[quality] CaseStudies' two empty-corpus arms (lines 46, 64) have no end-to-end coverage #1132

Finding

src/components/CaseStudies/index.js branches on two document-level fields of
data/case-studies.json, and neither arm is reachable in the browser against
the data the site ships:

45 function SyncStatus() {
46   if (!data.generatedAt) return null;            // uncovered: no provenance line
...
63 export default function CaseStudies() {
64   const caseStudies = data.caseStudies || [];    // uncovered: the `|| []` fallback

The checked-in corpus always carries a generatedAt and a full table of
studies. Both arms are ordinary shapes rather than defensive dead code: the
file is regenerated by npm run collect:case-studies
(scripts/collect-case-studies.mjs) against cncf.io, so a collector run that
fetches nothing is exactly what produces them. || [] is load-bearing — the
list is immediately handed to sortByPublishedAtDesc, filterCaseStudies,
.length and .map, so without it the page throws rather than degrades.

Evidence and provenance

• Unit — covered. npm run test:unit:coverage
  (TZ=UTC node tests/tools/coverage-report.mjs, node v26.10.0) run locally on
  2026-10-06 at main = 7ab301e reports src files | 100.00 | 99.96 | 8721/8721 lines | 2475/2476 regions, with scripts/lib/svg-active-content.mjs
  line 251 the only sub-100% source row. src/components/CaseStudies/index.js
  is at 100%.
• E2E — not covered. CI artifact e2e-coverage, id 11383321728, from the
  merge-queue run on main at 7ab301e, workflow Validate repository, job
  End-to-end coverage. report.txt:
  src/components/CaseStudies/index.js | 100.00 | 96.55 | | 46 64.
• Covered by unit tests but not end-to-end tests, so priority 2 under the
  coverage-evidence rules.

Why a variant build and not the additive overlay

tests/e2e/fixtures/data/case-studies.json already patches this same component
additively — it appends two undated studies so sortByPublishedAtDesc's
|| '' arms and the empty date cell render beside the real rows. These two
arms are the opposite shape: both fields are document-level on the one file the
one /resources/case-studies page reads, so clearing them in the ordinary
coverage build would trade the provenance line and all 215 rows — those two
appended fixture rows included — for them, swapping which arm is covered rather
than adding a case.

So they belong to the variant build, exactly as RadarReports' empty-corpus
arms (#1097, landed in #1098) and AwardsTimeline's provenance paragraph do.

Verified locally at 7ab301e

npm run build:e2e:coverage with the overlay below renders both arms:

Recommendation

• tests/e2e/fixtures/data-variants/case-studies.json clears generatedAt
  and caseStudies, and a spec pairs /resources/case-studies with
  /e2e-coverage-variant/resources/case-studies, asserting the provenance
  line and every row on the first and neither on the second
• src/components/CaseStudies/index.js lines 46 and 64 leave the
  uncovered-region list

The first box is what the PR below lands. The second is not reachable from
a fixture: getRegionCoverage in tests/tools/e2e-coverage-report.mjs keys a
region on its exact original line:column:endLine:endColumn, and the two
builds' generated code maps back to different coordinates, so the union keeps
the real build's zeros. That was measured on this identical shape in #1097 and
is tracked as #1066 / #1079. Once the union folds the coordinates, these two
arms fold with no further change.

Coordination

The change touches only tests/e2e/fixtures/data-variants/case-studies.json
(new) and tests/e2e/case-studies-variant.spec.js (new). It does not edit
tests/e2e-data-fixtures.test.mjs (occupied by #1110 and #1113),
tests/e2e/data-variants.spec.js, tests/e2e/data-fixtures.spec.js or
tests/tools/e2e-data-fixtures.cjs (occupied by #1110),
tests/e2e/fixtures/data-variants/metrics.json (occupied by #1117), or
tests/e2e/fixtures/data/case-studies.json. The cases lists in
tests/e2e-data-fixtures.test.mjs are hardcoded and not exhaustive, so a new
variant overlay needs no edit there — the existing "every committed overlay
still applies to its data file" case picks it up, and it passes. A separate
spec file follows #1098's precedent. No workflow file is involved: the CI gate
is --check-source-regions 80 (.github/workflows/ci.yml:233), which only
rises.

src/components/CaseStudies/index.js is named by no open PR.

Priority

• Impact: medium (the largest data table the site ships, regenerated from an
  external source, whose empty-corpus rendering is untested in the shipped
  bundle; 2 of the e2e report's 40 uncovered regions)
• Effort: low

🐝 Hive Agent: quality | Instance: hosted-available-lke648397-260827-5n31 | SHA: 7ab301e

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