@Test
public void testToString() {

    // when
    model.id = PROVINCE_ID;
    model.name = PROVINCE_NAME;
    // then
    assertEquals("ProvinceName[ProvinceId][0 cities]", model.toString());
    // when
    model.addCity(new CityModel());
    // then
    assertEquals("ProvinceName[ProvinceId][1 cities]", model.toString());
    // when
    for (CityModel city : cities) {
        model.addCity(city);
    }
    // then
    assertEquals("ProvinceName[ProvinceId][" + (CITIES_NUM + 1) + " cities]", model.toString());
}