public void TestItAll()
        {
            List <Car> cars = _manager.GetAll();

            Assert.AreEqual(3, cars.Count);

            cars = _manager.GetAll(vendor: "V");
            Assert.AreEqual(1, cars.Count);

            cars = _manager.GetAll(minPrice: 20);
            Assert.AreEqual(2, cars.Count);

            cars = _manager.GetAll(minPrice: 21);
            Assert.AreEqual(1, cars.Count);

            cars = _manager.GetAll(maxPrice: 20);
            Assert.AreEqual(2, cars.Count);

            cars = _manager.GetAll(maxPrice: 18);
            Assert.AreEqual(1, cars.Count);

            Car car = _manager.GetById(1);

            Assert.AreEqual(1, car.Id);

            Assert.IsNull(_manager.GetById(100));

            int howMany = _manager.GetAll().Count;
            Car newCar  = new Car {
                Make = "WV", Model = "Polo", Price = 25
            };
            Car c = _manager.Add(newCar);

            Assert.AreEqual(howMany + 1, _manager.GetAll().Count);

            Car updatedCar = _manager.Update(c.Id, new Car()
            {
                Make = "WV", Model = "Polo", Price = 26
            });

            Assert.AreEqual(26, updatedCar.Price);

            Assert.IsNull(_manager.Update(100, null));

            howMany = _manager.GetAll().Count;
            Car deletedCar = _manager.Delete(1);

            Assert.AreEqual(1, deletedCar.Id);

            Assert.IsNull(_manager.Delete(100));
        }
        public ActionResult <Car> Get(int id)
        {
            Car car = _manager.GetById(id);

            if (car == null)
            {
                return(NotFound("No such id: " + id));
            }
            return(car);
        }