Every engineer tests a hypothesis by designing things based on that hypothesis and then testing that they work as intended. We tend to use the hypothesis' that have already been elevated to the status of theory though.
I've done some Greenfield science as an engineer, and plenty of scientists do some engineering. Titles dont really mean that much to me. It's all sort of a continuum and our place on it isn't strictly defined.
Ok let's be real. You're the one splitting hairs now. There is a clear difference between what either occupation does but of course sometimes a scientist needs to do carpentry or machinist work to build the tools for his experiment. Does this make machining and carpentry the same thing as science? No.
I've done some Greenfield science as an engineer, and plenty of scientists do some engineering. Titles dont really mean that much to me. It's all sort of a continuum and our place on it isn't strictly defined.