public void RuleCustomersCannotHaveMoreThanFiveOrdersAMonth_CustomerHasAlreadyPlacedThreeOrders_Valid() { //Arrange var order = new Order { OrderId = null, CustomerId = 2, OrderDateTime = DateTime.Today }; //Act var res = _orderValidation.RuleCustomersCannotHaveMoreThanFiveOrdersAMonth().Validate(order); //Assert Assert.IsTrue(res.IsValid); }