Add gcov code coverage to the test suite

scripts/coverage.py configures an instrumented build tree
(-DAKERR_COVERAGE=ON), runs the CTest suite in it, and reports merged
gcov line/branch/function coverage per library source. Like the mutation
harness it has no third-party dependencies and supports --threshold and
--junit; thresholds gate each file as well as the total so the generated
status-name table cannot mask a regression in src/error.c.

Only the library is instrumented. The public header's macros cannot be
measured this way -- GCC attributes an expanded macro to its call site,
so header logic would report as lines of the test that used it -- which
is what mutation testing against include/akerror.tmpl.h is for.

Coverage flags are applied per target rather than globally, so they do
not leak into the exported/installed target interface.

Current numbers for src/error.c are 94.0% line and 59.5% branch; the CI
gate is set to 90/50 to keep headroom, matching the convention used for
the mutation score threshold.

Tests run: ctest (23/23), cmake --build build --target coverage,
threshold gate verified failing at --threshold 99, cmake --install
checked for flag leakage, out-of-tree --build-dir checked.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Co-Authored-By: Andrew Kesterson <andrew@aklabs.net>
This commit is contained in:
2026-07-30 01:48:07 -04:00
parent f4dfb3acb9
commit ee3ff2564c
5 changed files with 517 additions and 8 deletions

View File

@@ -34,6 +34,20 @@ cmake --build build --target mutation
scripts/mutation_test.py --target src/error.c --threshold 65
```
Code coverage is available through:
```sh
cmake --build build --target coverage
scripts/coverage.py --threshold 90 --branch-threshold 50
```
`scripts/coverage.py` configures its own instrumented build tree (default
`build/coverage`, `-DAKERR_COVERAGE=ON`), runs the CTest suite there, and
reports gcov line/branch coverage per library source. Thresholds gate each
file as well as the total. Coverage measures `src/error.c` and the generated
`src/errno.c` only; the public header's macros expand at their call sites, so
mutation testing is what checks those.
## Coding Style & Naming Conventions
Use C99-compatible C and follow the surrounding style. Functions and types use
@@ -48,8 +62,9 @@ Add tests as `tests/err_<behavior>.c`. Register each new test in the
`AKERR_TESTS` list in `CMakeLists.txt`; tests that intentionally abort must
also be listed in `AKERR_WILL_FAIL_TESTS`. Prefer focused executable tests that
return zero on success and use existing helpers such as `AKERR_CHECK`. Run the
CTest suite before submitting changes, and run mutation testing when changing
core control-flow, reference counting, stack-trace, or handler behavior.
CTest suite before submitting changes, and run mutation testing and coverage
when changing core control-flow, reference counting, stack-trace, or handler
behavior.
## Commit & Pull Request Guidelines