agentinit / rules

---
description: Testing conventions (unit tests, fixtures, snapshots, end-to-end runs)
globs: tests/**/*.ts
alwaysApply: false
---

# Tests

- Unit tests mirror `src/` (`src/registry/resolve.ts` → `tests/registry/resolve.test.ts`); end-to-end tests live in `tests/e2e/`.
- PREFER table-driven tests (`it.each`) for pure modules; name each case after the behavior it proves.
- ALWAYS run filesystem tests in a temp directory (`fs.mkdtemp`) and clean up; NEVER write inside the repo or a fixture.
- End-to-end tests copy a fixture to a temp dir and call `run([...args, '--cwd', dir])`; NEVER spawn the CLI unless the test is about the binary itself.
- ALWAYS snapshot generated files with `toMatchFileSnapshot` so diffs are reviewable; NEVER update snapshots without reviewing the diff.
- Fixtures are minimal but realistic; fake installed packages go in `tests/fixtures/<name>/node_modules/<pkg>/package.json` (committed on purpose).
- Inject time and prompts (fake `Prompter`) instead of mocking globals.
- NEVER make network calls in tests.

```ts
// ✅ Good: isolated, behavior-named, temp dir
it('keeps user content outside managed blocks byte-for-byte', async () => {
  const dir = await copyFixture('existing-claude-md');
  await run(['init', '--yes', '--cwd', dir]);
  expect(await readUserSection(dir)).toBe(original);
});

// ❌ Anti-pattern: runs in the fixture itself and mutates it
await run(['init', '--yes', '--cwd', 'tests/fixtures/existing-claude-md']);
```