Again, if all you want is "is light passing through the fiber strand" you can just get a fiber pen: https://www.amazon.com/KELUSHI-Portable-Universal-Connector-Telecommunications/dp/B01I3LRATQ

with a corresponding optical power meter: https://www.amazon.com/Qiirun-Optical-Calibrated-Wavelengths-Weighted/dp/B07X7HWBPG

But if you want actual testing and certification, the price goes up, fast.