Personal-AI-Router / rules

---
description: Type-safe modular test patterns and isolation requirements
globs: tests/**/*.{ts,tsx}
alwaysApply: false
---
<!--
SPDX-FileCopyrightText: Copyright (c) 2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
SPDX-License-Identifier: Apache-2.0
-->

# Test Discipline

Tests follow the same type and import rules as production code:

- no type casts, `any`, or `unknown` data shapes;
- static imports only;
- `@/...` for cross-directory source imports;
- real shared contract types instead of test-specific copies.

## Typed mocks

Parameterize `vi.fn` with the function type being replaced.

```ts
const invoke = vi.fn<PreloadServiceTransport['invoke']>()
```

Use `vi.mocked(realFunction)` for configured module mocks and call assertions.
Reusable fakes implement the production interface they replace.

## Fixtures

- Use typed `.ts` fixtures.
- Prefer `satisfies` for object-shape validation.
- Keep reusable filesystem isolation in `tests/fixtures/tmpdir.ts`.
- Keep process and network isolation in `tests/fixtures/isolation.ts`.

## Side effects

Mock process, filesystem, network, registry, and Electron boundaries in the test
runtime. Do not add test-only branches or environment flags to production code.

`PAIR_USER_DATA` is the supported runtime override used by tests to isolate
application data. Do not add `PAIR_TEST_DISABLE_*` switches.

## Verification

Tests are part of `npm run typecheck` through `tsconfig.test.json`. Run the
targeted Vitest project and `npm run typecheck` after changing test contracts.