Gas stove testing?

Hi all,
My question is whether I can test a gas stove with the gas line that goes to a gas hot water heater. I need to sell a couple of Viking gas ranges, and the prospective buyers want to be sure that the range works. I do understand that the line may be a smaller diameter so gas output might be less than desirable, but not sure how to get around this. Since there is only rooftop gas-packs, and gas hot water heaters on site, the only way for me to test them would be to add a gas line (not cost effective for a test), or use the hot water heater line.
Dose anyone have any advice?
Thanks
Kent

 

A smaller line would be ok just for testing purposes.

 

Thank you.
Also thanks for replying.
Kent