I don't test them by cutting, nececarily, I just look real close. I look for overall straightness of the edge both when viewed edge-on and when viewed from the face. Also I look for "platform remnants" or grinding marks. I look for tiny hinges and steps near the edge. I look for parts of the edge where the angle is too blunt.
It's hard to describe the sharpening process- I recommend you get with someone who can show you.To make the edge, I use two types of flakes in a specific order- there are tiny little beveling flakes, followed by longer edge-making flakes. When it's all done, the beveling falkes are gone. The final pass of flakes makes the edge- to prepare for this final series- you have to start with an edge that is already pretty damn straight and faces that are very smooth without hinges. Each flake platform in the final series is built by taking tiny flakes, NOT by grinding. Each edge-making flake in the final series connects to the previous flake- you take them all in a row from base to tip or tip to base. These final flakes are "real" flakes that go at least 1/4 of the way across the point- not tiny little 1mm flakes. . To me, the key is learning to build your platforms by flaking rather than grinding, the tiny platform-building flakes(a.k.a beveling flakes) produce a rather steeply beveled edge. For me, these tiny platform building flakes are taken in the same direction as the edge-making flakes and the tiny bevel they produce is not the place where you put your flaker tip, the bevel is on the bottom.I usually take 2 tiny beveling flakes, then one edge-making flake, then move down the edge about 1/8 inch, take two tiny bevel-making flakes, and so on.