---
name: best-practices
description: Testing best practices and principles
parent_skill: leyline:testing-quality-standards
category: infrastructure
estimated_tokens: 200
reusable_by: [pensive:test-review, parseltongue:python-testing]
---

# Testing Best Practices

## Core Principles

1. **Test behavior, not implementation** - Focus on what, not how
2. **One concept per test** - Keep tests focused
3. **Arrange-Act-Assert** - Consistent structure
4. **BDD language** - Given/When/Then for clarity
5. **Fast feedback** - Tests should run quickly

## Naming and Structure

6. **Descriptive names** - `test_user_creation_with_invalid_email_raises_error`
7. **Independent tests** - No shared state between tests
8. **Use fixtures** - Avoid setup duplication

## Boundaries and Coverage

9. **Mock at boundaries** - Only mock external dependencies
10. **Measure coverage** - Aim for meaningful, not just high

## Exit Criteria

- Coverage thresholds documented and understood
- Quality metrics defined and measurable
- Anti-patterns identified and avoided
- Best practices applied consistently