# Code Review Process SOP

## Document Information
- **Document ID**: SOP-DEV-001
- **Version**: 1.0
- **Date**: 2025-09-09
- **Author**: Development Team
- **Status**: Active

## 1. Purpose and Scope

### 1.1 Purpose
This SOP defines the standardized process for conducting code reviews to ensure code quality, security, maintainability, and knowledge sharing across the development team.

### 1.2 Scope
This procedure applies to:
- All code changes to production systems
- All pull requests to main/master branch
- Critical bug fixes and hotfixes
- Third-party library integrations

### 1.3 Exclusions
The following are excluded from this process:
- Documentation-only changes
- Configuration file updates (unless security-related)
- Experimental branch development

## 2. Roles and Responsibilities

### 2.1 Code Author
**Responsibilities:**
- Submit code for review in reviewable state
- Provide clear description of changes
- Respond to reviewer feedback promptly
- Make necessary revisions based on feedback
- Ensure all automated checks pass

**Required Actions:**
- Create descriptive pull request
- Self-review code before submission
- Add appropriate labels and assignees
- Link related issues or tickets

### 2.2 Code Reviewer
**Responsibilities:**
- Review code within 24 hours of assignment
- Provide constructive, specific feedback
- Verify code meets quality standards
- Check for security vulnerabilities
- Approve or request changes

**Required Actions:**
- Perform thorough technical review
- Test code changes if necessary
- Document review decisions
- Mentor junior developers

### 2.3 Technical Lead
**Responsibilities:**
- Assign reviewers for complex changes
- Resolve review conflicts
- Ensure process compliance
- Monitor review metrics

## 3. Pre-Review Requirements

### 3.1 Author Checklist
Before submitting code for review, the author must verify:

**Code Quality:**
- [ ] Code follows project coding standards
- [ ] All functions have appropriate documentation
- [ ] Variable and function names are descriptive
- [ ] Code is properly formatted
- [ ] No debugging code or TODO comments left in

**Testing:**
- [ ] All new code has unit tests
- [ ] All tests pass locally
- [ ] Integration tests updated if needed
- [ ] Manual testing completed for UI changes

**Security:**
- [ ] No hardcoded credentials or secrets
- [ ] Input validation implemented
- [ ] Proper error handling in place
- [ ] Security best practices followed

**Performance:**
- [ ] No obvious performance issues
- [ ] Database queries optimized
- [ ] Memory usage considered
- [ ] Caching implemented where appropriate

### 3.2 Automated Checks
All pull requests must pass automated checks:
- [ ] Build succeeds
- [ ] All tests pass
- [ ] Code coverage meets minimum threshold
- [ ] Static analysis tools pass
- [ ] Security scans complete without critical issues

## 4. Review Process

### 4.1 Review Assignment
1. **Automatic Assignment**: System automatically assigns reviewers based on:
   - Code area expertise
   - Current workload
   - Team rotation schedule

2. **Manual Assignment**: Technical lead may manually assign for:
   - Critical security changes
   - Architecture modifications
   - Performance-sensitive code

### 4.2 Review Timeline
| Priority | Response Time | Review Completion |
|----------|---------------|-------------------|
| Critical/Hotfix | 2 hours | 4 hours |
| High | 4 hours | 24 hours |
| Medium | 24 hours | 48 hours |
| Low | 48 hours | 1 week |

### 4.3 Review Categories

#### 4.3.1 Technical Review
**Focus Areas:**
- Code correctness and logic
- Algorithm efficiency
- Data structure usage
- Error handling
- Resource management

**Review Questions:**
- Does the code do what it's supposed to do?
- Are there any logical errors?
- Is the algorithm efficient?
- Are edge cases handled?
- Is error handling comprehensive?

#### 4.3.2 Design Review
**Focus Areas:**
- Architecture consistency
- Design patterns usage
- SOLID principles adherence
- Separation of concerns
- Code reusability

**Review Questions:**
- Does the design fit the overall architecture?
- Are appropriate design patterns used?
- Is the code modular and reusable?
- Are dependencies properly managed?
- Is the interface design clean?

#### 4.3.3 Security Review
**Focus Areas:**
- Input validation
- Authentication/authorization
- Data encryption
- Injection vulnerabilities
- Information disclosure

**Review Questions:**
- Is user input properly validated?
- Are authentication mechanisms secure?
- Is sensitive data protected?
- Are there any injection vulnerabilities?
- Could this expose sensitive information?

#### 4.3.4 Performance Review
**Focus Areas:**
- Algorithm complexity
- Database query efficiency
- Memory usage
- Network calls
- Caching strategy

**Review Questions:**
- Are algorithms optimally efficient?
- Are database queries optimized?
- Is memory usage reasonable?
- Are network calls minimized?
- Is caching used appropriately?

