Add tests for the deprecation middleware Sunset and Link header emission

[mikewheeleer]

Test the deprecation header middleware

Description

The deprecation middleware in src/middleware/deprecation.js implements RFC 8594 by setting Deprecation: true, an optional Sunset header (parsed from an ISO-8601 string, silently skipped when unparseable), and an optional Link header pointing at migration docs. It is used to mark legacy unversioned routes ahead of the /v1 namespace, yet there is no dedicated test asserting the exact header values and the skip-on-invalid-date behavior. This issue adds comprehensive coverage of the middleware's header contract.

Requirements and context

• Repository scope: Liquifact/Liquifact-backend only.
• Assert Deprecation: true is always set, that a valid sunset produces a correctly-formatted Sunset UTC header, and that an invalid/unparseable sunset is silently omitted (no malformed header).
• Assert the Link header is <url>; rel="deprecation" when link is provided and absent otherwise.
• Cover the no-options case (only Deprecation set) and confirm next() is always called.
• Keep the tests pure middleware-level; no production change unless a real gap surfaces.

Suggested execution

• Fork the repo and create a branch
• git checkout -b test/deprecation-10-header-coverage
• Implement changes
  • Write code in: test-only changes unless a real header bug surfaces.
  • Write comprehensive tests in: src/__tests__/deprecation.test.js.
  • Add documentation: summarize the header contract in the PR description.
  • Add comments on the date fixtures.
  • Validate security: no caller-controlled value is reflected unescaped into a header.
• Test and commit

Test and commit

• Run npm test and npm run lint.
• Cover edge cases: valid sunset, invalid sunset, link present/absent, no options, next always called.
• Include the full npm test output and a short notes section in the PR description.

Example commit message

test(deprecation): cover Sunset/Link header emission and invalid-date skip

Guidelines

• Minimum 95 percent test coverage for impacted modules.
• Clear, reviewer-focused documentation.
• Timeframe: 96 hours.

Community & contribution rewards

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[silentgeckoaudit3801]

Hi maintainers, I would like to work on this if it is still available.

I can keep the change test-only and focused on the middleware contract: Deprecation: true, valid UTC Sunset, invalid sunset omission, optional Link: <url>; rel="deprecation", no-options behavior, and next() being called in each path.

I will wait for assignment or maintainer confirmation before opening a PR.

[YfengJ]

Hi maintainers, I'd like to take this if it is still available. I would keep the scope test-only around the deprecation middleware contract: Deprecation always set, valid Sunset formatting, invalid Sunset omission, optional Link rel="deprecation", no-options behavior, and next() being called, without changing production behavior unless the tests expose a real gap.