public void test_compareTo() {
        assertEquals(0, MillisDurationField.INSTANCE.compareTo(MillisDurationField.INSTANCE));
        assertEquals(-1, MillisDurationField.INSTANCE.compareTo(ISOChronology.getInstance().seconds()));
        DurationField dummy = new PreciseDurationField(DurationFieldType.seconds(), 0);
        assertEquals(1, MillisDurationField.INSTANCE.compareTo(dummy));
//        try {
//            MillisDurationField.INSTANCE.compareTo("");
//            fail();
//        } catch (ClassCastException ex) {}
        try {
            MillisDurationField.INSTANCE.compareTo(null);
            fail();
        } catch (NullPointerException ex) {}
    }