What kind of test can confirm that a person is paranoid? My husband is methamphetamine user and I think he is paranoid. What would I do to help him

Lovehim or leavehim. Meth is renowned for causing delusional thought that can be paranoid in nature. There is no test. If someone is reacting to a perceived threat that doesn't exist, then they're being paranoid. When a meth user stays awake too long they become more delusional and if they are withdrawing they become irritable and the delusions take on a darker tone. If he's violent, leave. The rest is up to him.
Stop meth, get help. Paranoia is common in amphetamine abuse. There is no "test" for paranoia. It is detected in interviews with a trained professional, and can show up on psychological tests. The best help you can offer is assisting him in stopping meth, probably with the help of mental health or drug abuse professionals. It's very hard unless he recognizes he has a problem. Show him your concern, if it's safe.
Take care of you too. I agree with ms. Yang and would add that there are some things you can do for yourself to help improve your chances of helping rather than aggravating the situation. Al-anon is a support group for people whose dear ones are caught in addiction to alcohol or other drugs. It successfully promotes sanity in the midst of the insane world of living with an addict.