public void testToLocalDate() {
        MonthDay base = new MonthDay(6, 6, COPTIC_UTC);
        LocalDate test = base.toLocalDate(2009);
        assertEquals(new LocalDate(2009, 6, 6, COPTIC_UTC), test);
        try {
            base.toLocalDate(0);
            fail();
        } catch (IllegalArgumentException ex) {}
    }