How can you make sure that a person is your true friend?

They say gold shines most when it is hot.....Genuinity of every relation can be tested by putting it in some stress situation....I have an idea...First fake a quarrel with ur friend with an obvious fault from ur side....then put urself in any apperent stressful situation & call him for help...if he responds with all his heart...then my brother he is the one....have a fine day

You may never really know for sure. I suppose you have to allow time and have trust in that person. A little faith in humanity is helpful also.