Coil tester diagram

[Chuck Sea/Tac]

Is there a link to a simple diagram for a coil tester?
I have a clip soldered to a spark plug, with a pigtail coming off. I hooked it to the neg of battery , and pigtail to minus of coil. Hi tension wire to plug, and then sparked the positive side of coil to positive terminal of battery to simulate points.i get coil spark, but no plug hi tension spark. Have I got this correct? I also tried several different coils, with the same results.