2nd/10_Wiki/Topics/AI_and_ML/Extreme-Programming-XP.md

id, title, category, status, canonical_id, aliases, duplicate_of, source_trust_level, confidence_score, verification_status, tags, raw_sources, last_reinforced, github_commit, tech_stack

id	title	category	status	canonical_id	aliases	duplicate_of	source_trust_level	confidence_score	verification_status	tags	raw_sources	last_reinforced	github_commit	tech_stack
wiki-2026-0508-extreme-programming-xp	Extreme Programming (XP)	10_Wiki/Topics	verified	self	XP Beck XP pair programming TDD continuous integration refactoring	none	A	0.96	applied	agile xp tdd pair-programming ci software-engineering beck		2026-05-10	pending	language applicable_to Universal Agile Software Process

Extreme Programming (XP)

매 한 줄

"매 best practice 의 의 의 의 extreme 의 turn". Kent Beck 1999. 매 TDD, 매 pair, 매 CI, 매 refactoring, 매 simple design. 매 modern: 매 XP 의 practices 의 mainstream — 매 XP 의 brand 의 fade, 매 spirit 의 retain (DevOps, trunk-based, AI-paired).

매 핵심

매 12 practices

1. Planning game (story points).
2. Small releases.
3. Metaphor.
4. Simple design (YAGNI).
5. Testing (TDD).
6. Refactoring.
7. Pair programming.
8. Collective ownership.
9. Continuous integration.
10. 40-hour week.
11. On-site customer.
12. Coding standards.

매 5 values

• Communication, Simplicity, Feedback, Courage, Respect.

매 modern legacy

• Trunk-based development.
• CI/CD.
• TDD (still controversial).
• AI-paired (Copilot, Cursor) = modern pair.
• Mob programming.

💻 패턴

TDD cycle (Red-Green-Refactor)

# 매 1. Red — failing test
def test_email_validate():
    assert validate_email('a@b.com') is True
    assert validate_email('invalid') is False

# 매 2. Green — minimum
def validate_email(email):
    return '@' in email

# 매 3. Refactor — pattern
import re
def validate_email(email):
    return bool(re.match(r'^[^\s@]+@[^\s@]+\.[^\s@]+$', email))

Pair programming roles

driver:
  - types code
  - tactical focus
  - explains as goes
navigator:
  - reviews + thinks ahead
  - strategic
  - catches bugs / typos
rotation: every 25 minutes

Mob programming

mob:
  size: 3-5 people
  driver_rotation: 5-10 min
  laptop: single
  goal: continuous learning + team alignment

CI pipeline

on: { push: { branches: [main] } }
jobs:
  test:
    steps:
      - uses: actions/checkout@v4
      - run: npm ci
      - run: npm test
      - run: npm run lint

Story (planning game)

## Story: User can reset password

### As a user
I want to reset my password
So that I can regain access

### Acceptance criteria
- [ ] Email field validates format
- [ ] Confirmation email sent
- [ ] Token expires after 1 hour
- [ ] Old password invalidated

### Estimate: 3 points

Refactor — Extract Method

// 매 before
function processOrder(order) {
  // 매 20 lines mixing validation + calculation + persist
}

// 매 after
function processOrder(order) {
  validate(order);
  const total = calculateTotal(order);
  persist({ ...order, total });
}

Simple design (YAGNI)

// 매 ❌ premature abstraction
class GenericRepository<T, K, ...> { ... }

// 매 ✅ simple
class UserRepository {
  async find(id: string): Promise<User | null> { ... }
  async save(u: User): Promise<void> { ... }
}
// 매 abstract 매 매 3rd similar repo

Continuous integration (trunk-based)

# 매 short-lived branch (< 1 day)
git checkout -b feat/quick-fix
# 매 work
npm test
git add -p; git commit
git push
# 매 PR → review → merge → CI deploy

TDD with AI pair

# 매 modern XP: AI as pair
# 매 driver: human writes test
def test_calculate_discount():
    assert discount(100, 'STUDENT') == 10
    assert discount(100, 'NONE') == 0

# 매 navigator (AI): suggests implementation
def discount(amount, code):
    rules = {'STUDENT': 0.1, 'SENIOR': 0.15}
    return amount * rules.get(code, 0)

On-site customer (modern proxy)

modern_equivalent:
  - product_owner: dedicated PM
  - user_research_loop: weekly
  - support_rotation: engineers in support 1d/sprint
  - real_user_feedback: in-app survey + hotjar

Test coverage gate

# 매 fail PR if coverage drops
- run: npm run coverage
- run: |
    pct=$(jq '.total.lines.pct' coverage/coverage-summary.json)
    if (( $(echo "$pct < 80" | bc -l) )); then exit 1; fi

Refactoring catalog (Fowler)

// 매 Inline Variable
// before
const result = calculate(); return result;
// after
return calculate();

// 매 Replace Magic Number
const TAX_RATE = 0.08;
return total * (1 + TAX_RATE);

매 결정 기준

상황	Practice
Greenfield	All-in XP
Legacy + tests	TDD selectively
Solo dev	TDD + CI
Distributed team	CI + async pair
Scale-up	Trunk + feature flags
AI-augmented	Copilot + TDD

기본값: 매 modern XP = TDD + CI/CD + trunk-based + pair (or AI-pair) + simple design + small release.

🔗 Graph

• 부모: Agile
• 변형: Scrum · Kanban · Mob-Programming
• 응용: TDD · CI-CD · Pair-Programming · Refactoring_Best_Practices
• Adjacent: Trunk-Based-Development · Development Communication Standards · Enterprise-Software-Engineering

🤖 LLM 활용

언제: 매 small team. 매 high-quality requirement. 매 evolving requirement. 언제 X: 매 strict regulatory waterfall.

❌ 안티패턴

• Cherry-pick practices: 매 synergy lose.
• TDD without refactor: 매 cruft.
• Pair as overhead: 매 communication 의 ignore.
• No on-site customer: 매 wrong product.
• CI without tests: 매 false safety.

🧪 검증 / 중복

• Verified (Beck XP Explained 1999/2004).
• 신뢰도 A.

🕓 Changelog

날짜	변경
2026-04-26	XP auto
2026-05-08	Phase 1
2026-05-10	Manual cleanup — 12 practices + 매 TDD / pair / mob / CI / refactor code