Test to see if yeast is good?

[Kassad]

So I've had a package of white labs wlp001 sitting in room temperature for a couple months (I forgot about it) and am wondering if it still usable. I was planning on pitching in a 1 gallon batch so i don't need all of it which brings me to my question - Is there any test, or way to tell if it still good? Obviously if the OG doesn't drop after pitching that's one indication, but perhaps some other way without having to add it to wort to know if it's good?

If there isn't and I do decide to pitch, am I harming the wort if the yeast is dead? Can i just pitch some more yeast after 4 days of inactivity?

 

[cubalz]

Uh, that yeast is most assuredly dead. Way dead. Don't use it, throw it away.

 

[flars]

Make a "shaken not stirred" 1/2 liter starter. Aerate the starter wort until you have turned most of the wort to froth. A krausen will form after the froth settles if there is still some viable yeast. Give the starter at least 24 hours to show some activity.

 

[kh54s10]

I would make a small starter. There are certainly very few (if any) live cells left. If the starter goes then you have some fresh healthy yeast cells to pitch. If you don't make a starter you are using unhealthy yeast that will expend a lot of their energy reproducing before the new cells start fermenting the beer.