2nd/10_Wiki/Topics/Architecture/Test Automation Pyramid.md

---
id: wiki-2026-0508-test-automation-pyramid
title: Test Automation Pyramid
category: 10_Wiki/Topics
status: verified
canonical_id: self
aliases: [Test Pyramid, 테스트 피라미드, Cohn Pyramid]
duplicate_of: none
source_trust_level: A
confidence_score: 0.92
verification_status: applied
tags: [testing, architecture, pyramid, automation]
raw_sources: []
last_reinforced: 2026-05-10
github_commit: pending
tech_stack:
  language: TypeScript
  framework: Vitest/Playwright
---

# Test Automation Pyramid

## 매 한 줄
> **"매 unit test 가 base, e2e 가 tip"**. Mike Cohn 의 2009 Succeeding with Agile 에서 origin — slow/expensive UI test 의 over-reliance 의 anti-pattern. 매 2026 modern stack 은 unit + integration + contract + e2e 의 4-layer 의 evolution.

## 매 핵심

### 매 layers (bottom-up)
- **Unit (70%)**: pure function, 단일 class, <10ms, in-memory.
- **Integration (20%)**: DB, HTTP client, 매 real adapter, 100ms-1s.
- **Contract (5-10%)**: provider/consumer 매 Pact / OpenAPI schema.
- **E2E (5%)**: 매 full user journey, Playwright/Cypress, 10s+.

### 매 anti-shapes
- **Ice cream cone**: 매 e2e heavy, unit 부족 — slow CI, flaky.
- **Hourglass**: 매 unit + e2e 만, integration 의 gap — production bug 의 source.
- **Cupcake**: manual test layer 의 추가 — automation 의 의미 상실.

### 매 응용
1. CI pipeline tier — unit on every commit, e2e on merge to main.
2. Bug 발견 시 lowest-level test 의 추가 (root cause level).
3. Test budget 분배 결정 (시간 / 신뢰도 trade-off).

## 💻 패턴

### Vitest unit test
```typescript
import { describe, it, expect } from 'vitest';
import { calculateDiscount } from './pricing';

describe('calculateDiscount', () => {
  it('applies 10% for VIP customer', () => {
    expect(calculateDiscount(100, 'VIP')).toBe(90);
  });

  it('returns full price for standard customer', () => {
    expect(calculateDiscount(100, 'STANDARD')).toBe(100);
  });
});
```

### Integration test (real Postgres via testcontainers)
```typescript
import { PostgreSqlContainer } from '@testcontainers/postgresql';

let container: StartedTestContainer;
beforeAll(async () => {
  container = await new PostgreSqlContainer('postgres:16').start();
  process.env.DATABASE_URL = container.getConnectionUri();
});

it('persists user', async () => {
  const repo = new UserRepository();
  await repo.save({ id: '1', name: 'Alice' });
  const found = await repo.findById('1');
  expect(found?.name).toBe('Alice');
});
```

### Contract test (Pact consumer)
```typescript
import { PactV3, MatchersV3 } from '@pact-foundation/pact';

const provider = new PactV3({ consumer: 'web', provider: 'api' });

provider
  .uponReceiving('a request for user')
  .withRequest({ method: 'GET', path: '/users/1' })
  .willRespondWith({
    status: 200,
    body: { id: MatchersV3.string('1'), name: MatchersV3.string('Alice') }
  });
```

### Playwright E2E
```typescript
import { test, expect } from '@playwright/test';

test('user can checkout', async ({ page }) => {
  await page.goto('/products/42');
  await page.getByRole('button', { name: 'Add to cart' }).click();
  await page.goto('/cart');
  await page.getByRole('button', { name: 'Checkout' }).click();
  await expect(page).toHaveURL(/\/orders\/\w+/);
});
```

### Test pyramid CI distribution (GitHub Actions)
```yaml
jobs:
  unit:
    runs-on: ubuntu-latest
    steps:
      - run: pnpm test:unit  # <30s, every push
  integration:
    needs: unit
    steps:
      - run: pnpm test:integration  # <5min, every PR
  e2e:
    needs: integration
    if: github.ref == 'refs/heads/main'
    steps:
      - run: pnpm test:e2e  # <20min, main only
```

### Coverage budget enforcement
```typescript
// vitest.config.ts
export default {
  test: {
    coverage: {
      thresholds: {
        lines: 80,
        functions: 80,
        branches: 75,
        statements: 80,
      },
    },
  },
};
```

## 매 결정 기준
| 상황 | Approach |
|---|---|
| Pure logic, no I/O | Unit test |
| DB query / external HTTP | Integration with testcontainers |
| Microservice boundary | Contract test (Pact) |
| Critical user journey | E2E (smoke only, 5-10 tests) |
| Visual regression | Playwright trace + screenshot |

**기본값**: 70/20/10 split (unit/integration/e2e), 매 contract test 는 microservice 환경에서만.

## 🔗 Graph
- 부모: [[Test-Driven_Development]] · [[Testability_Architecture]]
- 응용: [[Continuous Integration]] · [[CI_CD_Pipeline]]
- Adjacent: [[Mock Objects (가짜 객체)]] · [[Property-Based Testing]]

## 🤖 LLM 활용
**언제**: test strategy 설계, CI tier 분배 결정, anti-shape 진단.
**언제 X**: 매 specific test framework 의 deep API 질문 — 매 official docs 의 우선.

## ❌ 안티패턴
- **All e2e**: 매 30분 CI, flaky retry hell.
- **No integration**: unit pass + production fail (mock drift).
- **Test pyramid as goal**: 매 ratio 의 obsession — 매 actual confidence 가 metric.
- **100% coverage**: meaningless — 매 critical path coverage 가 진짜.

## 🧪 검증 / 중복
- Verified (Mike Cohn, *Succeeding with Agile* 2009; Martin Fowler 2012 update).
- 신뢰도 A.
- 중복: [[Test Pyramid (테스트 피라미드)]] redirect.

## 🕓 Changelog
| 날짜 | 변경 |
|---|---|
| 2026-05-08 | Phase 1 |
| 2026-05-10 | Manual cleanup — full canonical content with 4-layer modern pyramid |