Vegetable seeds, how to test viability

I've been slowly sorting through the vegetable seeds I have here - those saved from my own garden and those bought from places like Green Harvest and Eden Seeds. I now have a list of the vegetables we'll grow this season, I don't have all the seeds yet, and some of the seeds I have I'm not sure of. If you're not sure of your seeds, it's best to test the viability of them before you plant. There