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Chapter 18: Practical Examples


Web Application Development

Case: Create Blog System

18.1 Web 应用开发

bash
You: create a complete blog system including:
- RESTful API (Node.js + Express)
- MongoDB database
- JWT authentication
- CRUD operations (posts, comments)
- Unit tests

Claude: I'll create a complete blog system. Let me break this down:

[Step 1: Project Setup]
✓ Created package.json
✓ Installed dependencies

[Step 2: Database Models]
✓ models/User.js
✓ models/Post.js
✓ models/Comment.js

[Step 3: API Routes]
✓ routes/auth.js (login, register)
✓ routes/posts.js (CRUD)
✓ routes/comments.js (CRUD)

[Step 4: Middleware]
✓ middleware/auth.js (JWT verification)
✓ middleware/validation.js

[Step 5: Tests]
✓ 32 tests created and passing

[Step 6: Documentation]
✓ API documentation generated

Blog system complete! 🎉

API Development

Case: E-commerce API

18.2 API 接口开发

bash
You: create e-commerce API including:
- User management
- Product catalog
- Shopping cart
- Order processing
- Payment integration (Stripe)

Claude: Creating e-commerce API...

[Architecture Design]
 API blueprint created
 Database schema designed

[Implementation]
 User service
 Product service
 Cart service
 Order service
 Payment service (Stripe integration)

[API Endpoints]
POST   /api/auth/register
POST   /api/auth/login
GET    /api/products
POST   /api/cart/add
POST   /api/orders
POST   /api/payments/charge

[Tests & Documentation]
 45 integration tests
 OpenAPI documentation

E-commerce API ready! 🛒

Code Review and Refactoring

Case: Legacy Code Refactoring

18.3 代码审查与重构

bash
You: refactor legacy/app.js, a 1500-line file,
needs:
- Split into modules
- Apply design patterns
- Improve testability
- Maintain backward compatibility

Claude: Analyzing legacy code...

[Analysis]
- 1,523 lines of code
- Multiple responsibilities mixed
- No tests
- Tight coupling

[Refactoring Plan]
1. Extract routes routes/
2. Extract services services/
3. Extract utilities utils/
4. Apply dependency injection
5. Create tests

[Execution]
 Refactored into 12 modules
 Applied MVC pattern
 Created 68 unit tests
 All existing functionality preserved
 100% backward compatible

Refactoring complete!
Before: 1,523 lines, 1 file
After: 850 lines, 12 files
Test coverage: 92%

Automation Scripts

Case: CI/CD Pipeline

18.4 自动化脚本

bash
You: create complete CI/CD pipeline:
- GitHub Actions
- Automated tests
- Code quality checks
- Docker builds
- Automated deployment

Claude: Creating CI/CD pipeline...

 .github/workflows/ci.yml
 .github/workflows/deploy.yml
 Dockerfile
 docker-compose.yml
 deployment scripts

Pipeline stages:
1. Lint & Format check
2. Run tests
3. Build Docker image
4. Security scan
5. Deploy to staging
6. Run smoke tests
7. Deploy to production

Pipeline ready! 🚀

Test-Driven Development

Case: TDD Practice

18.5 测试驱动开发

bash
You: develop user registration feature using TDD

Claude: Starting TDD approach...

[Red Phase - Write failing tests]
 test/auth.test.js created
  - should register new user
  - should validate email format
  - should hash password
  - should prevent duplicate email
  - should return JWT token

[Green Phase - Implement minimum code]
 src/auth.js implemented
  All tests passing

[Refactor Phase - Improve code]
 Extracted validation logic
 Improved error handling
 Added JSDoc comments

TDD cycle complete!
Tests: 5/5 passing
Coverage: 100%

Summary

In this chapter, we learned through practical examples:

  • ✅ Web application development (Blog system)
  • ✅ API development (E-commerce API)
  • ✅ Code review and refactoring (Legacy code)
  • ✅ Automation scripts (CI/CD pipeline)
  • ✅ Test-driven development (TDD practice)

Key Takeaways:

  • Claude Code handles complex real-world projects
  • Complete workflow support from planning to implementation
  • Automated testing and documentation generation
  • Best practices application

Next Step: The final chapter is Resources!


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