rng-tools includes a command for testing random number generator output. I tried this with a FreeBSD port from https://github.com/waitman/rngtest

Results aren't great:

    rngtest: bits received from input: 300032
    rngtest: FIPS 140-2 successes: 0
    rngtest: FIPS 140-2 failures: 15
    rngtest: FIPS 140-2(2001-10-10) Monobit: 15
    rngtest: FIPS 140-2(2001-10-10) Poker: 15
    rngtest: FIPS 140-2(2001-10-10) Runs: 15
    rngtest: FIPS 140-2(2001-10-10) Long run: 0
    rngtest: FIPS 140-2(2001-10-10) Continuous run: 0
    rngtest: input channel speed: (min=236.690; avg=245.396; max=251.742)bits/s