Why we need testing?
Is it to find bugs?
Is it to prove that software have issues?
Actually the common need of testing is not only to prove that software have issues or to uncover bugs only. What really testing does is very important question. Let we take an example.
Today laser surgery for removing glasses is very common, but if you have to go for it, how you will be sure that it will OK for you?
Most of us will first want to know that it will not harmful for us. Laser surgery is working fine that has been proved by testing, but it will not have any side effect on your body, who will prove it?
Testing creates the faith of customer in product and that is the true testing. Still it may the case that one product useful for someone may be useless for other. It all depends on users.