Capping old drain lines

I have a full bath in my garage that I am in the process of permanently removing. I took out the bathtub and the toilet but I plan on leaving the sink. My question is what is the best way to cap the drain pipes. The toilet drain is 4" cast iron and the bathtub drain is cast iron as well but it has a piece of 1-1/2" pvc attached to it.

Use "dollar" test plugs, they have a wing nut on top that tighten down to seal off the drains,
that way if you ever have a need to open one you can do it by just removing plug other wise that are good for 50 years or more