Testing relays

[kridgley at brownscar.com (Kervin Ridgley)]

I gotta get my car inspected before the end of the month.  My horn stopped working a while back and if they check it (not very likely) and it doesn't work, I fail.  This morning, I tested the horn button and that is fine.  The fuse looks good.  The contacts to the relay are clean, but I'd like to test it.  Tomorrow, if it doesn't snow too much, I'll hook the horn directly to the battery to make sure it works too.  Anyway, how do you test a relay?