The front bumper is similar to the MKVII GTI and not the MKVII Golf R but that also is likely there just to throw people off. It also looks like there is a roll cage in the car. This appears to be a serious roadcourse MKVII Golf considering the lowered suspension, cage, and rear wing.
A 370+ horsepower Golf R EVO has already been announced so this likely is that car. Audi and VW also have announced their intention to build the most powerful 2.0 liter four-cylinder in the world and VW wants that motor for the Golf.
Only Volkswagen likely knows what this is but a hotter MKVII Gold is coming and if VWBoost were to guess that is what you are seeing tested.