public void AddingTest()
        {
            Mock <IDataFiller> mockRepository = new Mock <IDataFiller>();

            mockRepository.Setup(x => x.Fill()).Returns(data);
            Repository repository = new Repository(mockRepository.Object);


            List <Burger> Burgers = new List <Burger>();
            Burger        Burger  = new Burger("Testowa", 12.34f, "test");

            Burgers.Add(Burger);
            Customer customer = new Customer("Ala", "kotowa", "Ola@as", "123456789");
            Employee employee = new Employee("Włodek");
            Order    order    = new Order(customer, Burgers, employee, 10);

            repository.AddCustomer(customer);
            repository.AddEmployee(employee);
            repository.AddOrder(order);
            repository.AddBurger(Burger);
            repository.AddOrderToArchive(order);

            List <Burger>   BurgersL  = (List <Burger>)repository.GetAllBurgers();
            List <Customer> customers = (List <Customer>)repository.GetAllCustomers();
            List <Employee> employees = (List <Employee>)repository.GetAllEmployees();
            List <Order>    orders    = (List <Order>)repository.GetAllOrders();

            BurgersL.Count.Should().Be(4, "because we added one item to three items in the collection");
            customers.Count.Should().Be(5, "because we added one item to four items in the collection");
            employees.Count.Should().Be(4, "because we added one item to three items in the collection");
            orders.Count.Should().Be(1, "because we added one item to zero items in the collection");

            Assert.IsTrue(BurgersL.Contains(Burger));
            Assert.IsTrue(customers.Contains(customer));
            Assert.IsTrue(employees.Contains(employee));
            Assert.IsTrue(orders.Contains(order));
        }