so you bought a coil a year ago. havn't run the tractor and now think it's a bad coil?
unless you got unlucky and got a bad one outta the box.. i doubt your coil 'spoiled' from setting there a year.
put a test lamp inline with your coil and roll the engine over with key on. lamp should blink.
don't throw any more parts at this issue till you understand how it works and how to troubleshoot it.