10 KiB
10 KiB
Refactor
Performs safe, step-by-step code refactoring with quantitative SOLID principles evaluation. Visualizes technical debt and clarifies improvement priorities.
Usage
# Identify complex code and create refactoring plan
find . -name "*.js" -exec wc -l {} + | sort -rn | head -10
"Refactor large files to reduce complexity"
# Detect and consolidate duplicate code
grep -r "function processUser" . --include="*.js"
"Consolidate duplicate functions using Extract Method"
# Evaluate SOLID principles violations
grep -r "class.*Service" . --include="*.js" | head -10
"Assess whether these classes follow Single Responsibility Principle"
Basic Examples
# Find long methods
grep -A 50 "function" src/*.js | grep -B 50 -A 50 "return" | wc -l
"Split methods over 50 lines using Extract Method"
# Find complex conditions
grep -r "if.*if.*if" . --include="*.js"
"Improve nested conditions using Strategy pattern"
# Find code smells
grep -r "TODO\|FIXME\|HACK" . --exclude-dir=node_modules
"Resolve technical debt in comments"
Refactoring Techniques
Extract Method (Split Big Functions)
// Before: Long method
function processOrder(order) {
// 50 lines of complex processing
}
// After: Separation of responsibilities
function processOrder(order) {
validateOrder(order);
calculateTotal(order);
saveOrder(order);
}
Replace Conditional with Polymorphism (Remove Switch/If Chains)
// Before: switch statement
function getPrice(user) {
switch (user.type) {
case "premium":
return basePrice * 0.8;
case "regular":
return basePrice;
}
}
// After: Strategy pattern
class PremiumPricing {
calculate(basePrice) {
return basePrice * 0.8;
}
}
SOLID Principles Scoring (0-100 points)
Evaluation Criteria and Scoring
S - Single Responsibility (20 points)
├─ Number of responsibilities: 1 (20pts) | 2 (15pts) | 3 (10pts) | 4+ (5pts)
├─ Method count: <7 (+5pts) | 7-15 (+3pts) | >15 (0pts)
├─ Clear reasons for change: Clear (+5pts) | Unclear (0pts)
└─ Example score: UserService (auth + data processing) = 10 points
O - Open/Closed (20 points)
├─ Extension points: Strategy/Template Method (20pts) | Inheritance only (10pts) | None (5pts)
├─ Existing code changes for new features: Not needed (+5pts) | Minimal (+3pts) | Required (0pts)
├─ Interface usage: Appropriate (+5pts) | Partial (+3pts) | None (0pts)
└─ Example score: PaymentProcessor (Strategy) = 20 points
L - Liskov Substitution (20 points)
├─ Derived class contract compliance: Complete (20pts) | Partial (10pts) | Violated (0pts)
├─ Precondition strengthening: None (+5pts) | Present (-5pts)
├─ Postcondition weakening: None (+5pts) | Present (-5pts)
└─ Example score: Square extends Rectangle = 0 points (violated)
I - Interface Segregation (20 points)
├─ Interface size: 1-3 methods (20pts) | 4-7 (15pts) | 8+ (5pts)
├─ Unused method implementations: None (+5pts) | 1-2 (+2pts) | 3+ (0pts)
├─ Role clarity: Single role (+5pts) | Multiple roles (0pts)
└─ Example score: Readable/Writable separation = 20 points
D - Dependency Inversion (20 points)
├─ Dependency direction: Abstractions only (20pts) | Mixed (10pts) | Concretions only (5pts)
├─ DI usage: Constructor Injection (+5pts) | Setter (+3pts) | None (0pts)
├─ Testability: Mockable (+5pts) | Difficult (0pts)
└─ Example score: Repository Pattern = 20 points
Total Score = S + O + L + I + D
├─ 90-100 points: Excellent (SOLID compliant)
├─ 70-89 points: Good (Minor improvements needed)
├─ 50-69 points: Fair (Refactoring recommended)
├─ 30-49 points: Poor (Major improvements required)
└─ 0-29 points: Critical (Design overhaul required)
Technical Debt Quantification
Debt Calculation Formula
Technical Debt (time) = Complexity Score × Impact Range × Fix Difficulty
Complexity Score:
├─ Cyclomatic complexity: 1-5 (low) | 6-10 (med) | 11-20 (high) | 21+ (critical)
├─ Cognitive complexity: Nesting depth × conditional branches
├─ Lines of code: <50 (1pt) | 50-200 (2pts) | 200-500 (3pts) | 500+ (5pts)
└─ Duplication rate: 0-10% (1pt) | 10-30% (2pts) | 30-50% (3pts) | 50%+ (5pts)
Impact Range:
├─ Dependent modules: Direct dependencies + Indirect × 0.5
├─ Usage frequency: API calls/day
├─ Business importance: Critical (×3) | High (×2) | Medium (×1) | Low (×0.5)
└─ Team knowledge: 1 person knows (×3) | 2-3 (×2) | 4+ (×1)
Fix Difficulty:
├─ Test coverage: 0% (×3) | <50% (×2) | 50-80% (×1.5) | >80% (×1)
├─ Documentation: None (×2) | Insufficient (×1.5) | Adequate (×1)
├─ Dependencies: Tightly coupled (×3) | Moderate (×2) | Loosely coupled (×1)
└─ Change risk: Breaking change (×3) | Backward compatibility (×2) | Safe (×1)
Cost Conversion:
├─ Time cost: Debt time × Developer hourly rate
├─ Opportunity cost: New feature delay days × Daily revenue impact
