@Test
public void testCollapseTemperatures() {

    WeatherService service = new WeatherService(new WeatherRestfullApi());
    Stream<Location> locals = service.search("oporto");
    Stream<Integer> temps = locals
        .skip(1)
        .findFirst()
        .get()
        .getPast30daysWeather()
        .map(WeatherInfo::getTempC);
    temps = StreamUtil.collapse(temps);
    String res = temps
        .map(Object::toString)
        .collect(Collectors.joining(","));
    String expected = "16,13,14,12,11,14,19,16,18,15,14,17,21,19,14,17,19,21,22,20,22,23,21,24,25,21,20,18";
    assertEquals(expected, res);
}