I'd be cautious about assuming that third-party libraries have been fully checked with their own test vectors, because usually said test vectors do not exist.
You are correct but such libraries must never be used ever in first place.
It is also not defined by NIST which makes finding test vectors for it harder,
You can always find the original author of the hash algorithm and use the test vectors/code that they have provided:
https://homes.esat.kuleuven.be/~bosselae/ripemd160/#Outline