How do you know if a ignition coil still works?

Is this a conventional coil, a hei coil, or a coil over each plug?? need more info, but is has a wire, hold approximately 1/4 inch from ground and see if archs, if High Energy coil, hold plug wire about 1/4 in from ground and see if fires, if coil over plug individualy, not sure how to check them. good luck