Lands L3 of the agent-first coverage architecture (ADR-020) — the
mutation-testing layer. Stryker on entities + use-cases (the pure
business-logic surface) catches the third dimension of test quality:
tests that exist + execute the code but assert nothing.
Deps (root devDependencies):
- @stryker-mutator/core ^8.7.0
- @stryker-mutator/vitest-runner ^8.7.0
Shared base: packages/core-testing/stryker.base.json
- testRunner: vitest (uses each feature's vitest.config.ts)
- mutate: src/entities/** + src/application/use-cases/** (excludes
tests, factories, contracts)
- thresholds: high 90 / low 80 / break 80
- reporters: progress + html + json (reports/mutation/{index.html,
mutation.json})
- incremental mode enabled, concurrency 4, timeout 10s
- exposed via @repo/core-testing/stryker.base.json subpath export
Per-feature config: packages/auth/stryker.config.json
- 4-line file that extends the shared base
- Proof-of-concept; other features get a config when L0 unification
closes their existing test gaps
Driver: scripts/coverage/mutate.mjs (zero-dep Node ESM)
- discoverStrykerConfigs: walks packages/* and apps/* for
stryker.config.json
- Supports --filter <name>, --since <ref> (incremental), --json
- Runs Stryker per-feature via node_modules/.bin/stryker run
- Surfaces per-package pass/fail summary; exits 1 on any failure
- Tests: scripts/coverage/mutate.test.mjs (3 tests, all green)
CI: .github/workflows/mutation-nightly.yml
- Cron at 02:30 UTC + workflow_dispatch with filter input
- Uploads reports/mutation/** as artifact (30-day retention)
- On failure, opens a tracking issue labelled mutation-testing
- permissions: contents: read, issues: write
- 60-min timeout (Stryker is slow by design)
Generator: turbo gen feature now scaffolds stryker.config.json from
turbo/generators/templates/feature/stryker.config.json.hbs — new
features ship mutation-ready out of the box.
Guide: docs/guides/coverage.md L3 section fleshed out with run
syntax, config shape, base config inventory, CI behavior, and a
"what you're looking for" primer on mutation scores.
Lockfile churn: pnpm regenerated the lockfile for the new deps;
~5K-line net reduction is collateral (pnpm version drift) but
mechanical.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Lands L2 of the agent-first coverage architecture (ADR-020) — the
aggregated trend store.
Script: scripts/coverage/aggregate.mjs (zero-dep Node ESM)
- discoverLcovs: walks packages/* and apps/* for coverage/lcov.info
- normalizeLcov: rewrites SF entries from package-relative (vitest's
output) to repo-relative, so the merged file matches git diff paths
- summarizeLcov: computes statement/branch/function/line percentages
from LF/LH/BRF/BRH/FNF/FNH summary records
- aggregate: merges all lcovs and returns mergedLcov + summary
- Writes coverage/lcov.info (gitignored — large) and
coverage/summary.json (committed — trend via git log -- ...) with
timestamp, short commit SHA, repo + per-package percentages
Test surface: scripts/coverage/aggregate.test.mjs (10 tests, all green)
- Fixtures at __fixtures__/aggregate-pkg-a.lcov +
aggregate-pkg-b.lcov (synthetic, structured to make percentages
deterministic)
- Covers: path normalization (prefix, absolute, double-prefix
avoidance), summary computation (percentages, zero-division,
rounding), discovery (packages + apps, missing dirs), full
aggregation in a tmp repo
Wired:
- root package.json adds "coverage:aggregate" script
- .gitignore restructured: per-package coverage/ stays ignored,
aggregated /coverage/ ignored EXCEPT summary.json (committed for
trend) and .gitkeep markers
L1 allowlist fix folded in (scripts/coverage/diff.mjs):
- The previous (^|/)coverage/ regex accidentally caught
scripts/coverage/* — replaced with anchored patterns
(^coverage/, ^packages/*/coverage/, ^apps/*/coverage/)
- Allowlist scripts/ and turbo/generators/ since they're dev tooling
tested via node --test, outside vitest's v8 lcov pipeline
Smoke-tested end-to-end:
- pnpm coverage:aggregate merged 3 lcovs (auth + media + navigation
from this session's earlier runs), repo coverage 95.22% statements
- pnpm coverage:diff against HEAD~1 with the new merged lcov reports
PASS — all 6 diff files correctly allowlisted
First committed snapshot of coverage/summary.json lands with this
commit, anchoring the trend history at this state.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Lands L1 of the agent-first coverage architecture (ADR-020) — the
cover-the-diff gate. Reads a merged lcov + git diff against a base
ref, asserts every changed *executable* line was exercised.
Script: scripts/coverage/diff.mjs (zero-dep Node ESM)
- parseLcov: SF -> Map<line, count>; only DA records read
- parseGitDiff: parses --unified=0 output into Map<file, Set<line>>
- computeDiffCoverage: cross-references both, emits result tree
- Allowlist of paths that don't gate (tests, configs, docs, .sh,
DI bootstrap, interfaces, CMS, factories, contracts, UI)
- Path matching handles three lcov path conventions: absolute,
repo-relative, and per-package relative
- CLI flags: --base (default origin/main), --lcov (default
coverage/lcov.info), --json (suppress stderr summary)
- stdout: machine-readable JSON for the dispatch loop
- stderr: human summary
- Exit 0 on pass, 1 on fail or error
Test surface: scripts/coverage/diff.test.mjs (14 tests, all green)
- Fixtures at scripts/coverage/__fixtures__/{sample.lcov,sample-diff.patch}
- Covers: lcov parsing, diff parsing, pass path, uncovered lines,
non-executable line skipping, no-coverage-data detection,
allowlist filtering, end-to-end mixed case, path matching
Wired:
- root package.json adds "coverage:diff" script
- .gitignore anchored so per-package coverage/ stays ignored but
scripts/coverage/ stays tracked
Smoke-tested end-to-end against packages/auth/coverage/lcov.info —
correctly skips shell scripts + manifest files (via allowlist + path
suffix match), correctly flags files not present in the per-package
lcov (which is expected; full repo coverage needs the L2 aggregate
that the next story lands).
CI integration deferred to the L2 aggregate story (the merged
coverage/lcov.info this script reads doesn't exist yet — pnpm
coverage:aggregate produces it).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
