Can the MacBook boot from a second HDD If I was to install a SSD in my MacBook Pro (Mid 12) where currently the Superdrive is attached and continue to use the preinstalled HDD for other files, can I run OSX from that new drive?

Or in other words: Is EFI configured to always use the first SATA to look for a bootable volume, or does it test all attached sources?
I used to run this exact configuration in a 2009 MacBook Pro. It works fine and never had any issues booting from a drive in the CD bay. I used the MCE Tech OptiBay drive bay kit for the second drive adaptor.