public void CanUpdateExistingProduct()
        {
            if (_products != null)
            {
                var product = _products[0];
                product.Name = "TestProductRename";
                product.Description = "TestProductDescriptionChange";
                product.Price = 99;

                IProductRepository repository = new ProductRepository();
                repository.Update(product);

                // use session to try to load the product
                using (ISession session = _sessionFactory.OpenSession())
                {
                    var fromDb = session.Get<Product>(product.ProductId);
                    Assert.AreEqual(product.Name, fromDb.Name);
                    Assert.AreEqual(product.Description, fromDb.Description);
                    Assert.AreEqual(product.Price, fromDb.Price);
                }
            }
        }