private static void AddDummyOrders(this CrUDOnlyDbContext context, List <Book> books = null) { if (books == null) { books = context.Books.ToList(); } var orders = new List <Order>(); var i = 0; foreach (var usersId in DummyUsersIds) { orders.Add(BuildDummyOrder(usersId, DateTime.UtcNow.AddDays(-10), books[i++])); orders.Add(BuildDummyOrder(usersId, DateTime.UtcNow, books[i++])); } context.AddRange(orders); }