I dunno why you need a meter. YOu block the vents
and the main drain, mark the water level in the toilet,
and blow air into the system until the water in the
bowl rises an inch. Then come back in however long
it's supposed hold the pressure and see if the water level
has gone down.

Thanks MLD and Goedjn. You've been helpful.

Another question I have about all this is, where do I pump the air in?
For the first test, I pumped air into the sink drain line where it
enters the wall. But for the second test, that sink (as well as the
toilet) will be installed, so I can't pump air at that spot. I'm
guessing I'm going to have to add another test tee?

Or do I actually blow air into the system via the u-shaped tube that I
will be sticking into the toilet?

Thanks again for your help.

Tim F.