We have developed a framework using YUI 2.9. As the newer versions of browser are released for like a month eg FF. We have to do testing for all the component with newer version. Is there any way this testing can be compromised? YUI 2.9 will be compatible with new browsers?
You shouldn't develop new software with YUI 2. It isn't supported anymore by Yahoo! or the community. YUI 3 sometimes breaks with new browsers and it needs to be fixed, so there's a good chance of YUI 2 breaking.