Test to determine if universe is infinite or not

Currently it is not known whether the universe is finite or infinite. Is there any test that can be performed (theoretically) to know whether the universe is infinite or not?

I'm still in high school, so it'd be great if the answer provides a more qualitative test rather than a quantitative one, as I doubt I'll be able to understand the mathematics behind it.

• @SamuelMontgomery: your assumption is not safe. We may well find a theory $A$ that matches all experiments and tells us whether the universe is finite or not. That does not mean there isn't another theory $B$ that also matches all experiments but predicts the universe size to be the opposite of what theory $A$ predicts. Apr 27, 2015 at 17:00