# Contributing

Thanks for taking a look.

## Getting set up

```bash
npm install
npm run check    # typecheck + lint + format + tests + build
```

`npm run format` rewrites files to match Prettier; `npm run lint` is ESLint on
its own. Markdown is left to hand-wrapping — see `.prettierignore`.

Tests use the Node built-in runner (`node:test`), compiled with `tsc` first —
there is no test framework to install. Sources are in `src/`, tests in `test/`.

## Ground rules

- **A behaviour change comes with a test.** A fake should not be enabled by
  accident, so every rule in the README's behaviour table has a test pinning
  it.
- **Keep the per-resolution path cheap.** Metro calls the returned resolver
  for every module in the graph. Anything expensive belongs in
  `createSliceResolver`, which runs once.
- **No runtime dependencies.** The package must stay installable into any
  Metro project without pulling a tree behind it.
- **Fail loudly when the resolver is built**, rather than quietly at resolve
  time. A misconfiguration that leaves you on the real module while you think
  you are on a fake is hard to spot.

## Releasing

1. Update `CHANGELOG.md` under a new version heading.
2. `npm version <patch|minor|major>` — `prepublishOnly` runs `npm run check`.
3. `npm publish && git push --follow-tags`.