public void testParseInto_simple() {
        MutablePeriod expect = new MutablePeriod(1, 2, 3, 4, 5, 6, 7, 8);
        MutablePeriod result = new MutablePeriod();
        assertEquals(20, f.parseInto(result, "P1Y2M3W4DT5H6M7.008S", 0));
        assertEquals(expect, result);
        
        try {
            f.parseInto(null, "P1Y2M3W4DT5H6M7.008S", 0);
            fail();
        } catch (IllegalArgumentException ex) {}
        
        assertEquals(~0, f.parseInto(result, "ABC", 0));
    }