Easy way to test rangefinder accuracy?

Suspect that your rangefinder is giving you incorrect distance readings? In Nov 2000, Sal DiMarco Jnr noted these handy tips on a mailing list:

[…] The late Bob Schwalberg once suggested a quick way to do a rangefinder test: for infinity… focus on a cloud. It is far enough away to be infinity. For closer distances, put a lipstick mark on a mirror ([or] black tape) set your camera to one meter and focus by moving the camera in and out. Once you have focused on one meter, move to the side a bit and refocus on the camera body. The scale should say two meters - if it doesn't then it's off. Finally, as he pointed out, even if your rangefinder is off a little, you lose focus at ƒ2.0 but at ƒ8.0 everything will be fine.