@Test
 public void testMinusDaysOverflow() throws Exception {
   try {
     testDate.minusDays(Integer.MAX_VALUE);
     fail();
   } catch (IllegalCalendarFieldValueException ex) {
     assertEquals(ex.getRule(), MinguoChronology.yearOfEraRule());
   }
 }
 // -----------------------------------------------------------------------
 // minusDays()
 // -----------------------------------------------------------------------
 @Test
 public void testMinusDays() {
   assertEquals(
       testDate.minusDays(2), MinguoDate.of(testYear, testMonthOfYear, testDayOfMonth - 2));
 }