Viability of Yeast

I transferred my first batch of brew from a primary to a secondary about 2 weeks ago and harvested yeast from the primary according to John Palmer's book. I have had another batch in the primary until yesterday and thus am ready for a third batch. The yeast from the first batch is the same strain as I need for the third. Is there a way to test the viability of my harvested yeast before I attempt to pitch it?

Thanks,
Andrew

You can make a starter. The starter should start to ferment and then you'll be able to tell.