It's been hinted at that the iOS simulator can be resized to show the full size keyboard in the iPad Pro (http://www.fastcompany.com/3047871/tech-forecast/the-ipad-pro-doesnt-need-a-physical-keyboard), which presumably would allow for the testing of an app in that screen size, but I haven't found a way to do it. The GM seed of Xcode 7 even has the iPhone 6S and 6S Plus, but no iPad Pro in sight. Anybody have any ideas?
If you run on the iPad Pro simulator in Xcode 7.1 Beta and use a storyboard (not an assets file) as your launch screen, it works great.