# Testing Patterns

**Analysis Date:** 2026-06-09

## Test Framework

**Runner:**

- Backend: Vitest 4.1.8, Node environment
- Frontend: Vitest 4.1.8, jsdom environment
- Config: `apps/api/vitest.config.ts`, `apps/pwa/vitest.config.ts`

**Assertion Library:**

- Vitest built-in `expect()`
- Testing Library (`@testing-library/react`, `@testing-library/jest-dom`) for component DOM assertions
- `jest-dom` matchers extended via `apps/pwa/src/test-setup.ts`

**Run Commands:**

```bash
# Run all tests
pnpm test

# Run tests in watch mode
pnpm --filter @familysync/api test:watch
pnpm --filter @familysync/pwa test:watch

# Run with coverage (not configured yet)
vitest run --coverage
```

## Test File Organization

**Location:**

- Backend: `apps/api/tests/` parallel to `apps/api/src/` — mirrors source structure
- Frontend: Co-located with source files — `src/components/Foo.tsx` → `src/components/Foo.test.tsx`

**Naming:**

- Test files: `{module}.test.ts` or `.test.tsx`
- Fixtures: `apps/api/tests/fixtures/` — fixture files (e.g., `weekly-dst.ics`) loaded by test helpers

**Structure:**

```
apps/api/tests/
├── health.test.ts                 # End-to-end test for GET /health
├── auth/
│   ├── devBypass.test.ts
│   └── user.test.ts
├── broker/
│   ├── expand.test.ts             # expandOccurrences() unit tests
│   ├── poller.test.ts
│   ├── outboxWorker.test.ts
│   ├── sync.test.ts
│   ├── vevent.test.ts
│   ├── write.test.ts
│   └── crypto.test.ts
├── routes/                        # Route handler tests TBD
├── helpers/                       # Test utility functions
└── fixtures/
    ├── weekly-dst.ics             # DST test fixture (weekly recurrence)
    └── allday-birthday.ics        # All-day recurrence fixture

apps/pwa/src/
├── api/client.test.ts
├── lib/
│   ├── colorUtils.test.ts
│   ├── eventDateTime.test.ts
│   ├── hydrateEvents.test.ts
│   ├── loginRedirect.test.ts
│   └── calendarConfig.test.ts
├── components/
│   ├── InstallPrompt.test.tsx
│   └── ...
└── store/
    └── (Zustand store tested via client.test.ts)
```

## Test Structure

**Suite Organization:**

```typescript
import { describe, it, expect, vi, beforeEach, afterEach } from 'vitest';

describe('GET /health', () => {
  it('returns 200 with { ok: true, db: "up" } when DB round-trip succeeds', async () => {
    // Arrange
    const { app } = await import('../src/index.js');

    // Act
    const res = await app.request('/health');

    // Assert
    expect(res.status).toBe(200);
    const body = (await res.json()) as { ok: boolean; db: string };
    expect(body.ok).toBe(true);
  });

  it('returns 503 when DB round-trip throws', async () => {
    // Arrange
    const { db } = await import('../src/db/client.js');
    vi.mocked(db.execute).mockRejectedValueOnce(new Error('DB connection failed'));

    // Act
    const { app } = await import('../src/index.js');
    const res = await app.request('/health');

    // Assert
    expect(res.status).toBe(503);
  });
});
```

**Patterns:**

- Async test functions with full await chain
- Hono request testing: `app.request(path)` returns a Response object
- Mock setup in `beforeEach`; cleanup in `afterEach` with `vi.unstubAllGlobals()` or `vi.clearAllMocks()`
- Descriptive test names following "should [action] when [condition]" or "[verb] [noun]" pattern
- Arrange-Act-Assert (AAA) comment structure for multi-step tests

## Mocking

**Framework:** Vitest `vi` object (`vi.mock`, `vi.mocked`, `vi.fn`, `vi.stubGlobal`)

**Module Mocking:**

```typescript
// Hoist vi.mock() calls to the top of the module (Vitest requirement)
vi.mock('../src/db/client.js', () => ({
  db: {
    execute: vi.fn().mockResolvedValue([[{ '1': 1 }]]),
  },
}));
```

