cmp-cov

Compare local pytest coverage against a saved baseline.

Usage

# After running pytest --cov, save current coverage as the baseline:
uvx cmp-cov save-baseline

# Later, after another pytest --cov run, diff against the baseline:
uvx cmp-cov diff

Both subcommands take an optional baseline name (default default); each name is a separate slot, so multiple baselines per project coexist:

cmp-cov save-baseline main
cmp-cov save-baseline before-refactor
cmp-cov diff main

save-baseline snapshots the current .coverage (SQLite) and source files into ~/.cache/cmp-coverage/<encoded-project-path>/<name>/. diff regenerates current coverage XML, translates baseline line numbers through the snapshotted sources (so source edits between save and diff are handled), and prints per-line diffs grouped by category. Exit code is non-zero if total coverage dropped or any regression / new uncovered line was found.

Each output location is rendered as path:line so it is clickable in editors that support terminal links (e.g. VSCode).

Output categories

• ↓ covered → uncovered — lines that were covered in baseline and are not anymore.
• + new uncovered — lines added since baseline that are not covered.
• ↓ covered line removed — lines that were covered in baseline and have been deleted from the source. Path points at the cached baseline snapshot.
• ↑ uncovered → covered — lines that were not covered in baseline and are covered now.
• + new covered — lines added since baseline that are covered.
• - removed line — non-covered lines that were removed.
• ! unmeasured in baseline (uncovered) — lines in files that were not measured by the baseline run, currently not covered.
• ! unmeasured in baseline (covered) — same, but covered now (compact view).