fix-vi-flaky-test

Fix a flaky test in vercel-internal

You were asked to fix one flaky test from test.yml, or to add diagnostics for a shard hang. Your instructions list the attempts that failed and then passed on rerun, their branches, and log lines. code-change covers publishing; this skill covers this repository's tests.

A test seen on one branch may be that pull request's own problem: check whether the pull request changed the failing test or what it tests (git log on the pinned commit, or the run's PR). If it did, finish without a change and say so.

Set up the sandbox

The sandbox has Node and pnpm but no C compiler or Rust, and part of the build needs both. Its Linux varies (Ubuntu with apt-get, or Amazon Linux with dnf). Run these once, from the workspace root (about four minutes in all):

if command -v apt-get >/dev/null; then sudo apt-get update -qq && sudo apt-get install -y -qq gcc libc6-dev; else sudo dnf install -y -q gcc; fi
curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y -q --profile minimal --default-toolchain 1.96.1 --target wasm32-wasip2

Then install dependencies with install_dependencies and filter vercel..., and build what the CLI's tests import:

. "$HOME/.cargo/env"
cd repo/packages/python-analysis && pnpm run build:wasm && cd ../..
pnpm --filter "vercel^..." run build

Use pnpm --filter, not turbo: Turbo also needs Cargo just to read the task graph. For a test in another package, build "<package>^..." instead.

Run the test

• One CLI unit test file: cd repo/packages/cli && node ./scripts/test.mjs --run --retry=0 <file>.
• One CLI Unit shard, the same files as CLI Unit / … / 6/7: VITEST_SHARD=6/7 node ./scripts/test.mjs --run --retry=0 test/unit/ (about two minutes).
• Vitest retries every failed test three times in this repository. Always pass --retry=0 when reproducing, and run the test or shard several times; a flaky test usually passes once.

A hang: [test] chunk timed out after 1200s