# Testing Strategy

## Test Layers

| Layer | Tool | What to Test |
|---|---|---|
| Entities | Vitest (unit) | Zod schema validation, error classes |
| Use Cases | Vitest (unit) | Business logic with mock implementations via DI |
| Controllers | Vitest (unit) | Input validation, use case delegation, error mapping |
| Infrastructure | Vitest (integration) | Real DB via test containers, Payload API calls |
| UI Components | Vitest + Storybook | Rendering, props, accessibility |
| Full App | Playwright (E2E) | User flows across both Next.js and TanStack Start |

## Running Tests

```bash
pnpm test                              # All tests via Turborepo
cd packages/core && pnpm vitest run    # Core unit tests only
cd packages/core && pnpm vitest watch  # Core tests in watch mode
```

## Test Pattern (DI Container)

All tests that use the DI container must initialize and destroy it:

```typescript
import "reflect-metadata";
import { beforeEach, afterEach } from "vitest";
import { initializeContainer, destroyContainer } from "@/di/container.js";

beforeEach(() => { initializeContainer(); });
afterEach(() => { destroyContainer(); });
```

This ensures each test gets fresh mock instances (singleton scope resets).

## Test File Location

- Core tests: `packages/core/tests/unit/{use-cases,controllers}/{domain}/`
- UI tests: co-located next to component (`*.test.tsx`)
- E2E tests: `tests/e2e/`