├─ Quality cost: Bug probability × Fix cost × Frequency
└─ Total cost: Time + Opportunity + Quality costs
Priority Matrix
| Priority | Impact | Fix Cost | Time Savings | Investment ROI | Response Deadline |
|---|---|---|---|---|---|
| Critical (Immediate) | High | Low | > 5x | Invest 1h → Save 5h+ | Immediately |
| Important (Planned) | High | High | 2-5x | Invest 1h → Save 2-5h | Within 1 month |
| Watch (Monitor) | Low | High | 1-2x | Invest 1h → Save 1-2h | Within 3 months |
| Acceptable (Tolerable) | Low | Low | < 1x | Investment = Savings | No action needed |
Refactoring Process
-
Current Analysis and Measurement
- Measure complexity (cyclomatic & cognitive)
- Calculate SOLID score (0-100 points)
- Quantify technical debt (time/cost)
- Create priority matrix
-
Step-by-Step Execution
- Small steps (15-30 minute increments)
- Run tests after each change
- Frequent commits
- Continuous SOLID score measurement
-
Quality Verification
- Maintain test coverage
- Measure performance
- Verify technical debt reduction
- Code review
Common Code Smells and Debt Scores
| Code Smell | Detection Criteria | Debt Score | Improvement Method |
|---|---|---|---|
| God Object | Responsibilities >3, Methods >20 | High (15-20h) | Extract Class, Apply SRP |
| Long Method | Lines >50, Complexity >10 | Medium (5-10h) | Extract Method |
| Duplicate Code | Duplication rate >30% | High (10-15h) | Extract Method/Class |
| Large Class | Lines >300, Methods >15 | High (10-20h) | Extract Class |
| Long Parameter List | Parameters >4 | Low (2-5h) | Parameter Object |
| Feature Envy | Other class references >5 | Medium (5-10h) | Move Method |
| Data Clumps | Repeated argument groups | Low (3-5h) | Extract Class |
| Primitive Obsession | Excessive primitive type usage | Medium (5-8h) | Replace with Object |
| Switch Statements | Cases >5 | Medium (5-10h) | Strategy Pattern |
| Shotgun Surgery | Change impact areas >3 | High (10-15h) | Move Method/Field |
Practical Example: SOLID Score Evaluation
// Evaluation target: UserService class
class UserService {
constructor(db, cache, logger, emailService) { // 4 dependencies
this.db = db;
this.cache = cache;
this.logger = logger;
this.emailService = emailService;
}
// Responsibility 1: Authentication
authenticate(username, password) { /* ... */ }
refreshToken(token) { /* ... */ }
// Responsibility 2: User management
createUser(data) { /* ... */ }
updateUser(id, data) { /* ... */ }
deleteUser(id) { /* ... */ }
// Responsibility 3: Notifications
sendWelcomeEmail(user) { /* ... */ }
sendPasswordReset(email) { /* ... */ }
}
// SOLID Score Evaluation Result
S: 10 points (3 responsibilities: auth, CRUD, notifications)
O: 5 points (No extension points, direct implementation)
L: 15 points (No inheritance, not applicable)
I: 10 points (Interfaces not segregated)
D: 10 points (Depends on concrete classes)
Total: 50 points (Fair - Refactoring recommended)
// Technical Debt
Complexity: 15 (7 methods, 3 responsibilities)
Impact Range: 8 (Authentication used across all features)
Fix Difficulty: 2 (Tests exist, documentation lacking)
Debt Time: 15 × 8 × 2 = 240 hours
Priority: Critical (Auth system requires immediate attention)
Improved Implementation Example
// After applying SOLID principles (Score: 90 points)
// S: Single Responsibility (20 points)
class AuthenticationService {
authenticate(credentials) { /* ... */ }
refreshToken(token) { /* ... */ }
}
// O: Open/Closed (20 points)
class UserRepository {
constructor(storage) { // Strategy Pattern
this.storage = storage;
}
save(user) { return this.storage.save(user); }
}
// I: Interface Segregation (20 points)
interface Readable {
find(id);
findAll();
}
interface Writable {
save(entity);
delete(id);
}
// D: Dependency Inversion (20 points)
class UserService {
constructor(
private auth: IAuthService,
private repo: IUserRepository,
private notifier: INotificationService
) {}
}
// Debt reduction: 240 hours → 20 hours (92% reduction)
Automation Support
# SOLID score measurement
npx solid-analyzer src/ --output report.json
# Complexity analysis
npx complexity-report src/ --format json
sonar-scanner -Dsonar.javascript.lcov.reportPaths=coverage/lcov.info
# Technical debt visualization
npx code-debt-analyzer --config .debt.yml
# Code formatting
npm run lint:fix
prettier --write src/
# Test execution and coverage
npm test -- --coverage
npm run test:mutation # Mutation testing
Important Rules
- No functional changes: Don't alter external behavior
- Test first: Add tests before refactoring
- Step-by-step approach: No large changes at once
- Continuous verification: Run tests at each step