public void testPlus_int() {
        Months test2 = Months.months(2);
        Months result = test2.plus(3);
        assertEquals(2, test2.getMonths());
        assertEquals(5, result.getMonths());
        
        assertEquals(1, Months.ONE.plus(0).getMonths());
        
        try {
            Months.MAX_VALUE.plus(1);
            fail();
        } catch (ArithmeticException ex) {
            // expected
        }
    }