### Question:
DateUtils { @VisibleForTesting static boolean isThreeLetterTZName(String tzId) { Matcher m = THREE_LETTER_ID_PATTERN.matcher(tzId); return m.matches() && !tzId.equalsIgnoreCase("UTC") && !tzId.equalsIgnoreCase("GMT"); }  static void setConf(Configuration conf); static TimeZone getOozieProcessingTimeZone(); static String getOozieTimeMask(); static TimeZone getTimeZone(String tzId); static Date parseDateUTC(String s); static Date parseDateOozieTZ(String s); static String formatDateOozieTZ(Date d); static String formatDateCustom(Date d, String format); static String formatDateEpoch(Date d, Boolean millis); static String formatDateOozieTZ(Calendar c); static String formatDate(Calendar c); static int hoursInDay(Calendar cal); static boolean isDSTChangeDay(Calendar cal); static void moveToEnd(Calendar cal, TimeUnit endOfFlag); static Calendar getCalendar(String dateString, TimeZone tz); static Calendar getCalendar(String dateString); static java.util.Date toDate(java.sql.Timestamp timestamp); static Timestamp convertDateToTimestamp(Date d); static final TimeZone UTC; static final String ISO8601_UTC_MASK; static final String OOZIE_PROCESSING_TIMEZONE_KEY; static final String OOZIE_PROCESSING_TIMEZONE_DEFAULT; }### Answer:
@Test public void testIsThreeLetterTZName() { Assert.assertTrue(DateUtils.isThreeLetterTZName("PST")); Assert.assertTrue(DateUtils.isThreeLetterTZName("PDT")); Assert.assertTrue(DateUtils.isThreeLetterTZName("BST")); Assert.assertTrue(DateUtils.isThreeLetterTZName("CST")); Assert.assertFalse(DateUtils.isThreeLetterTZName("UTC")); Assert.assertFalse(DateUtils.isThreeLetterTZName("GMT")); Assert.assertFalse(DateUtils.isThreeLetterTZName("America/Los_Angeles")); }