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);
}