Claude Code: Claude Code Basic Usage

> Create src/services/email.ts with email sending service:
> - Support HTML and plain text formats
> - Use template engine for rendering
> - Add retry mechanism (max 3 attempts)
> - Write unit tests (mock SMTP)

Claude Code:
  → Creating src/services/email.ts
  → Creating src/services/__tests__/email.test.ts
  → Installing dependencies: nodemailer, handlebars
  → Running: npm test -- email.test.ts
  ✅ 5 tests passed

> Add password reset functionality to UserService

Claude Code:
  → Reading src/services/user.ts
  → Reading src/models/user.ts
  → Reading src/services/email.ts (existing email service)
  → Modifying src/services/user.ts (adding resetPassword)
  → Modifying src/routes/user.ts (adding POST /reset-password)
  → Creating tests for password reset
  ✅ All tests passed

> Create complete Product CRUD module:
> 1. Prisma model definition
> 2. Repository layer
> 3. Service layer
> 4. Controller layer
> 5. Route definitions
> 6. Complete tests

Claude Code: Created 6 files, 12 tests all passing ✅

> Fix the relativeTime calculation error in src/utils/date.ts when crossing years

Claude Code:
  → Reading src/utils/date.ts
  → Found bug: relativeTime uses daysOnly comparison
  → Fixing: adding year boundary check
  → Running: npm test -- date.test.ts
  ✅ All tests passed (including new edge case)

> Run tests and fix all failing cases

Claude Code:
  → Running: npm test
  ❌ 3 tests failed
  → Reading failed test files...
  → Fixing each failing test
  → Running: npm test
  ✅ All 47 tests passed

> App startup error: TypeError: Cannot read property 'id' of undefined at UserController.getProfile

Claude Code:
  → Found: getProfile doesn't check if req.user exists
  → Adding null check with proper error response
  → Running: npm test -- user.controller.test.ts
  ✅ All tests passed

> Refactor formatCurrency in src/utils/format.ts to use Intl.NumberFormat

Claude Code:
  → Replacing manual formatting with Intl.NumberFormat
  → Adding locale support (default: en-US)
  → Running: npm test -- format.test.ts
  ✅ All tests passed

> Reorganize all utility functions under src/helpers/ into src/utils/ by function:
> - Date related → utils/date.ts
> - String related → utils/string.ts
> - Number related → utils/number.ts
> Update all import paths

Claude Code:
  → Moving functions with proper exports
  → Updating 32 import statements
  → Deleting src/helpers/
  → Running: npm test
  ✅ All 89 tests passed

> Write tests for all services under src/services/ without tests, coverage target 80%

Claude Code:
  → Scanning 8 service files
  → Missing tests found in 3 services
  → Writing tests for each
  → Running: npm test
  ✅ All new tests passed
  Coverage average: 85% ✓

> Review src/auth/jwt.ts for security issues

Claude Code:
  ⚠️ Found 3 issues:
  1. Hardcoded secret key (line 12) → Use env variable
  2. No token expiry validation (line 34) → Add expiry check
  3. Algorithm not specified (line 8) → Force RS256

> Generate API documentation for all routes under src/api/

Claude Code:
  → Reading all route files (12 files)
  → Generating docs/api.md with endpoint listing, examples, and error codes

> Implement user permission system:
> 1. Define Role and Permission models
> 2. Implement RBAC middleware
> 3. Add permission check decorators
> 4. Write complete integration tests
> 5. Generate API documentation

Claude Code: 8 files created, 4 modified, 15 tests passing ✅