If you are in a tribe not hating on pp-macros, you might find this approach for testing/debugging data structures (or even the surrounding pp-based "CTL"-like C templating idea or abstract ways of dealing with the BST zoo) interesting:

    https://github.com/c-blake/bst/blob/main/test/bst-interact.c

Essentially, you just write a very simple (some might say trivial) interactive command-shell that can include an auto-checking upon edit of (in that case tree) invariants keyed-off an environment variable. The only missing piece is some little tool to generate random inserts/deletes/etc.

If the micro-shell has a pretty printer then it is easy to "replay" any failed series of edits with some "p" commands before & after invariant failures.