Using ActiveRecord / NHibernate, can I uninstall and update without flashing?

I have the following Unit Test method:

void TestOrderItemDelete()
{
    using (new SessionScope())
    {
        var order = Order.FindById(1234);
        var originalItemCount = order.OrderItems.Count;
        Assert.IsTrue(originalCount > 0);
        var itemToDelete = order.OrderItems[0];
        itemToDelete.DeleteAndFlush(); // itemToDelete.Delete();
        order.Refresh();
        Assert.AreEqual(originalCount - 1, order.OrderItems.Count);
    }
}

      

        
        
        
      

    

As you can see from the comment after the DeleteAndFlush command, I had to change it from a simple Delete to pass the Unit Test. Why is this? The same does not apply to my other Unit Test for adding OrderItem. This works great:

void TestOrderItemAdd()
{
    using (new SessionScope())
    {
        var order = Order.FindById(1234);
        var originalItemCount = order.OrderItems.Count;
        var itemToAdd = new OrderItem();
        itemToAdd.Order = order;
        itemToAdd.Create(); // Notice, this is not CreateAndFlush
        order.Refresh();
        Assert.AreEqual(originalCount + 1, order.OrderItems.Count);
    }
}

      

        
        
        
      

    

This all happened when I started using Lazy Instantiation to map Order.OrderItems relationships and had to add a use block (new SessionScope) around the test.

Any ideas?