Module co_change 

The commit-scoped co-change check: a source file that changed in a git diff must change its colocated test too.

Functions

stale_sources

Every source file changed in repo’s <base>...HEAD diff whose colocated test did not also change, sorted. A subject whose repo-relative path is in exempt is skipped. Errors when git diff fails, so an un-diffable range surfaces rather than passing as “clean”.