@Test(expectedExceptions = CalendricalException.class)
 public void testMinusYearsInvalidTooSmall() {
   testDate.minusYears(20000);
 }
 // -----------------------------------------------------------------------
 // minusYears()
 // -----------------------------------------------------------------------
 @Test
 public void testMinusYears() {
   assertEquals(
       testDate.minusYears(10), MinguoDate.of(testYear - 10, testMonthOfYear, testDayOfMonth));
 }