@Override
    public Set<City> findAllByCountry(Country country) {
        return cityRepository.findAllByCountry(country);
    }
@Test
    void findAllByCountry() {
        City city = createCity();
        Country country = city.getCanton().getCountry();
        Mockito.when(cityRepository.findAllByCountry(country))
                .thenReturn(Collections.singleton(city));
        Set<City> expected = Set.of(city);
        Set<City> actual = cityService.findAllByCountry(country);
        ReflectionAssert.assertReflectionEquals(expected, actual);
    }