I've read a lot about the thumb test, not to be confused with the thumbNAIL test. But I can't figure out exactly how the edge is supposed to contact your thumb.

Do you brush your thumb along the blade, away from the spine and out and off the edge? (You'd be brushing the bevel, starting on the spine side and moving out over the edge.)

Do you somehow touch the actual edge with the pad of your thumb?

How do you hold the razor during all this?

Photos would be very helpful. I'm hoping to learn this as a supplement to the hanging hair test, which I think I understand, even though I can't get my razor to pass yet...