Hello,

It's nowhere mentioned that you can't appear for examination while wearing Abaya but, since it's a state level exam you might need to take off your Abaya from your head. So be prepare for it. At the examination centre, if the examiner or Invigilator asks you to take off your Abaya then I fear that you will have to do this, or otherwise he/she doesn't allow you to appear in the exam. But it's only a possibility, as it is nowhere mentioned that's why Chances are very less that.

Good Luck.