### Question:
Dates { public static Date fromMac(long seconds) { if (seconds == 0) { return null; } seconds &= 0xFFFFFFFFL; Calendar cal = Calendar.getInstance(); cal.setTimeZone(TimeZone.getTimeZone("Europe/London")); cal.clear(); cal.set(Calendar.YEAR, 1904); cal.set(Calendar.MONTH, 0); cal.set(Calendar.DATE, 1); long epoch = cal.getTimeInMillis() - 60 * 60 * 1000L; return new Date((seconds * 1000L) + epoch); }  static Date fromMac(long seconds);  }### Answer:
@Test public void zeroBecomesNullDate() { int a = 0; Date d = Dates.fromMac(a); assertNull(d); }