Files
libakstdlib/AGENTS.md
Andrew Kesterson 437da2960b Test the libc wrappers: 52% -> 99% line coverage
Every wrapper outside the list and tree code was untested. Six new test
files close that, following the plan already written in TODO.md 1.2-1.6:

  test_stream.c   fopen/fread/fwrite/fclose -- happy paths, the round
                  trip, AKERR_EOF on a short read, AKERR_IO on a stream
                  opened in the wrong mode, ENOENT, and the NULL guards
  test_format.c   printf/fprintf/sprintf -- text *and* count asserted
                  (stdout is pointed at a temp file to check aksl_printf),
                  all eight NULL guards, EBADF on a read-only stream, and
                  512 variadic calls in a loop as sanitizer cover for the
                  missing va_end
  test_convert.c  ato{i,l,ll,f} happy paths, negatives, leading
                  whitespace, NULL guards
  test_path.c     realpath on a file and on a symlink, both compared
                  against realpath(3) since TMPDIR may itself be a link;
                  ENOENT, ENOTDIR, NULL path
  test_strhash.c  djb2 known-answer vectors, len == 0, embedded NUL,
                  stability, NULL guards
  test_convert_strict.c
                  known-failing (2.1.5): the AKERR_VALUE / ERANGE
                  contract the ato* family cannot express today

test_tree.c gains the BFS AKERR_NOT_IMPLEMENTED contract, NULL arguments,
and a callback error that is not AKERR_ITERATOR_BREAK propagating out.

Tests deliberately say nothing about behaviour TODO.md records as
defective -- unchecked ptr/mode/resolved_path, short transfers reported as
success, *count left at -1, the djb2 sign extension -- so the eventual fix
does not have to come with a test rewrite. Each failure case in
test_path.c passes a zeroed buffer, because the wrapper's own error path
formats resolved_path with %s (2.1.6).

aksl_capture.h gains aksl_temp_file() with an atexit unlink backstop.
Without it every test that fails before its own unlink leaves temp files
behind -- which is the normal case for a known-failing test, and happens
173 times over in a mutation run.

Coverage on src/stdlib.c: 52.0% -> 99.0% of lines (200/202), 23.6% ->
51.0% of branches, 8/21 -> 21/21 functions. The two uncovered lines are
both `} HANDLE(e, AKERR_ITERATOR_BREAK) {`, where the macro starts with
the `break;` of PROCESS's `case 0:` arm -- reachable only via a non-NULL
error context whose status is zero, the pathology 2.2.1 exists to remove.

Mutation score on src/stdlib.c: 46.8% -> 89.6% (155/173 killed). CI, the
pre-push hook and the docs ratchet from 40 to 80 accordingly, and the 18
survivors are grouped by cause in TODO.md and README.md. A new CI
coverage job gates at 90% lines / 45% branches.

Verified:
  ctest --test-dir build            # 12/12
  ctest --test-dir build-asan       # 12/12 under ASan + UBSan
  ctest --test-dir build-coverage   # 14/14, report attached
  ctest --test-dir build -j8 --repeat until-fail:3
  gcc -Wall -Wextra -c on all nine test files  # no warnings
  python3 scripts/mutation_test.py --target src/stdlib.c  # 89.6%
No temp files left in /tmp after any of the above.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-07-30 02:07:36 -04:00

3.5 KiB

Repository Guidelines

Project Structure & Module Organization

libakstdlib is a C shared library that wraps libc calls and small data structures in libakerror error contexts. Public API declarations live in include/akstdlib.h; implementation lives in src/stdlib.c. Tests are one-file CTest executables under tests/test_<name>.c, with shared test helpers in tests/aksl_capture.h. CMake package templates are in cmake/ and akstdlib.pc.in. The vendored dependency is deps/libakerror; update it as a submodule rather than editing generated files under build/, build-asan/ or build-coverage/.

Build, Test, and Development Commands

Initialize dependencies before a fresh build:

git submodule update --init --recursive
cmake -S . -B build
cmake --build build

Run the normal suite with ctest --test-dir build --output-on-failure. Use the instrumented build for memory and undefined-behavior checks:

cmake -S . -B build-asan -DAKSL_SANITIZE=ON
cmake --build build-asan
ctest --test-dir build-asan --output-on-failure

For coverage, configure a third tree; the report is part of that suite (the coverage_reset / coverage_report CTest entries) and also lands in build-coverage/coverage-summary.txt:

cmake -S . -B build-coverage -DAKSL_COVERAGE=ON
cmake --build build-coverage --target coverage

Run cmake --build build --target mutation only when you need the slower mutation harness. rebuild.sh installs to /home/andrew/local and removes the local build directory, so treat it as a local convenience script.

Coding Style & Naming Conventions

Use C with 4-space indentation; existing files sometimes use tabs for continued statements, so match the surrounding block. Public symbols use the aksl_ prefix, structs use aksl_<Name>, and tests use test_<feature>.c plus static test_<case> functions. Preserve the akerr_ErrorContext AKERR_NOIGNORE * return convention and the PREPARE_ERROR / FAIL_* / SUCCEED_RETURN pattern.

Testing Guidelines

Add a new test by creating tests/test_mything.c and adding mything to the right list in CMakeLists.txt. AKSL_TESTS must exit zero. AKSL_WILL_FAIL_TESTS are deliberate abort/contract tests. AKSL_KNOWN_FAILING_TESTS assert documented defects from TODO.md; when one starts unexpectedly passing, move it into AKSL_TESTS with the fix.

src/stdlib.c is at 99.0% line coverage and CI gates it at 90 (line) / 45 (branch), so new code needs tests in the same commit. Run cmake --build build-coverage --target coverage and check the uncovered-line listing before proposing a change. Tests for behaviour that TODO.md records as defective belong in AKSL_KNOWN_FAILING_TESTS asserting the correct contract — do not pin current-but-wrong behaviour in AKSL_TESTS, since that turns the eventual fix into a test failure.

Commit & Pull Request Guidelines

Recent commits use short imperative summaries, for example Add memory wrapper tests and Make error-status assertions authoritative. Keep commits focused and include tests with behavior changes. Pull requests should describe the changed API or behavior, list the CTest/sanitizer/mutation commands run, and link the relevant TODO.md item or issue when fixing a known defect.

Agent-Specific Instructions

Do not modify generated build trees, profiling artifacts, or untracked scratch files unless explicitly asked. Prefer small, test-backed changes and update README.md or TODO.md when changing documented workflows or known failures.