I've done a couple of Excel online test and find them very frustrating to be
honest. I consider myself a very experienced user of Excel but still made
errors in the tests because of the way they are set up. The problem is that
they reply on you doing things in one way and one way only. That means if
you know how to do something but normally have to check a couple of toolbars
to find it then that's a mistake. It even gave me an incorrect answer when I
pressed return instead of hitting ok with the mouse. This is no way to find
out if you're any good at something. I feel that as long as the person gets
there and they are on a time limit then it doesn't matter how they do it.

So look for a test like that. I'm sure if you contact microsoft themselves
they may be able to help.

Carl