[quality] parseProwConfig's empty-document arm (config.ts:373, return {}) has no end-to-end coverage through dist/index.js #394

Finding

The empty-document arm of parseProwConfig — src/utils/config.ts:373, return {} when the loaded yaml is undefined/null — is never exercised by the bundle test suite, although it is the arm every blank or placeholder prow.yaml takes.

Evidence (main @ aa6a0f8, Node v26.10.0, vitest 5.0.3):

• Unit: npx vitest run --coverage → 100 % lines of src/. The arm is reached by __tests__/utils/config.test.ts:420-426 (treats %s as an all-empty config: '', '---\n', ' \n').
• End-to-end: npm run test:coverage:e2e on a scratch branch = origin/main + the heads of all 35 open hold-gated bundle PRs (test(bundle): drive root-OWNERS authorization on an issue and the OWNERS-based /lgtm refusal through dist/index.js #283 … test(bundle): drive the lgtm job's no-lgtm-label arm (onPrLgtm.ts:33) and label-sync's verbatim labels.labels allowlist (labelCatalog.ts:80) through dist/index.js #392, all merge clean; 56 files / 426 tests pass) → 97.76 % lines of src/; config.ts residual is 220,373,427. Line 220 is the test-only resetProwConfigCache; 373 has 0 hits; 427 is the normalizeSections map callback, whose 0 hits are inconsistent with the /kind and /lifecycle bundle runs that build sections from a file, so it is not claimed here (likely a source-map remap artifact, left for a separate look).
• Reachability from the bundle: loadRepoTier returns the first repository path that exists, so a blank .github/prow.yaml is a found source (config.sources.length === 1) and getLabelConfig does not raise no prow configuration found; /lifecycle stale then serves Prow's built-in frozen,stale,rotten and /kind cleanup fails with kind: yaml malformed, expected 'kind' top level key. Neither behaviour is asserted anywhere under __tests__/bundle/: labelCommands.test.ts covers the built-in defaults only via a .prowlabels.yaml that lacks the key, and the no-file failure.

Not claimed by #314 (explicit config source), #339 (schema rejections), #366 or #386.

Recommendation

• add __tests__/bundle/emptyConfigDocument.test.ts: route GET /repos/Codertocat/Hello-World/contents/.github%2Fprow.yaml with a blank body and with ---\n, drive /lifecycle stale (exit 0, lifecycle: using built-in labels frozen,stale,rotten, one POST /issues/1/labels with lifecycle/stale, config reads stop at .github/prow.yaml) and /kind cleanup (exit 1, kind: yaml malformed, expected 'kind' top level key, no no prow configuration found, no label write)

A comment-only file belongs in the same table but currently throws YAMLException: expected a document, but the input is empty through the bundle; that is a production defect filed separately, and the test leaves that row out until it is fixed.

Priority

• Impact: medium (unit-covered, no end-to-end coverage)
• Effort: low

🐝 Hive Agent: quality | Instance: hosted-available-lke648397-260827-5q9t | SHA: aa6a0f8

— hive: agent=quality backend=copilot model=claude-fable-5.1 copilot=1.0.88