Pat's thread brought up an idea I have been noodling on, as well as one of the answers on that thread, discussing the nuanced difference between a good test and a hard course. I have always agreed with this. In a way, target size and receptivity, given shot length, wind, elevation, etc. sort of sets the "test level." In other words hitting a 3 iron to a small green (or small target within a green) is always a test. Hard might be the difference between a gentle fw chipping area surrounding the green vs loads of deep sand bunkers, water, or what not.
Sound like a reasonably fair generalization?
Another criteria we often hear thrown out is "requires you to hit all the shots." Some would define that fairly simply as using every club in the bag, but I think better players would include ball flight, including curvature, height, and what kind of lie they hit off of, as well as a variety of wind conditions to define "all the shots." You might add in high and low spin.
For instance, high fade into the wind, cross wind left, cross wind right, downwind. And then low fade, high and low draws, etc., in the same 4 wind conditions.
We might add a mixture of mental states, as in fear of water (cape hole, island green) and a few easier holes that just might lull you to sleep. For that matter, mixing hazard close to one side of green, and bail out areas on the other side to cause temptation/indecision would be a better description, and of course lead to choices.
So, my list includes:
Reasonable but difficult targets, (perhaps a mix for variety)
Design that suggests the best shot may have certain patterns to it to best assure success.
Some flat out terror (can be overdone.....)
Options (Indecision/Temptation/Doubt).
What else needs to be factored into a good test of golf? BTW, we presume that inspiration, usually coming from great natural setting, while not a test of golf, would also need to be included to make it a great course.