Imported from abhijith-dalli/ai-project-harness (templates/.harness/skills/testing/SKILL.md). Install upstream with npx skills add abhijith-dalli/ai-project-harness --skill testing. Copyright stays with the author.

Testing

Comprehensive testing strategy covering unit, integration, and end-to-end tests. Focus on testing behavior, not implementation.

When to Use

• Creating a new test suite
• Improving test coverage
• Reviewing test quality
• Setting up test infrastructure
• Investigating flaky tests

Testing Pyramid

        /\
       /  \        E2E Tests (few, slow, high confidence)
      /    \
     /------\      Integration Tests (moderate, medium speed)
    /        \
   /----------\    Unit Tests (many, fast, focused)

Unit Tests

• Test individual functions/methods in isolation
• Fast execution (milliseconds)
• Mock external dependencies
• High coverage target (80%+)

Integration Tests

• Test component interactions
• Moderate execution (seconds)
• Use real databases/services where practical
• Test data flow between components

End-to-End Tests

• Test complete user workflows
• Slow execution (minutes)
• Use real environments
• Critical paths only

Test Organization

File Structure

tests/
├── unit/
│   ├── models/
│   ├── services/
│   └── utils/
├── integration/
│   ├── api/
│   └── database/
└── e2e/
    └── workflows/

Naming Conventions

• Test files: *_test.py, *.test.js, *.spec.ts
• Test functions: test_describe_scenario, it('should do X when Y')
• Test classes: TestFeatureName, describe('FeatureName')

Coverage Strategy

What to Cover

• All public APIs
• Business logic
• Edge cases and error paths
• Boundary conditions

What NOT to Cover

• Framework boilerplate
• Simple getters/setters
• Third-party library internals
• Configuration files

Flaky Test Management

Detection

• Run tests multiple times in CI
• Track pass/fail rates per test
• Flag tests with <100% pass rate

Resolution

• Identify root cause (timing, ordering, external dependency)
• Fix the test, not the symptom
• Quarantine unfixable flaky tests
• Delete tests that can't be made reliable

Rules

1. Test behavior, not implementation — tests should survive refactors
2. One assertion per test — keep tests focused
3. Tests are documentation — they show how the code should be used
4. Fast feedback — unit tests in milliseconds, not minutes
5. Deterministic — same test, same result, every time