Specifically, IKEA uses Objet's Eden500V 3D printer. But do they print furniture? Not as far as we can see, but instead they're using the printer to produce prototypes of utensils and other small objects in their familiar simplistic Scandinavian design style.
National Geographic has posted a video of their process, in which Technician Johan Karlsson says:
The product designer, developer or technician will come down to get it and then they will take a decision if it is good or bad. If it feels good in the hand, the size and shape of it, how it feels to eat with it.
Now that's product testing - eating with it!