The answer to 'how to test lighting installation' is to systematically check each lighting fixture and circuit to ensure they are working properly. Start by turning on all the lights and visually inspecting each one to make sure they are illuminating correctly. Then, use a voltage tester to check for power at the light fixture and at the circuit breaker or switch controlling the fixture.
If a light is not working, first check the light bulb and replace it if needed. If the bulb is good, use the voltage tester to check for power at the fixture. If there is no power, the issue may be with the wiring or a tripped circuit breaker. You can then troubleshoot the circuit by checking connections, replacing any damaged wires, and resetting the circuit breaker. It's a good idea to test lighting installations periodically, such as once a year, to catch any problems early.