The first thing you need to check down when on checking out for restaurant chair and tables is its comfort level. Sit and check with different angels of comfort the chair is providing. Check the posture of sitting on the chair. Check the back support of the chair whether it is straight, bent, curved, etc. how the posture of the body is fitting.
What kind of cushion is mounted and whether it is hard or soft. Sit for a longer time and check whether the chair is comfortable for long sitting hours or not. All these aspects come under the testing comfort of the chair.