---
id: wiki-2026-0508-test-automation
title: Test Automation
category: 10_Wiki/Topics
status: verified
canonical_id: self
aliases: [automated testing, test automation pyramid, CI testing]
duplicate_of: none
source_trust_level: A
confidence_score: 0.95
verification_status: applied
tags: [testing, automation, ci-cd, qa, devops]
raw_sources: []
last_reinforced: 2026-05-10
github_commit: pending
tech_stack:
  language: typescript
  framework: vitest-playwright-msw-pact
---

# Test Automation

## 매 한 줄
> **"매 confidence 의 deploy 의 — 매 tests 의 paying 의"**. Test automation 의 unit / integration / e2e / contract / performance 의 의 CI 의 의 mechanically running 의 의 — 매 regression 의 catch, 매 deploy velocity 의 unlock. 2026 의 stack: Vitest (unit), Playwright (e2e), MSW (API mock), Pact (contract), k6 (load).

## 매 핵심

### 매 testing pyramid (modern)
- **Unit** (60-70%): 매 fast (<100ms each), 매 isolated, 매 logic 의.
- **Integration** (20-30%): 매 real DB / Redis 의 (testcontainers), 매 module boundaries.
- **Component** (10%): 매 React/Vue 의 isolated rendering.
- **E2E** (5-10%): 매 Playwright, 매 critical user journeys 의 only.
- **Contract**: producer/consumer 의 — 매 microservices.

### 매 매 modern paradigms
- **TDD** still relevant for libraries / domain logic.
- **Snapshot testing** judiciously — 매 churn explosion 위험.
- **Property-based** (fast-check, hypothesis) — 매 invariants.
- **Visual regression** (Chromatic, Percy, Playwright trace).

### 매 응용
1. PR-blocking unit + critical e2e.
2. Pre-merge contract tests (Pact broker).
3. Nightly load test + regression budget.

## 💻 패턴

### Vitest unit test
```typescript
import { describe, it, expect, vi } from 'vitest';
import { calcTax } from './tax';

describe('calcTax', () => {
  it.each([
    [100, 'CA', 8.25],
    [100, 'OR', 0],
  ])('%i in %s = %f', (amt, state, expected) => {
    expect(calcTax(amt, state)).toBe(expected);
  });
  it('rejects negative', () => {
    expect(() => calcTax(-1, 'CA')).toThrow(/non-negative/);
  });
});
```

### MSW — API mocking
```typescript
import { http, HttpResponse } from 'msw';
import { setupServer } from 'msw/node';

export const server = setupServer(
  http.get('/api/users/:id', ({ params }) =>
    HttpResponse.json({ id: params.id, name: 'Alice' })),
);
beforeAll(() => server.listen({ onUnhandledRequest: 'error' }));
afterEach(() => server.resetHandlers());
afterAll(() => server.close());
```

### Playwright e2e (critical path)
```typescript
import { test, expect } from '@playwright/test';

test('checkout flow', async ({ page }) => {
  await page.goto('/');
  await page.getByRole('button', { name: /add to cart/i }).first().click();
  await page.getByRole('link', { name: /cart/i }).click();
  await page.getByRole('button', { name: /checkout/i }).click();
  await page.getByLabel(/email/i).fill('test@example.com');
  await page.getByLabel(/card number/i).fill('4242424242424242');
  await page.getByRole('button', { name: /pay/i }).click();
  await expect(page.getByRole('heading', { name: /thank you/i })).toBeVisible();
});
```

### Testcontainers (real Postgres in CI)
```typescript
import { PostgreSqlContainer } from '@testcontainers/postgresql';
let container: any, db: any;
beforeAll(async () => {
  container = await new PostgreSqlContainer('postgres:16').start();
  db = drizzle(postgres(container.getConnectionUri()));
  await migrate(db, { migrationsFolder: './drizzle' });
}, 60_000);
afterAll(async () => container.stop());
```

### Pact contract test (consumer)
```typescript
import { PactV3, MatchersV3 } from '@pact-foundation/pact';
const provider = new PactV3({ consumer: 'web', provider: 'api' });
provider.given('user 1 exists').uponReceiving('a request for user 1')
  .withRequest({ method: 'GET', path: '/users/1' })
  .willRespondWith({ status: 200, body: MatchersV3.like({ id: 1, name: 'Alice' }) });
await provider.executeTest(async (mock) => {
  const r = await fetch(`${mock.url}/users/1`);
  expect((await r.json()).name).toBe('Alice');
});
```

### Property-based (fast-check)
```typescript
import fc from 'fast-check';
test('reverse twice = identity', () => {
  fc.assert(fc.property(fc.array(fc.integer()), (arr) => {
    expect([...arr].reverse().reverse()).toEqual(arr);
  }));
});
```

### Flaky-test quarantine (Playwright)
```typescript
test.describe.configure({ retries: 2 });
test('flaky-known @quarantine', async ({ page }) => { /* ... */ });
// CI: skip @quarantine on PR, run nightly only
```

### k6 load test
```javascript
import http from 'k6/http';
import { check } from 'k6';
export const options = {
  stages: [{ duration: '2m', target: 100 }, { duration: '5m', target: 100 }],
  thresholds: { http_req_duration: ['p(99)<500'] },
};
export default () => {
  const r = http.get('https://staging.app/api/items');
  check(r, { '200': (x) => x.status === 200 });
};
```

## 매 결정 기준
| 상황 | Layer |
|---|---|
| pure function / domain logic | unit (Vitest) |
| DB query / SQL correctness | integration (testcontainers) |
| critical revenue path | e2e (Playwright) |
| microservice API stability | contract (Pact) |
| invariant property | property-based (fast-check) |

**기본값**: 60/30/10 unit/integration/e2e split, MSW for external APIs, testcontainers for DB, Pact for service boundaries.

## 🔗 Graph
- 부모: [[Software Quality]]
- 변형: [[TDD]] · [[BDD]] · [[Property-based Testing]]
- 응용: [[Continuous Integration]] · [[Visual Regression]]
- Adjacent: [[Playwright]] · [[Pact]]

## 🤖 LLM 활용
**언제**: test scaffolding from impl, edge-case enumeration, flaky root-cause analysis from trace.zip, snapshot diff explanation.
**언제 X**: auto-generated tests 의 review 없이 의 merge — 매 tautological tests (mock returns x → assert x).

## ❌ 안티패턴
- **Ice-cream cone** (e2e-heavy, unit-light): 매 slow CI, 매 flaky.
- **Mocking what you don't own** (deep mocks of fetch): 매 mock drift.
- **Snapshot of everything**: 매 PR diff 의 noise.
- **Shared mutable state in tests**: 매 order-dependent flaky.
- **No quarantine**: 매 1 flaky 의 CI 의 distrust.

## 🧪 검증 / 중복
- Verified (Vitest docs, Playwright docs, MSW v2, Pact docs, k6 docs, Kent Beck TDD).
- 신뢰도 A.

## 🕓 Changelog
| 날짜 | 변경 |
|---|---|
| 2026-05-08 | Phase 1 |
| 2026-05-10 | Manual cleanup — pyramid + Vitest/Playwright/MSW/Pact patterns |
