I have never seen anyone test for wind uplift on a roof before, but i know that it is done by companies such as Factory Mutual in their laboratories. Uplift is measured by pounds per square foot. The amount of wind uplift on your roof depends on a lot of things such as your building height, the terrain around it, parapet walls, decking, etc. FM has tested in their labs wind uplift at different levels and developed roofing systems for that particular wind level. So for example FM has roof classifications such as I-60, I-90 and I-120. Each one is at a different wind uplift rating and each system has to be installed with certain decking, insulation thickness, amount of fgasteners per board, etc. It gets a little complicated but if you know what type of roofing system you have and what type of deck you can figure out a round about number that your roof system should be able to handle. As for a tool to test on the roof i have never seen one other than a fastener pull test tool. (doesn't mean there isn't one out there LOL) Sorry for the long explanation.