I think if you wish to do the test and get the certification, it's fine. It's really up to you. But, I wouldn't expect future employers to put much worth into the actual certificate.
I think most(employers) want to know if you are able to think on your feet, be able to actually code at whatever level you're at... and be open to learning. I'm sure there are other/more qualifications, but having a certificate.. especially from an online test isn't going to be too impressive.
in reply to Expert programmer's certification