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