[vite-plugin] Fix flaky WebSocket upgrade test and harden upgrade handler

[petebacondarwin]

Deflakes the @cloudflare/vite-plugin WebSocket upgrade test on Windows CI, and fixes a latent unhandled-rejection bug it exposed.

Observed flake: Tests (Windows, packages-and-tools) — handleWebSocket > does not forward framing headers from the Worker response:

• AssertionError: expected '' to contain 'HTTP/1.1 101'
• Error: Hook timed out in 10000ms (afterEach)
• MiniflareCoreError [ERR_DISPOSED] unhandled rejection

Root cause: listen() never awaited miniflare.ready, so a cold workerd boot was charged against vi.waitFor's 1s default timeout instead of the 50s test timeout. On the contended Windows runner the boot exceeded 1s, so no bytes arrived. The test then threw before its socket.destroy(), so httpServer.close() hung on the live socket — and because this package's vitest config didn't extend the shared one, hookTimeout fell back to the 10s default (and there was no retry safety net). Finally, afterEach's dispose() rejected the still-pending dispatchFetch, and the async upgrade handler had no try/catch, surfacing the ERR_DISPOSED unhandled rejection.

Changes:

• src/websockets.ts (real fix): wrap the upgrade handler in try/catch and destroy the socket on failure. Without this, a rejected dispatchFetch during dev-server shutdown/restart escapes the async listener as an unhandled rejection (can terminate the process) and leaks the client socket. This path is reachable in real vite dev/vite preview, not just tests.
• src/__tests__/websockets.spec.ts: listen() awaits miniflare.ready (deterministic fix); Miniflare created per-test via a helper (no throwaway spawn); afterEach tears down tracked sockets and calls closeAllConnections() before closing the server so a failed assertion can't cascade into a hook timeout; explicit { timeout: 10_000 } on the two real round-trip waits; added a regression test asserting no unhandled rejection when dispatchFetch fails.
• vitest.config.ts: extend vitest.shared.ts to inherit retry: 1, hookTimeout/teardownTimeout, etc.

Verification: websockets.spec.ts 9/9 pass; full package suite 179/179 across 18 files (confirms restoreMocks: true from the shared config regresses nothing); type-check, lint, and format clean. Removing the try/catch makes the new regression test hang the process, confirming it catches the bug.

---

• Tests
  • Tests included/updated
  • Automated tests not possible - manual testing has been completed as follows:
  • Additional testing not necessary because:
• Public documentation
  • Cloudflare docs PR(s):
  • Documentation not necessary because: internal test/robustness fix with no user-facing API or behavior change.

Note

This is a contribution from an AI agent: OpenCode, anthropic/claude-opus-4-8.

---

[changeset-bot]

🦋 Changeset detected

Latest commit: b7b386c

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@cloudflare/vite-plugin	Patch

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[workers-devprod]

Codeowners approval required for this PR:

• ✅ @cloudflare/wrangler

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[github-actions]

✅ All changesets look good

[ask-bonk]

Review submitted successfully to PR #14862.

Summary of my review:

• Production fix (websockets.ts): Correct. Wrapping the async upgrade handler in try/catch, destroying the socket, and cleaning up the WeakMap entry properly addresses the unhandled-rejection-on-shutdown bug.
• Config/test refactor: Sound — extending vitest.shared.ts, awaiting mf.ready, and tracked-socket teardown in afterEach are all reasonable deflaking measures.
• One actionable issue (low severity): Posted an inline suggestion recommending onTestFinished to guarantee cleanup of the global unhandledRejection listener, since the current process.off only runs on the success path and would leak on a hang/timeout (compounded by retry: 1).

github run

[devin-ai-integration]

✅ Devin Review: No Issues Found

Devin Review analyzed this PR and found no bugs or issues to report.

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