## 5. Review Guidelines

### 5.1 Providing Feedback

#### 5.1.1 Feedback Categories
Use these prefixes to categorize feedback:

**MUST FIX:** Critical issues that must be resolved
```
MUST FIX: This function has a SQL injection vulnerability
```

**SHOULD FIX:** Important issues that should be addressed
```
SHOULD FIX: Consider using a more descriptive variable name
```

**CONSIDER:** Suggestions for improvement
```
CONSIDER: Could this be refactored to reduce complexity?
```

**NITPICK:** Minor style or preference issues
```
NITPICK: Extra whitespace on line 42
```

**PRAISE:** Positive feedback for good practices
```
PRAISE: Excellent error handling implementation
```

#### 5.1.2 Effective Feedback Principles
- **Be Specific**: Point to exact lines and explain the issue
- **Be Constructive**: Suggest improvements, don't just criticize
- **Be Respectful**: Focus on code, not the person
- **Be Educational**: Explain why changes are needed
- **Be Timely**: Provide feedback promptly

### 5.2 Common Review Points

#### 5.2.1 Code Structure
```python
# GOOD: Clear, single responsibility
def calculate_user_discount(user: User, order: Order) -> float:
    """Calculate discount percentage for user's order."""
    if user.is_premium and order.total > 100:
        return 0.15
    elif user.is_member:
        return 0.10
    return 0.0

# BAD: Multiple responsibilities, unclear logic
def process_order(user, order, payment):
    # Calculate discount
    discount = 0
    if user.type == "premium" and order.total > 100:
        discount = 0.15
    # Process payment
    payment.charge(order.total - discount)
    # Send email
    send_email(user.email, "Order processed")
    # Update inventory
    update_inventory(order.items)
```

#### 5.2.2 Error Handling
```python
# GOOD: Specific error handling
try:
    user = get_user_by_id(user_id)
    if not user:
        raise UserNotFoundError(f"User {user_id} not found")
    return user
except DatabaseError as e:
    logger.error(f"Database error retrieving user {user_id}: {e}")
    raise ServiceUnavailableError("User service temporarily unavailable")

# BAD: Generic exception handling
try:
    user = get_user_by_id(user_id)
    return user
except Exception:
    return None
```

## 6. Review Outcomes

### 6.1 Approval Types

#### 6.1.1 Approve
- Code meets all quality standards
- No blocking issues identified
- Ready for merge

#### 6.1.2 Approve with Comments
- Minor issues that don't block merge
- Suggestions for future improvements
- Non-critical feedback

#### 6.1.3 Request Changes
- Issues that must be fixed before merge
- Security vulnerabilities found
- Significant design problems

### 6.2 Conflict Resolution
When reviewers disagree:

1. **Discussion**: Reviewers discuss the issue in comments
2. **Technical Lead**: Technical lead makes final decision
3. **Architecture Review**: For architectural disputes, escalate to architecture team
4. **Documentation**: Document decision rationale

## 7. Special Review Types

### 7.1 Hotfix Review
**Expedited Process:**
- Single reviewer required (instead of two)
- 2-hour response time
- Focus on fix correctness and minimal impact
- Post-deployment review within 24 hours

### 7.2 Security-Critical Review
**Enhanced Process:**
- Security team member must review
- Threat modeling verification
- Security testing required
- Documentation of security considerations

### 7.3 Performance-Critical Review
**Enhanced Process:**
- Performance testing required
- Benchmark comparisons
- Resource usage analysis
- Load testing verification

## 8. Metrics and Monitoring

### 8.1 Review Metrics
Track the following metrics monthly:

**Efficiency Metrics:**
- Average review time
- Time to first review
- Number of review iterations
- Review queue length

**Quality Metrics:**
- Defects found in review vs. production
- Review coverage percentage
- Code quality scores
- Security issues caught

**Participation Metrics:**
- Reviews per developer
- Review response time
- Feedback quality scores

### 8.2 Continuous Improvement
- Monthly review process retrospectives
- Quarterly metrics analysis
- Annual process updates
- Tool evaluation and updates

## 9. Tools and Integration

### 9.1 Required Tools
- **Git**: Version control system
- **GitHub/GitLab**: Code review platform
- **IDE Integration**: Review plugins
- **Static Analysis**: Automated code analysis
- **Security Scanning**: Vulnerability detection

### 9.2 Review Automation
Automate routine checks:
- Code formatting verification
- Test coverage calculation
- Security vulnerability scanning
- Documentation completeness
- License compliance checking

## 10. Training and Onboarding

### 10.1 New Developer Training
All new developers must complete:
- Code review process training
- Tool usage training
- Security awareness training
- Project-specific guidelines review

### 10.2 Ongoing Training
- Monthly code review best practices sessions
- Quarterly security update training
- Annual process improvement workshops

## 11. Process Compliance

### 11.1 Enforcement
- All production code must be reviewed
- No direct commits to main branch
- Bypass only for emergency hotfixes (with post-review)
- Regular audit of review compliance

### 11.2 Exceptions
Document any exceptions with:
- Justification for exception
- Risk assessment
- Mitigation measures
- Approval authority

## 12. Revision History

| Version | Date | Author | Changes |
|---------|------|--------|---------|
| 1.0 | 2025-09-09 | Development Team | Initial version |

## Appendix A: Review Checklist

### Technical Review Checklist
- [ ] Code compiles and runs without errors
- [ ] All tests pass
- [ ] Code follows project standards
- [ ] Error handling is appropriate
- [ ] Performance considerations addressed
- [ ] Security best practices followed
- [ ] Documentation is complete
- [ ] No hardcoded values or credentials
- [ ] Resource cleanup is proper
- [ ] Edge cases are handled

### Security Review Checklist
- [ ] Input validation implemented
- [ ] Output encoding applied
- [ ] Authentication verified
- [ ] Authorization checked
- [ ] Sensitive data protected
- [ ] Injection attacks prevented
- [ ] Error messages don't leak information
- [ ] Logging doesn't expose secrets
- [ ] Third-party dependencies are secure