### Question:
Utils { public static int hoursDiff(Date earlierDate, Date laterDate) { if (earlierDate == null || laterDate == null) { return 0; } int result = (int) ((laterDate.getTime() / ONE_HOUR_MILLIS) - (earlierDate.getTime() / ONE_HOUR_MILLIS)); return result >= 0 ? result : 0; } private  Utils(); static boolean isTestMode(); static String getUmaDiscoveryUrl(String p_amHost); static String joinAndUrlEncode(Collection<String> list); static String encode(String str); static String decode(String str); static int hoursDiff(Date earlierDate, Date laterDate); static long date(Date date); static String encodeCredentials(String username, String password); static boolean isValidUrl(String url); static boolean isTrue(Boolean bool); static List<String> stringToList(String source); static String mapAsStringWithEncodedValues(Map<String, String> p_map); static Date addTimeToDate(Date date, int timeValue, int timeFormat); static Properties loadPropertiesFromFile(String filename, Properties props);  }### Answer:
@Test public void hoursDiff() { Calendar calendar = Calendar.getInstance(); Date today = new Date(); calendar.add(Calendar.HOUR, 13); assertEquals(Utils.hoursDiff(today, calendar.getTime()), 13); }