Let me explain the test a little clearer. I'm talking about how far the fan will go with one push.
Yes, of course if you keep pushing it again and again it will keep going around. But with one push it should not freewheel very far.
The fan clutch controls how tightly coupled the fan blade is to the engine shaft running it. Under cool conditions, the fan doesn't have to move much air - so to save engine horsepower the fan clutch slips a lot. However, under hotter conditions more air is needed, and the fan clutch tightens up to make the fan run harder.
Hope that explains it better!