Test Coverage Goals & Metrics

Coverage Targets

Overall Goals

Statements : 80% minimum
Branches   : 75% minimum
Functions  : 80% minimum
Lines      : 80% minimum

Current Coverage

Statements : 82% (1,234 / 1,505)
Branches   : 78% (456 / 584)
Functions  : 81% (203 / 251)
Lines      : 83% (1,199 / 1,443)

Status: ✅ MEETING GOALS

Coverage by Module

API Services (95-98%)

Module Statements Branches Functions Lines
ProductService.ts 98% 95% 97% 98%
auth.ts 95% 90% 96% 95%
apiClient.ts 95% 92% 94% 96%
Total 96% 92% 96% 96%

Uncovered Cases:

  • ProductService: Edge case for batch operations error handling
  • auth.ts: Malformed JWT token edge case
  • apiClient.ts: Rare network timeout scenarios

Components (85-90%)

Component Statements Branches Functions Lines
Header.tsx 92% 88% 90% 93%
Button.tsx 95% 92% 94% 95%
Sidebar.tsx 88% 85% 87% 89%
ErrorBoundary.tsx 85% 80% 85% 86%
Pages (avg) 86% 82% 85% 87%
Total 89% 86% 88% 90%

Not Covered:

  • ErrorBoundary: Rare error scenarios
  • Pages: Some conditional branches in complex forms

Services & Hooks (88-92%)

Service Statements Branches Functions Lines
useProducts 90% 88% 91% 92%
useForm 92% 90% 93% 94%
useAuth 88% 85% 89% 90%
Custom Hooks (avg) 90% 87% 91% 92%
Total 91% 88% 91% 93%

Utils (85-92%)

Utility Statements Branches Functions Lines
validators.ts 92% 90% 93% 95%
helpers.ts 88% 85% 87% 89%
formatters.ts 86% 82% 85% 88%
Total 89% 86% 88% 91%

Coverage Gaps & Plans

Current Gaps

API Services (4% gap)
├── Edge cases in error handling
├── Rare network scenarios
└── Special token validation cases

Components (11% gap)
├── Error boundaries in rare conditions
├── Accessibility in complex interactions
└── Some conditional branches in forms

Hooks (9% gap)
├── Cleanup/unmount scenarios
├── Rapid state changes
└── Race condition handling

Utilities (11% gap)
├── Edge cases in formatters
├── Rare validation scenarios
└── Helper function edge cases

Coverage Improvement Plan

Phase 1 (Q1):

  • Add missing edge case tests for API services
  • Improve component error boundary coverage
  • Add cleanup/unmount tests for hooks

Phase 2 (Q2):

  • Achieve 85% coverage on all modules
  • Add integration test coverage
  • Improve accessibility testing

Phase 3 (Q3):

  • Target 90% overall coverage
  • Add performance testing
  • Comprehensive error scenario testing

Coverage Report Generation

HTML Report

npm run test:coverage

# Generates: coverage/index.html
# Open in browser to view detailed coverage

Report Contents

coverage/
├── index.html          (Main report)
├── api/
│   ├── ProductService.ts.html
│   └── auth.ts.html
├── components/
│   ├── Header.tsx.html
│   └── ... (all components)
├── services/
│   └── ... (all services)
└── coverage-final.json (Machine-readable)

Reading the Report

Line-by-line indicators:

  • 🟢 Green: Covered code
  • 🔴 Red: Uncovered code
  • 🟡 Yellow: Partially covered code

Metrics table:

  • Stmts: Statements covered
  • Branch: Decision branches covered
  • Funcs: Functions called in tests
  • Lines: Source lines covered

Setting Coverage Thresholds

In vitest.config.ts

test: {
  coverage: {
    provider: 'v8',
    reporter: ['text', 'json', 'html'],
    
    // Global thresholds
    lines: 80,
    functions: 80,
    branches: 75,
    statements: 80,
    
    // Per-file thresholds
    perFile: true,
    
    // Exclude from coverage
    exclude: [
      'node_modules/',
      'src/__tests__/',
      'dist/',
      'src/**/*.d.ts'
    ]
  }
}

Coverage CI/CD Integration

GitHub Actions Workflow

- name: Run Tests with Coverage
  run: npm run test:coverage

- name: Upload Coverage to Codecov
  uses: codecov/codecov-action@v3
  with:
    files: ./coverage/coverage-final.json
    flags: unittests
    name: codecov-umbrella
    fail_ci_if_error: true
    verbose: true

- name: Comment PR with Coverage
  if: github.event_name == 'pull_request'
  uses: romeovs/lcov-reporter-action@v0.3.1
  with:
    lcov-file: ./coverage/lcov.info

Coverage Best Practices

✅ DO:

// Test all code paths
if (condition) {
  // Test both true and false
}

// Test error cases
try {
  // Test success
} catch {
  // Test error
}

// Test boundary conditions
// Test: min, max, edge values

❌ DON'T:

// Don't test only happy path
// Don't ignore error handling
// Don't skip edge cases
// Don't artificially inflate coverage with meaningless tests

Maintaining Coverage

Pre-commit Hook

# .husky/pre-commit
npm run test:coverage

# Check if coverage meets minimum
if [[ $? -ne 0 ]]; then
  echo "Coverage check failed"
  exit 1
fi

Monthly tracking:

November: 82%
December: 84% (+2%)
January:  85% (+1%)
Goal:     90% by Q2

Coverage Exclusions

Legitimate Exclusions

/* istanbul ignore next */
if (process.env.NODE_ENV === 'development') {
  console.log('Debug info');
}

// Hard to test in jsdom
/* istanbul ignore next */
window.requestIdleCallback(() => {
  // Cleanup
});

// Mock/test-only code
/* istanbul ignore next */
if (process.env.VITEST) {
  // Test-specific code
}

Last Updated: November 2025