Hi Kys91.
At King Radio Corp., I was responsible for testing avionics to insure quality. My duties required electronic and mechanical knowledge of the products (I would work with the designing engineer to learn the circuits and operation) in order to write specifications and procedures (which were used by the bench techs to align the radios etc). I also specified test equipment used in order to meet the engineering specs. Our products included Transponders, Nav. receivers, VOR/ILS indicators, Servos, and Communications equipment.
All of these products needed to be burned-in (powered in hot environment), put through vibration test, and altitude tested (we used vacuum chambers). If anything failed, the equipment would be repaired and put through all the test again. I've seen radios in the system for a year or so before they were given the okay. Quality was very important as one would expect; life depended on them working correctly.
Avionics is just one area of electronic applications. So if you can stay in school and get a good education in electronics, you will be set for that and lots of other interesting applications.