public void AddOrderTest()
        {
            Good     book      = new Good(1, "book", 9.9f);
            Customer customer4 = new Customer(4, "jams");
            Order    order4    = new Order(4, customer4);

            order4.AddPurchase(new Purchase(book, 1));
            ordersTable.AddOrder(order4);
            List <Order> allOrders = ordersTable.QueryAll();

            Assert.AreEqual(1, allOrders.Count);
            CollectionAssert.Contains(allOrders, order4);
        }