Disconnect the hose from the fuel rail......................................and turn the key to ON. The pump will run till the fuel pressure hits it's set point to open the bypass. It will never bypass because the line is going into your fuel can, lawnmower, bathtub, whatever. Turn off key when your floor is covered in a fire hazard.
Simple and as safe as anything else we do.
Side note:
I jumped my fuel pump to empty the tank after I had pulled it and it was sitting on the floor of my shop. I filled 5gal cans for the mower. It actually takes a while to fill a 5gal gas can. My point being, it's not like it will shoot fuel 10' out of the line, it dribbles out, maybe a couples inches at most. It can only create any kind of real pressure when it's closed off.