    @Test
    public void test() {

        Specification spec = new Specification();
        Car car = new Car(spec);

        when(entityManager.merge(any())).then(a -> a.getArgument(0));
        when(carFactory.createCar(any())).thenReturn(car);

        assertThat(testObject.manufactureCar(spec)).isEqualTo(car);

        verify(carFactory).createCar(spec);
        verify(entityManager).merge(car);
    }