How do you know if you have good friends?

This is a tough question & it would definitely take time to figure out. A true friend would be there when you need them, keep a secret if you told them, etc. I would say the only way to really know is the next time you need them, are they there? Or have you told them something no one else knows, but somehow someone else found out? This obviously means your "friend" told someone. Or if you are upset, do they appear to be genuinely concerned. Friendship takes time. Make sure you aren't too trusting in the begining. And just look for the signs that they may not be true. Even possibly, see what their other friends or family think about them..