test(etag): add test coverage for pairs-list ETag and 304 conditional…

[Unclebaffa]

Summary of Changes

Added comprehensive test coverage for the GET /api/v1/pairs weak ETag and 304 Not Modified conditional response behavior in src/__tests__/etag.test.ts:

1. Initial GET response:
   • Asserted that GET /api/v1/pairs returns status 200 with a weak ETag header (W/"...").
   • Asserted that the 200 body is valid JSON containing the pairs array.
2. Conditional GET with matching If-None-Match:
   • Captured the weak ETag from the initial response header and reused it in a follow-up request with If-None-Match.
   • Asserted that the server returns 304 Not Modified with an empty body (text === "" and no JSON payload).
3. GET without If-None-Match header:
   • Verified requests without If-None-Match return 200 with full body and ETag header.
4. ETag invalidation on pair registration & unregistration:
   • Asserted that registering a pair updates the ETag and causes a request with a stale If-None-Match to return 200 with the new pair included.
   • Asserted that unregistering (deleting) a pair updates the ETag and causes a request with a stale If-None-Match to return 200 with the pair omitted.
5. HEAD /api/v1/pairs coverage:
   • Asserted matching If-None-Match on HEAD returns 304 with empty body.
   • Asserted non-matching If-None-Match on HEAD returns 200 with empty body, Content-Length, Content-Type, and ETag headers matching GET.

---

Build and Test Verification

1. TypeScript Build (npm run build)

> stableroute-backend@0.1.0 build
> tsc

Build finished with 0 errors.

2. ESLint (npm run lint)

> stableroute-backend@0.1.0 lint
> eslint src

✖ 12 problems (0 errors, 12 warnings)

Lint finished with 0 errors.

3. Test Suite (npm test)

PASS src/__tests__/errorHandler.test.ts
PASS src/__tests__/durablePause.test.ts
PASS src/__tests__/apiKeyScopes.test.ts
PASS src/__tests__/config.test.ts
PASS src/__tests__/rateLimit.test.ts
PASS src/__tests__/pairsBulk.test.ts
PASS src/__tests__/metricsStoreGauges.test.ts
PASS src/__tests__/healthDeep.test.ts
PASS src/__tests__/webhooks.test.ts
PASS src/__tests__/server.test.ts
PASS src/__tests__/bulkQuote.test.ts
PASS src/__tests__/etag.test.ts
PASS src/__tests__/apiKeys.test.ts
PASS src/__tests__/events.test.ts
PASS src/__tests__/fallback404.test.ts
PASS src/__tests__/pauseGuard.test.ts
PASS src/__tests__/statsBreakdown.test.ts
PASS src/__tests__/auditLifecycle.test.ts
PASS src/__tests__/pairReadDelete.test.ts
PASS src/__tests__/persistence.test.ts
PASS src/__tests__/openapi-smoke.test.ts
PASS src/__tests__/stores.test.ts
PASS src/__tests__/index.test.ts
PASS src/__tests__/openapi.test.ts
PASS src/__tests__/cors.test.ts
PASS src/__tests__/pairsEtag.test.ts
PASS src/__tests__/parseAmountAssetCode.test.ts
PASS src/__tests__/readOnlyMode.test.ts
PASS src/__tests__/logger.test.ts
PASS src/__tests__/version.test.ts
PASS src/__tests__/utils.test.ts
PASS src/__tests__/pairMetaEnabled.test.ts
PASS src/__tests__/pricing.test.ts
PASS src/__tests__/securityHeaders.test.ts
PASS src/__tests__/store.adapter.test.ts

Test Suites: 35 passed, 35 total
Tests:       862 passed, 862 total
Snapshots:   0 total
Time:        19.826 s

4. Coverage Summary (npm run test:coverage)

File             | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s
-----------------|---------|----------|---------|---------|-------------------
All files        |   93.43 |    87.22 |   95.38 |   93.65 |
 src             |   93.04 |    86.67 |   95.19 |   93.33 |
  index.ts       |   90.97 |    84.59 |   94.48 |   91.41 | ...
  logger.ts      |     100 |      100 |     100 |     100 |
  openapi.ts     |     100 |      100 |     100 |     100 |
  pauseState.ts  |   96.15 |       90 |     100 |   95.65 |
  persistence.ts |   98.57 |    96.55 |     100 |     100 |
  pricing.ts     |     100 |      100 |     100 |     100 |
  server.ts      |   96.73 |    94.59 |   95.83 |   97.59 |
  stores.ts      |   97.15 |     90.9 |   94.11 |    96.7 |
 src/store       |   95.65 |    84.61 |      96 |   95.49 |
 src/utils       |     100 |      100 |     100 |     100 |
-----------------|---------|----------|---------|---------|-------------------
Test Suites: 35 passed, 35 total
Tests:       862 passed, 862 total

Closes #282

[mikewheeleer]

solid — thanks for picking it up 🙌