**Function Mocking:**

```typescript
const mockFetch = vi.mocked(fetch);
mockFetch.mockResolvedValueOnce({
  ok: true,
  json: async () => ({ uid: 'test-uid' }),
} as Response);

// Call the function under test
await createEvent(payload);

// Assert the mock was called correctly
expect(mockFetch).toHaveBeenCalledWith(
  '/api/events/create',
  expect.objectContaining({
    method: 'POST',
    credentials: 'include',
  }),
);
```

**Global Stubs (Frontend):**

```typescript
beforeEach(() => {
  vi.stubGlobal('fetch', vi.fn());
});

afterEach(() => {
  vi.unstubAllGlobals();
});
```

**What to Mock:**

- External I/O: database (via `vi.mock` on `src/db/client.js`)
- Network calls: `fetch` (via `vi.stubGlobal('fetch', ...)`)
- Environment-dependent code: `window.matchMedia` (jsdom polyfill, see test-setup.ts)
- Time-dependent code: `Date`, `setTimeout` (if needed; not used currently)

**What NOT to Mock:**

- Pure utility functions — test them directly (colorUtils, eventDateTime, hydrateEvents)
- Zod validation schemas — test with real payloads
- Zustand stores — instantiate real store, call real methods
- Hono app logic — use `app.request()` to test end-to-end
- iCalendar parsing (ical.js) — test with real .ics fixtures, not mocks

## Fixtures and Factories

**Test Data (Backend):**
Fixture files are `.ics` (iCalendar) strings stored in `apps/api/tests/fixtures/`:

```typescript
// Load fixture file
const rawVevent = readFileSync(join(FIXTURES, 'weekly-dst.ics'), 'utf8');

// Use in test
const occurrences = expandOccurrences(
  rawVevent,
  new Date('2026-03-01T00:00:00Z'),
  new Date('2026-04-01T00:00:00Z'),
  1,
  'My Calendar',
  1,
  'Alice',
  '#4A90D9',
  false,
);
```

**Test Data (Frontend):**
Inline mock objects in test files (no factory pattern needed yet):

```typescript
vi.mocked(fetch).mockResolvedValueOnce({
  ok: true,
  json: async () => ({
    calendars: [
      {
        url: 'https://caldav.fastmail.com/cal1',
        displayName: 'My Calendar',
        color: '#4A90D9',
        isShared: false,
      },
      {
        url: 'https://caldav.fastmail.com/cal2',
        displayName: 'Family',
        color: '#F25C7A',
        isShared: true,
      },
    ],
  }),
} as Response);
```

**Location:**

- Fixture files: `apps/api/tests/fixtures/` — raw .ics strings for iCalendar tests
- Mock payloads: inline in test files (`api/client.test.ts`, etc.)

## Coverage

**Requirements:** None enforced (no coverage thresholds in vitest.config.ts)

**Current State:**

- Backend: Partial coverage — broker modules (expand, sync, write, crypto, vevent) tested; route handlers mostly untested
- Frontend: Good coverage of utility functions (colorUtils, eventDateTime, hydrateEvents, calendarConfig) and API client

**View Coverage:**

```bash
# Generate coverage report (requires @vitest/coverage-v8)
vitest run --coverage
```

## Test Types

**Unit Tests:**

- Scope: Single function or small module in isolation (mocks external dependencies)
- Approach: Test input → output contracts, edge cases, error conditions
- Examples: `lib/colorUtils.test.ts`, `broker/crypto.test.ts`, `api/client.test.ts`

**Integration Tests:**

- Scope: Multi-module behavior (e.g., route handler + DB + auth middleware)
- Approach: Test realistic user flows using `app.request()` for HTTP semantics
- Examples: `health.test.ts` (GET /health with mocked DB)
- No external API calls (Fastmail, Authelia mocked)

**E2E Tests:**

- Not implemented; would require running a real server + browser
- Currently using `playwright-cli` skill for browser-based smoke tests of UI (per project CLAUDE.md)

## Common Patterns

**Async Testing:**

```typescript
it('returns { uid } on success', async () => {
  vi.mocked(fetch).mockResolvedValueOnce({
    ok: true,
    json: async () => ({ uid: 'returned-uid' }),
  } as Response);

  const { createEvent } = await import('./client.js');
  const result = await createEvent(payload);

  expect(result).toEqual({ uid: 'returned-uid' });
});
```

**Error Testing:**

```typescript
it('throws on non-ok response', async () => {
  vi.mocked(fetch).mockResolvedValueOnce({
    ok: false,
    status: 400,
    json: async () => ({ error: 'Bad Request' }),
  } as Response)

  const { createEvent } = await import('./client.js')

  await expect(
    createEvent({ title: '', ... })
  ).rejects.toThrow()
})
```

