charlie: vitest

[shellscape]

The goal of this issue is to migrate all Ava tests in the repository to Vitest.

Phase 1 — low-complexity packages (mechanical conversions)

• packages/beep
• packages/buble
• packages/data-uri
• packages/dsv
• packages/eslint
• packages/graphql
• packages/image
• packages/inject
• packages/legacy
• packages/multi-entry
• packages/strip
• packages/sucrase
• packages/swc
• packages/virtual
• packages/yaml

Phase 2 — medium complexity (snapshot/serial heavy)

• packages/babel
• packages/dynamic-import-vars
• packages/esm-shim
• packages/html
• packages/json
• packages/replace
• packages/terser
• packages/url
• packages/wasm

Phase 3 — medium complexity (environment/lifecycle sensitive)

• packages/auto-install
• packages/pluginutils
• packages/run

Phase 4 — high complexity (largest fixture matrices)

• packages/node-resolve
• packages/commonjs
• packages/typescript

Constraints for each phase

1. Perform a straight Ava → Vitest migration only (no compatibility layer).
2. Convert tests/assertions file-by-file, replacing Ava patterns/builtins with Vitest patterns/builtins.
3. Do not modify test logic or the shape/intent of what is being tested.
4. Keep changes succinct and clean (no over-engineered supporting abstractions).
5. Update repository configuration as needed during migration (including root package.json and package-level test config/scripts where required).
6. Before PR readiness, inspect .github/workflows and run all required checks; CI must be passing.
7. Fix any migration-introduced failures before considering the work mergable.
8. This plan intentionally avoids the previously closed approach from chore(repo): migration from ava to vitest. phase 1 #1972.
9. Treat packages/alias as canonical template.
10. Lock a single Vitest invocation pattern per package (using .config/vitest.config.mts).
11. Confirm snapshot path parity and CI behavior before batch migrations.
12. This repository uses conventional commit format. Each commit should be in that format. The PR title for each phase should be in the format chore(repo): test migration to vitest. phase {phaseNumber}
13. If you think you have to add dependencies at any point, push what you have, open the PR, and ask questions about adding the dependency(s) before doing so

[shellscape]

@CharlieHelps please open a new PR for Phase 1

[charliecreates]

Opened a new PR for Phase 1: #1975

It migrates the 15 Phase 1 packages from Ava → Vitest using packages/alias as the template, including package script updates, Vitest assertion/API conversion, shared Vitest config alignment, and snapshot migration updates.

Validation was run across all Phase 1 package tests (plus test:ts where present) before opening the PR.

[shellscape]

@CharlieHelps #1975 has been merged and phase 1 is complete. Please re-read the spec #1974 (comment) and open a PR for phase 2.

[charliecreates]

Phase 2 is ready in #1976.

I re-read the spec and migrated these packages from Ava to Vitest in this phase:

• packages/babel
• packages/dynamic-import-vars
• packages/esm-shim
• packages/html
• packages/json
• packages/replace
• packages/terser
• packages/url
• packages/wasm

I also updated shared/test config where needed for the phase-2 file patterns and ran local verification:

• phase-2 package ci:test checks
• pnpm lint:js
• pnpm prettier:check

All passed locally.

[shellscape]

@CharlieHelps #1976 has been merged and phase 2 is complete. Please re-read the spec #1974 (comment) and open a PR for phase 3.

[charliecreates]

@shellscape Phase 3 is ready in #1977.

Migrated packages:

• packages/auto-install
• packages/pluginutils
• packages/run

Checks passed for the phase-3 package tests/coverage and repo lint/prettier checks.