I agree with Preston. I think oDesk has a really great choice of tests and certification tests as well + they are all free (on Elance you would have to pay certification tests.) I did both (more than thirty) and the ones on oDesk are better by far (I had equally high scores on both, so that doesn't affect my judgement.) Also I am pretty sure that on Odesk you have a greater selection than you have on Elance in all areas.
I think the original question was not about the number of tests on odesk but its telated to the skills that you can display on your profile. I am not sure tho.
And I thought:
As we all are aware of M&A of Elance-oDesk, there are various factors to settle for both parties involved in M&A. Need not to name but everyone has “Pros” & “Cons”.