**Status Code Testing:**

```typescript
it('returns 503 when DB round-trip throws', async () => {
  const { db } = await import('../src/db/client.js');
  vi.mocked(db.execute).mockRejectedValueOnce(new Error('DB connection failed'));

  const { app } = await import('../src/index.js');
  const res = await app.request('/health');

  expect(res.status).toBe(503);
});
```

**Fixture-Based Testing:**

```typescript
describe('expandOccurrences — DST correctness', () => {
  it('returns 10:00 America/New_York wall-clock time on BOTH sides of March 2026 DST boundary', () => {
    const rawVevent = loadFixture('weekly-dst.ics');
    const windowStart = new Date('2026-03-01T00:00:00Z');
    const windowEnd = new Date('2026-04-01T00:00:00Z');

    const occurrences = expandOccurrences(
      rawVevent,
      windowStart,
      windowEnd,
      1,
      'My Calendar',
      1,
      'Alice',
      '#4A90D9',
      false,
    );

    // Check DST correctness: all occurrences must show hour === 10 local time
    for (const occ of occurrences) {
      expect(occ.start).toMatch(/T10:00:00/);
      expect(occ.start).toContain('[America/New_York]');
    }

    // Explicitly check pre- and post-transition occurrences
    const preTransition = occurrences.find((o) => o.start.includes('2026-03-01'));
    const postTransition = occurrences.find((o) => o.start.includes('2026-03-15'));

    expect(preTransition!.start).toContain('-05:00[America/New_York]'); // EST
    expect(postTransition!.start).toContain('-04:00[America/New_York]'); // EDT
  });
});
```

**Zustand Store Testing:**

```typescript
describe('calendarStore', () => {
  it('setEventForm(true, edit, some-uid) updates all three keys', async () => {
    const { useCalendarStore } = await import('../store/calendarStore.js');
    useCalendarStore.getState().setEventForm(true, 'edit', 'some-uid');
    const state = useCalendarStore.getState();

    expect(state.eventFormOpen).toBe(true);
    expect(state.eventFormMode).toBe('edit');
    expect(state.eventFormUid).toBe('some-uid');
  });
});
```

## Test Setup

**Backend (Node environment):**

- `vitest.config.ts` specifies `environment: 'node'` with `globals: true`
- No test-setup file needed (Node has built-in globals)
- Modules imported via `await import(...)` to enable per-test mocking

**Frontend (jsdom environment):**

- `vitest.config.ts` specifies `environment: 'jsdom'` with `globals: true` and `setupFiles: ['./src/test-setup.ts']`
- `test-setup.ts` polyfills `window.matchMedia` (jsdom doesn't implement CSSOM MediaQueryList)
- `test-setup.ts` extends `expect` with `jest-dom` matchers
- Timezone pinned to UTC via `env: { TZ: 'UTC' }` for deterministic date tests (WR-05)

**Example (from `apps/pwa/vitest.config.ts`):**

```typescript
export default defineConfig({
  test: {
    environment: 'jsdom',
    globals: true,
    setupFiles: ['./src/test-setup.ts'],
    env: { TZ: 'UTC' },
  },
});
```

**Example (from `apps/pwa/src/test-setup.ts`):**

```typescript
import '@testing-library/jest-dom';

Object.defineProperty(window, 'matchMedia', {
  writable: true,
  value: (query: string) => ({
    matches: false,
    media: query,
    // ... other MediaQueryList methods
  }),
});
```

## Known Testing Gaps

**Backend Route Handlers:**

- GET /api/events, POST /api/events/create, PATCH /api/events/:uid/edit, DELETE /api/events/:uid — no route tests yet (in scope for Phase 5 / Plan 05)
- GET /api/events/writable-calendars, GET /api/events/sync-status — no route tests
- SSE route (`/api/sse`) — not tested
- Auth flow tests (dev-bypass, OIDC session) partially covered; integration tests with Authelia not applicable

**Frontend Components:**

- EventForm, DeleteConfirmationDialog, CalendarShell — no component tests yet
- SSE event listener integration (real-time list updates) — not tested

**Integration:**

- Full end-to-end flow (login → fetch events → create event → poll sync-status) — not covered
- Database transaction rollback on error — not explicitly tested

---

_Testing analysis: 2026-06-09_
