Versioning module has no tests: version negotiation and compatibility transforms are uncovered

[nanaf6203-bit]

Versioning module has no tests: version negotiation and compatibility transforms are uncovered

Labels / Complexity: testing · Medium Complexity — Medium

Problem

src/versioning/ (12 files, 0 *.spec.ts) implements the API versioning machinery every versioned endpoint depends on — header negotiation, deprecation warnings, and backward-compatibility.service.ts's per-version response transforms. None of it is pinned by tests: a regression that mis-negotiates a version or drops a compatibility transform ships silently, serving wrong-shaped responses to older clients.

Why this is architecturally hard

1. Transform logic is the test design. Compatibility transforms reshape responses per version; tests need fixtures showing the same payload through each version boundary.
2. Header negotiation is cross-cutting. Version-header parsing must be exercised through HTTP-level tests to cover missing, invalid, and conflicting version headers.

Acceptance criteria

• Tests cover version-header parsing (valid, missing, invalid), deprecation warnings, and at least one compatibility transform.
• Tests run in CI via npm test.
• The PR reports the module's coverage change (npm run test:cov).

Out of scope

Changing versioning behavior; the @ts-nocheck migration for the module (tracked separately).

Getting started

• src/versioning/backward-compatibility.service.ts — the transforms
• src/versioning/version-header.interceptor.ts — the negotiation

Commands: npm test, npm run test:cov.

Good first files to read: src/versioning/backward-compatibility.service.ts, src/versioning/version-header.interceptor.ts.