When I used to be the test chair, I would use this position like Cara said. Usually they would stand by the door and answer questions, help keep the session moving by tracking down/marking off skaters.
We never used announcer. We did see this at a club my DD regularly tested dance at. All the test forms were numbered. The announcer would call out the skater name, sheet number, and test. I could see how this would come in handy. At one of my sessions, I had 5 Juvenile Free Skates and one of the judges mixed up the forms. I started numbering my sheets after that.
ETA: as a former test chair - Thank you for helping out. It makes the chair's job a lot easier to have helpers.