How to test a new (Ultra Wide) lens - Sigma 8-16mm?

I tested and put a 24-hour hold on this lens.

Camera store is in an office park and strip mall with a lot of brick buildings. Day was very sunny. I simply shot (RAW) many photos of the brick buildings at various f/stops and focal lengths, then shot into the sun, away from the sun, at trees across the street, etc, all without leaving the store parking lot and the direct view of the sales person. It took me about 10 to 15 min to do all this, using very high shutter speed because I didn't have the sense to bring my tripod. Then I handed back the lens after noting its serial number, told them I would be back by end of next day for that serial number lens. That evening I reviewed all my pix , noted center and all corners, found that the lens was a good one. I bought that serial number lens and have been happy with it.