I was going to ask the same. I can listen while drawing, or playing games. but if I'm trying to do something like reading a document or writing a letter/email I find that one of the my "channels" just shuts off... So either I dont register the audio or my reading/writing goes to shit and i find myself stopping or re-reading the same line 15 times....
It depends what you're coding. Sometimes you're really just following an existing pattern, and doing essentially grunt-work.
If it's something new and requires some thought, then nooo lol you're not going to be able to take in any of that audio book, it's just going to be distracting.
Depends on what kind of tests you're writing, but even there I'd say it takes too much concentration to do both. At least if you don't want to miss 50% of the fragment you're listening to.