I can't recommend www.tacticalvideoworks.com/products enough. Patrick sells Cable and port testers as well as a variety of 3D printed accessories. I had some issues with UPS and reached out to him. He responded quickly and took care of my issue with UPS at his own cost.

I honestly haven't even tried the BNC tester I bought yet and I can already tell you I would buy from him again in a heartbeat.

Edit: Used the tester in prep today. Works as advertised. Super simple to use.