How to test functionality of a keyboard (when buying used)?

[ShangMingg]

I believe that I've found a deal that may be to good to be true, involving a used mechanical keyboard (a few weeks old).

Is there any way to guarantee that the keyboard works? I'll bring my laptop to test the basic functionality of the keys, of course, but are there other methods such as some kind of software or specific physical keystrokes I can use to test?

Thanks!

[jeroplane]

One popular key testing application is Aqua Key: http://geekhack.org/index.php?topic=34670.msg641440#msg641440

[Skull_Angel]

Could use Aquakeytest; you need to physically actuate the keys, but it'll record which keys you've pressed if they register (on-screen display).

edit: beaten to it!