
        {
            Value = "Value", 
            Bars = new List<Bar>
            {
                new Bar { Value = "Value" }
            }
        });

        context.SaveChanges();
    }
}

entities

public class Foo
{
    public int Id { get; set; }
    public string Value { get; set; }
    public virtual ICollection<Bar> Bars { get; set; }
}

public class Bar
{
    public int Id { get; set; }
    public string Value { get; set; }

    public int FooId { get; set; }
    public virtual Foo Foo { get; set; }
}

test

[TestFixture]
public class Test
{
    [Test]
    public void TestChangeTracking()
    {
        System.Data.Entity.Database.SetInitializer(new DbInitializer());
        
        Foo foo;
        // Read and send to the client over the wire
        using (var db = new Db())
        {
            foo = db.Foos.First();
            Assert.AreEqual(1, foo.Bars.Count);
        }

        // Client changes some values
        foo.Value = "Changed";
        foo.Bars.First().Value = "Changed";

        // Post to server for an update
        using (var db = new Db())
        {
            db.Foos.AddOrUpdate(foo);
            db.SaveChanges();
        }

        // What got saved?
        using (var db = new Db())
        {
            foo = db.Foos.First();
            Console.WriteLine("Foo.Value: {0}", foo.Value);
            Console.WriteLine("Foo.Bars[0].Value: {0}", foo.Bars.First().Value);
        }

        Assert.Fail("Use nhibernate instead.");
    }
}