Yahoo (YUI) vs Google (Closure) framework for testing on browsers and node.js

It seems that YUI is very focused on providing all the same code for both browsers and node.js.

That's very powerful because now I can use the same tests on both ends and don't have to rewrite/relearn anything.

Is google also focusing on node.js when it comes to testing?

YUI has a very verbose documentation about how to use it, Closure seems to lack this kind of good support.

Is YUI a better library to use on both ends?