Test the 406 fallback in @fedify/express

[co2plant]

Resolves #858.

Summary

@fedify/express uses onNotAcceptable to let Express try HTML routes before falling back to a 406, which is what keeps an actor and its HTML profile page shareable on one URL. The fallback branch—no route matched, so the middleware sends the 406 itself—had no test.

This adds a test in packages/express/src/index.test.ts that drives integrateFederation() with a mock federation calling onNotAcceptable(), and asserts the response status is 406.

Tests

• mise run test:deno packages/express/src/index.test.ts
• mise run check-each express

AI disclosure

Assisted-by: Claude Code:claude-opus 4.8

This change was written with assistance from Claude Code (claude-opus-4-8), reviewed and verified by me.

[netlify]

✅ Deploy Preview for fedify-json-schema canceled.

Name	Link
🔨 Latest commit	f27d436
🔍 Latest deploy log	https://app.netlify.com/projects/fedify-json-schema/deploys/6a8466b406b2e900083a3da0

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: ASSERTIVE

Plan: Pro Plus

Run ID: caa80aa0-8038-44a3-b4f3-18c0f78b69a3

📥 Commits

Reviewing files that changed from the base of the PR and between bf6d525 and f27d436.

📒 Files selected for processing (1)

• packages/express/src/index.test.ts

Included review availability: Your plan includes up to 4 reviews per rolling hour; 3 remain after this review.

---

📝 Walkthrough

Walkthrough

Changes

Express not-acceptable handling

Layer / File(s)	Summary
406 fallback regression test packages/express/src/index.test.ts	Adds an integration test for the onNotAcceptable callback. The test verifies a 406 response when no Express route handles the request.

Estimated code review effort: 2 (Simple) | ~10 minutes

Merge Risk: ⚪ Minimal · up to f27d4

This change adds coverage for the Express 406 fallback without changing production behavior. No actionable merge-blocking risk remains beyond normal checks and review.

Suggested reviewers: 2chanhaeng, dahlia

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly identifies the 406 fallback test in @fedify/express.
Description check	✅ Passed	The description accurately explains the regression test, its purpose, and the related validation commands.
Linked Issues check	✅ Passed	The test covers onNotAcceptable with no matching Express route and verifies the 406 fallback required by issue #858.
Out of Scope Changes check	✅ Passed	The changes add only the regression test described in issue #858 and the pull request objectives.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ All tests successful. No failed tests found.
see 1 file with indirect coverage changes

🚀 New features to boost your workflow:

• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[dahlia]

Thanks for your contribution!