Hi,
You need to discriminate between open and shorted cable conductors (And BTW wether the cables were wired correctly, which affects microphone phasing.)
You would like to know if the insulation is good.
One approach, which I used in testing Arduino inputs and outputs, is to connect two high value (say 100,000 ohms) resistors in series from +5V to Ground, with the center to each cable conductor. Start by reading the voltage at each conductor. It should be very close to 2.5V if the insulation is good.
(See the Arduino testing application HERE )
Then drive each conductor from the "send" end (in series with 220 ohms to protect the Arduino output pins), to both 5V and Ground and read those voltages. They should be close to 5V and Ground. The 100K resistors have little effect on that.
You could make a short XLR-Male to Female cable with the conductors connected to the test setup, maybe on a piece of protoboard.
Then you can test the tester by mating the two connectors, and then unplug and add cables in series to test.
It might be good to have the test run constantly, alarming any faults, so you can twist and abuse the cables and connectors to see if there are intermittent shorts/opens.
And as my Dad taught me in 1950, if you find a bad cable, immediately tie a figure-8 in both ends, so no one will mistake it for a good one... And when you get back to the radio station, you'll pull it right out of the cable bag and put it on the bench.