[duongynhi000005-oss]

Closes #261

Summary

Adds comprehensive unit and integration API test coverage across backend route handlers along with automated 80%+ coverage threshold enforcement and baseline/target documentation.

Changes

• Comprehensive Route Handler Suite (backend/tests/routes/comprehensiveRoutes.test.ts):
  • Covers verify.ts (/api/v1/verify), disputes.ts (/api/disputes), metrics.ts (/api/metrics), forum.ts (/api/forum), notifications.ts (/api/notifications), progress.ts (/api/progress), classroom.ts (/api/classroom), bookmarks.js (/api/bookmarks), localization.ts (/api/localization), and vrf.ts (/api/vrf).
  • Exercises 200/201 success paths, 400 validation & bad-request errors, 401/403 authentication & RBAC checks (authenticate, optionalAuth, requireAdmin, host-only checks, internal metrics key), 404 resource not found errors, and 500 internal server error propagation through the RFC 7807 errorHandler.
• Auth Middleware Parity (backend/src/middleware/auth.js):
  • Exports optionalAuth and authMiddleware in src/middleware/auth.js so CommonJS/Jest module resolution matches src/middleware/auth.ts.
• Coverage Configuration & Documentation (backend/jest.routes.config.js, backend/package.json, backend/docs/API_TEST_COVERAGE.md):
  • Adds
    pm run test:routes:coverage enforcing >= 80% statements, branches, functions, and lines.
  • Documents baseline vs achieved coverage (98.94% statements, 88.63% branches, 100% functions, 98.89% lines).

Verification

pm --prefix backend run test:routes:coverage: 2 passed suites, 45 passed tests (98.94% statements, 88.63% branches, 100% functions, 98.89% lines).