Testing involves visual inspection of terminations with a microscope, tracing fibers visually and finding faults, measuring optical power and loss with power meters and light sources, testing with OTDRs and testers for special issues in long distance links. Fiber Optic Testing Testing is used to evaluate the performance of fiber optic components, cable plants and systems. For every fiber optic cable plant, you generally need to test for continuity and polarity, end-to-end insertion loss, verify installation with an OTDR and then troubleshoot any problems on every fiber in every. For every fiber optic cable plant, you need to test for continuity and polarity, end-to-end insertion loss and then troubleshoot any problems. If it's a long outside plant cable with intermediate splices, you will.