If it is in regards to for example making sure that HUD elements are always displayed correctly etc I did that with my latest game. I basically just put in crazy resolutions on the game in Fusion, like 1500x500 or 500x1500 etc and made sure that things looked ok and that the HUD elements etc where displayed correctly no matter what resolution. I figured if things looks correct in these extreme resolutions I tested they should also look good on less extreme resolutions, but of course it would be useful to be able to test specific devices also.