You can test light fixtures
There are several different types of light fixtures, but the most common ones are the standard home installed types or the portable lamp types. Both of these have screw-in Edison bases that take incandescent bulbs, CFL bulbs or LED bulbs. Fluorescent and other non-standard light fixtures have electrical additions in the basic circuit, such as ballasts, starters and capacitors, and unless you are a qualified electrician, it is simpler to just replace those fixtures than to troubleshoot and/or test them. Does this Spark an idea?
Portable Lamp Light Fixtures
1. Screw in a known good bulb into the light fixture socket. Do not assume the bulb is good because it is new; test the bulb in a functioning light fixture first, then screw it into the one in question. If the bulb does not light up, there is a problem.
2. Unplug and remove the fixture if possible. On portable lamps, remove the shade, followed by the frame that holds the shade on (called a harp). The harp comes off by squeezing the sides and then pulling it up and away. The socket proper will have a “press here” button on the side, which needs to be pressed and then pulled off. That action will expose the actual fixture itself, which you can then pull out of the lamp. Loosen the screws holding the wires on the side by turning them in a counterclockwise direction with either a Phillips-head or flat-head screwdriver. Pull off the wires and the fixture will come free.
3. Place or clip one probe of your continuity tester against the threaded portion of the fixture. Next, place or clip the other probe onto the brass colored screw on the fixture. Turn on the switch and the tester will flash if the fixture is good. If there is no flash of continuity, replace the fixture.
Hardwired Light Fixtures
4. Set your multimeter to the 200 volt setting. This will easily cover any American voltage in the electrical lines.
5. Check the breaker or fuse that supplies power to that particular light fixture, and make sure it has not broken or blown. Either reset or replace if it has, then turn the light fixture on at the switch.
6. Touch one probe of your multimeter or your voltage tester to the inner threads where the bulb resides. Touch the other probe to the bottom button in the base of light fixture.
7. Read the voltage on the multimeter, or watch for the voltage tester light. If the voltage reads 120 on the multimeter or the voltage tester light goes on, the fixture is good. If the multimeter reads zero or the light on the voltage tester does not light, replace the fixture.