Think about a new unit testing framework

[maartenuni]

psylib is currently using CUnit for unit tests (https://cunit.sourceforge.net/) which works, but is quite old and not actively supported anymore.

A potentially handy alternative is: µunit (https://nemequ.github.io/munit/)
One of the nice features of the last is, it doesn't only show that an assert has failed, it also shows the values.
Additionally, you'll only have to add munit.c and munit.h and your done, so you can add the sources, use a git submodule, or finally munit may be wrapped using meson