The first impression is that the best way to test a CVT fluid would be to put it in a car containing a CVT transmission, and then verify that it runs without any problem. But in fact, this chassis dynamometer testing method does not allow testing the limits of the fluid.
In order to really test these limits, the best way is then to put a CVT between electric motors, and progressively apply load until the limits appear. But going to the limits will weaken the CVT itself, especially the belt. Besides, this testing method is far from simple, requiring a lot of money, fluid, and time.
Therefore, it is necessary to find a suitable and simpler testing method that would give some similar results. The idea is then to use some usual tribometers, like the LFW-1.