I have heard of this type of test using postage stamps. It would not "kill" your penis. The paper band would be snug, close to the shaft, not tight. Some types of paper and tape, I can imagine, are strong enough so that even with an erection, they will not rip and would not be a proper test. Of course, this is unnecessary if you are knowingly waking up in the morning with an erection or you can attain an erection sexually, whether by masturbation or with a partner.