public void testForStyle_invalidStrings() {
        try {
            DateTimeFormat.forStyle("AA");
            fail();
        } catch (IllegalArgumentException ex) {}
        try {
            DateTimeFormat.forStyle("--");
            fail();
        } catch (IllegalArgumentException ex) {}
        try {
            DateTimeFormat.forStyle("ss");
            fail();
        } catch (IllegalArgumentException ex) {}
    }