Test Coverage Report Skill

Generate and analyze test coverage reports.

When to Use

• After running tests
• Before creating PR
• Identifying untested code
• Improving test coverage

Usage

Python Coverage

# Run tests with coverage
pytest --cov=src --cov-report=html tests/

# View report
open htmlcov/index.html

# Terminal report
pytest --cov=src --cov-report=term-missing tests/

Mojo Coverage (Future)

# When Mojo coverage tools available
mojo test --coverage tests/

Coverage Metrics

Line Coverage

Percentage of lines executed:

src/module.mojo
  Lines: 45/50 (90%)
  Missing: 12, 18, 23, 35, 41

Branch Coverage

Percentage of decision branches taken:

Branches: 8/10 (80%)
Missing branches: 12->15, 18->20

Coverage Goals

• Minimum: 80% line coverage
• Target: 90% line coverage
• Critical paths: 100% coverage
• Edge cases: Must be tested

Coverage Report

Coverage Report
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

File                Lines    Missing    Coverage
────────────────────────────────────────────────
src/tensor.mojo       150         5      96.7%
src/nn.mojo          200        30      85.0%
src/utils.mojo        50        10      80.0%
────────────────────────────────────────────────
TOTAL                400        45      88.8%

Critical paths: 100% ✅
Minimum coverage: 80% ✅
Target coverage: 90% ❌

Improving Coverage

1. Identify gaps: Find uncovered lines
2. Add tests: Write tests for gaps
3. Re-run: Verify coverage improved
4. Repeat: Until targets met

CI Integration

- name: Test Coverage
  run: |
    pytest --cov=src --cov-report=xml
    codecov -f coverage.xml

See phase-test-tdd for test generation.