I might undergo operation for inguinal hernia. my question is that will the doctors find out through the tests they do that i smoke pot or may that information be necessary to share with them as i heard it is required to administer anaesthesia dosage?

Routine lab tests don't check for drug use; a specific test must be requested. In North America or Europe, hernia surgery isn't usually a reason for drug testing; I don't know about such policies in your country or hospital.

Yes. For your own safety please tell the anesthesiologist. They are not judgmental. It is best to refrain from it for several weeks before surgey.