I've always published my research code. Thanks to that, one of the tools I wrote during my PhD has been re-used by other researchers and we ended up writing a paper together! In my field is was quite a nice achievement to have a published paper without my advisor as a co-author even before my PhD defense (and it most likely counted a lot for me to get a tenured position shortly after).
The tool in question was finja, an automatic verifier/prover in OCaml for counter-measures against fault-injection attacks on asymmetric cryptosystems: https://pablo.rauzy.name/sensi/finja.html
My two most recently published papers also come with published code released as Python package:
- SeseLab, which is a software platform for teaching physical attacks (the paper and the accompanying lab sheets are in French, sorry): https://pypi.org/project/seselab/
- THC (trustable homomorphic computation), which is a generic implementation of the modular extension scheme, a simple arithmetical idea allowing to verify the integrity of a delegated computation, including over homomorphically encrypted data: https://pypi.org/project/thc/