public void UpdateCar_CanUpdate() {
            // Arrange
            var car = new Car {
                Id = 1,
                User = _currentUser,
                Make = "DCM-12",
                Model = "DeLorean",
                NumberPlate = "OUTOFTIME"
            };
            _fakeApplicationDbContext.Cars.Add(car);

            var carService = new CarService(_fakeApplicationDbContext, _mockCurrentUserService.Object);

            var updatedCar = new Car {
                Id = 1,
                Make = "DeLorean",
                Model = "DMC-12",
                NumberPlate = "OUTATIME"
            };

            // Act
            car = carService.UpdateCar(updatedCar);

            // Assert
            Assert.IsNotNull(updatedCar);
            Assert.AreEqual(car.Make, "DeLorean");
            Assert.AreEqual(car.Model, "DMC-12");
            Assert.AreEqual(car.NumberPlate, "OUTATIME");
        }