Four independent cuts into the 2-4 hour full run, none touching the contract
"a mutant must turn its guard red":
- guardNeedsBundle: rollup runs only for guards that open the built bundle
(demo/ smokes, golden captures, bundle:sync) — 68 of 253 registry entries.
Unit and backend guards never read dist/ as a build artifact (verified
against every test that mentions dist/**: they read the git checkout or
synthetic files), so 185 mutants skip the most expensive step entirely.
- seedTestBuild + incremental tsc: the mutant worktree starts from the main
tree's warm test-build/ and .tsbuildinfo; tsc compares file hashes, not
mtimes, so the fresh checkout stays warm and only the mutated delta is
recompiled. This also speeds up the long guards that run tsc themselves.
- --changed[=range]: run only mutants whose patch files are touched by the
diff (origin/dev..HEAD by default). An empty selection is an honest success
with an explicit message — the full registry remains the pre-release
contract, per the workflow comment.
- --shard=i/n: deterministic interleaved slices; the workflow runs a 4-way
matrix, and a warm test-build step feeds every shard. Interleaving spreads
the expensive browser mutants across shards instead of clumping them.
Measured per mutant on this machine: unit 12-13 s (was ~50-70 s), backend
6 s, browser 32 s (unchanged — the bundle is genuinely needed there). Full
run estimate drops to ~70 sequential minutes, ~20 on four shards.
Unit coverage: guard classification on real registry shapes, a floor on both
classes so the split cannot silently collapse, changed-selection semantics,
and shard completeness/disjointness with an anti-clumping bound.
Issue: #332
User-Visible: no
The reviewer is right twice over. My previous commit fixed the red CI by
relaxing the contract — a guard could name a `.py` file — when the registry
already had a convention for exactly this case: every backend mutant runs
`node scripts/backend-test-guard.mjs <pattern> <file>`, which owns the python
executable choice and the `-k` selection. Bending a rule to fit my one-off is
the worse of the two possible fixes, so the contract goes back to demanding a
`.mjs` guard, and junction-limit-backend-raw-baseline now uses the helper and
targets the one test that proves the migration
(test_legacy_baseline_is_judged_after_the_same_migration).
Re-verified: registry --check clean, the mutant still catches its regression
1/1, npm test 1390 passed / 0 failed.
Issue: #329
User-Visible: no
The registry contract demanded that every guard name a `.mjs` file, which was
true until this task added the first backend mutant —
junction-limit-backend-raw-baseline is guarded by pytest, and the mutation-gate
job already installs it. My mistake: I ran `--check` and the single mutant
after adding it, but not the unit suite that owns the registry contract, so CI
caught what I should have.
The contract keeps its point: a guard must name a file that exists.
Issue: #329
User-Visible: no
Five times in this project a green test meant nothing was checked. The
continuity smoke stayed green after the entire mechanism it guards was cut out.
The golden scene created to protect doorway light was empty — 1,177 warm pixels
against 107,119, all of them icons. The shadow smoke passed while no shadow was
drawn. Each time the test had been written alongside the code, went green at
once, and nobody ever asked whether it could go red.
The gate makes that question routine. Each mutant is a few lines of patch that
reproduce a known breakage, plus the name of the test that must fail on it. A
worktree is patched, the bundle rebuilt, the guard run — and a guard that stays
green fails the gate. Six mutants cover the holes documented in #85; the anchors
are exact strings from today's source, so the registry cannot silently drift —
a unit test that runs with the ordinary suite refuses a stale anchor.
The full run rebuilds the bundle per mutant, so it lives in its own workflow,
before a stable release and on a weekly schedule, not in Validate. The rules for
new tests are written at the top of docs/TESTING.md, and the sixth of them is
the cheapest: an assertion that reads back the property the code just set is
not written at all.
Issue: #85
User-Visible: no
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