public void testIsLessThan() {
   assertEquals(false, Minutes.THREE.isLessThan(Minutes.TWO));
   assertEquals(false, Minutes.THREE.isLessThan(Minutes.THREE));
   assertEquals(true, Minutes.TWO.isLessThan(Minutes.THREE));
   assertEquals(false, Minutes.ONE.isLessThan(null));
   assertEquals(true, Minutes.minutes(-1).isLessThan(null));
 }
 // -----------------------------------------------------------------------
 public void testConstants() {
   assertEquals(0, Minutes.ZERO.getMinutes());
   assertEquals(1, Minutes.ONE.getMinutes());
   assertEquals(2, Minutes.TWO.getMinutes());
   assertEquals(3, Minutes.THREE.getMinutes());
   assertEquals(Integer.MAX_VALUE, Minutes.MAX_VALUE.getMinutes());
   assertEquals(Integer.MIN_VALUE, Minutes.MIN_VALUE.getMinutes());
 }