Please note that this subject may interest some members only. And I am not sure if what I present here is new or not.
Lately, I had to check the continuity of each wire of a long 8-wire cable which connects two rooms in different floors.
It happens that I had a small signal neon bulb (connected in series with a high value resistor). It is usually used to monitor the AC mains voltage.
On one side, all wire ends of the cable are grounded. On the other side, one terminal of the signal neon bulb is connected to mains phase without forgetting to isolate it well to avoid any risk. As you already guessed, the bulb will turn on every time its other terminal touches a healthy wire... or a finger
For instance, this simple technique is well known, since very long, to test the mains phase terminal by using a screwdriver which has a neon bulb and a resistor inside its transparent body.