public void Can_Delete_Book() { int id = 3; Mock <IRepository <Order> > mock = new Mock <IRepository <Order> >(); mock.Setup(m => m.GetAll()).Returns(new List <Order> { new Order { Id = 1, Name = "Order1" }, new Order { Id = 2, Name = "Order2" }, new Order { Id = 3, Name = "Order3" }, }); //BookRepository repository = new BookRepository(); TestHelps repository = new TestHelps(); List <Order> orders = repository.DeleteOrder(mock.Object, id); Assert.AreEqual(2, orders.Count); }