My porch light suddenly does not work at all. I have tested the switch, the bulb and the fixture seaparately and they all are good. I checked the switch with power on with my neon tester and both the live and neutral light up the tester. I disconnected the cable going to the fixture at the switch and inserted the fiture directly to the incoming cable and it works fine. Does that mean my house wiring is faulty? This is original wiring since the house was built over 20 years ago and has never been tamperered with? Can the cable become faulty although it is behind the walls?

Also if it is the cable that is faulty is it an expensive job to get it replaced since it would require tearing down the walls?

I would apprecaite any suggestions.