Code Quality Metrics

Code Quality Metrics

Measuring code quality helps teams identify problems early and track improvement over time. Key metrics provide objective data about the health and maintainability of your codebase.

Code Coverage

  CODE COVERAGE
  =============

  Measures the percentage of code tested by automated tests.

  +----------------------------------------------+
  | Coverage Report                              |
  +----------------------------------------------+
  | File              | Lines | Branches | Funcs |
  |-------------------|-------|----------|-------|
  | auth.js           |  95%  |   90%    | 100%  |
  | database.js       |  82%  |   75%    |  90%  |
  | utils.js          |  45%  |   30%    |  60%  |
  |-------------------|-------|----------|-------|
  | Overall           |  74%  |   65%    |  83%  |
  +----------------------------------------------+

  Coverage Types:
  - Line Coverage:    % of lines executed
  - Branch Coverage:  % of if/else paths taken
  - Function Coverage: % of functions called

  Target: 70-80% is reasonable for most projects

Technical Debt

  TECHNICAL DEBT QUADRANT
  ========================

                    Deliberate
                        |
          +-------------+-------------+
          |                           |
   Reckless|   "We don't have time    | Prudent
          |    for design"           |
          |                           |
          +-------------+-------------+
                        |
                   Inadvertent

  Debt Types:
  - Code Debt:    Messy, duplicated code
  - Design Debt:  Poor architecture decisions
  - Testing Debt:  Insufficient test coverage
  - Documentation Debt: Missing or outdated docs

  Debt is not always bad — just track and manage it.

Other Quality Metrics

  KEY QUALITY METRICS
  ===================

  Cyclomatic Complexity
  - Measures code complexity based on decision points
  - Target: < 10 per function

  +-----------+------------------+
  | Score     | Interpretation   |
  +-----------+------------------+
  | 1-10      | Simple, good     |
  | 11-20     | Moderate         |
  | 21-50     | Complex          |
  | 50+       | Untestable       |
  +-----------+------------------+

  Code Duplication
  - Percentage of duplicated code blocks
  - Target: < 3%

  Maintainability Index
  - Composite metric (0-100)
  - Higher is better

Quality Tools

• SonarQube: Comprehensive code quality platform
• ESLint: JavaScript linting and style checking
• CodeClimate: Automated code review
• Coverage tools: Istanbul, coverage.py, JaCoCo

Key Takeaways

• Code coverage measures test thoroughness (aim for 70-80%)
• Technical debt should be tracked and managed
• Keep cyclomatic complexity low for maintainability
• Use automated tools to measure and improve quality