| name | testing-strategy |
| description | Test pyramid, coverage targets, and test patterns (unit/integration/E2E). TRIGGER when: planning tests, writing test code, or reviewing coverage. SKIP: quality-gate scoring of plans (use quality-validation); security testing (use security-review-checklists). (Examples use common runners such as pytest and vitest.) |
Testing Strategy Skill
Purpose
Comprehensive testing guidelines including test pyramid, coverage targets, and test patterns.
Auto-Invoke Triggers
- Planning test strategy
- Writing unit/integration tests
- Reviewing test coverage
- Setting up test infrastructure
Test Pyramid
/\
/ \ E2E Tests (10%)
/----\ - Critical user flows
/ \ - Slow, expensive
/--------\ Integration Tests (20%)
/ \ - API tests, DB tests
/------------\ - Medium speed
/ \ Unit Tests (70%)
/----------------\ - Fast, isolated
- Business logic
Distribution Guidelines
| Type | Percentage | Focus |
|---|
| Unit | 70% | Business logic, utilities |
| Integration | 20% | API, database, services |
| E2E | 10% | Critical user journeys |
Coverage Targets
| Metric | Minimum | Target |
|---|
| Line coverage | 70% | 80% |
| Branch coverage | 60% | 70% |
| Critical paths | 90% | 100% |
What to Cover
- All public methods
- Business logic
- Edge cases
- Error handling
- Integration points
What NOT to Cover
- Generated code
- Simple getters/setters
- Framework code
- Third-party libraries
Unit Testing
Principles
- Test one thing per test
- Tests should be fast (< 100ms)
- Tests should be isolated
- Tests should be deterministic
- No external dependencies
AAA Pattern
Arrange - Set up test data and mocks
Act - Execute the method under test
Assert - Verify the expected outcome
Naming Convention
{Method}_{Scenario}_{ExpectedResult}
CreateUser_ValidData_ReturnsUserId
CreateUser_DuplicateEmail_ThrowsConflict
CalculateTotal_EmptyCart_ReturnsZero
Test Categories
| Category | Purpose | Example |
|---|
| Happy path | Normal operation | Valid user creation |
| Edge case | Boundary conditions | Empty input, max length |
| Error case | Failure scenarios | Invalid data, not found |
Integration Testing
Scope
- API endpoints
- Database operations
- External service calls
- Message queues
Best Practices
- Use test containers or in-memory DB
- Seed known test data
- Clean up after each test
- Mock external services
- Test full request/response cycle
API Test Checklist
E2E Testing
When to Use
- Critical user journeys
- Payment flows
- Authentication flows
- Multi-step workflows
Best Practices
- Test user perspective, not implementation
- Use stable selectors (data-testid)
- Handle async operations properly
- Keep tests independent
- Use page object pattern
Critical Paths to Test
- User registration/login
- Main feature workflow
- Payment/checkout
- Error recovery flows
Test Data Management
Strategies
| Strategy | Use Case |
|---|
| Fixtures | Static test data |
| Factories | Dynamic test data |
| Builders | Complex objects |
| Seeders | Database state |
Rules
- Use realistic but fake data
- Never use production data
- Reset state between tests
- Use faker libraries for variety
Mocking Guidelines
When to Mock
- External services (APIs, databases)
- Time-dependent operations
- Random values
- Expensive operations
When NOT to Mock
- Simple value objects
- The code under test
- Everything (over-mocking)
Mock Types
| Type | Purpose |
|---|
| Stub | Return canned responses |
| Mock | Verify interactions |
| Spy | Record calls, pass through |
| Fake | Simplified implementation |
Test Organization
File Structure
tests/
├── unit/
│ ├── services/
│ └── utils/
├── integration/
│ ├── api/
│ └── db/
├── e2e/
├── fixtures/
└── conftest.py / setup.ts
Naming
- Test files:
{module}_test.py or {module}.test.ts
- Match source structure
- Group related tests in describe/class
CI/CD Integration
Pipeline Stages
- Unit tests - Run on every commit
- Integration tests - Run on PR/merge
- E2E tests - Run on deploy to staging
Quality Gates
| Gate | Requirement |
|---|
| Unit tests | 100% pass |
| Coverage | > 70% |
| Integration | 100% pass |
| E2E (critical) | 100% pass |
Performance Testing
Types
| Type | Purpose |
|---|
| Load | Expected traffic |
| Stress | Breaking point |
| Soak | Memory leaks |
| Spike | Sudden traffic |
Metrics to Measure
- Response time (p50, p95, p99)
- Throughput (requests/second)
- Error rate
- Resource usage
Best Practices
DO
- Write tests before fixing bugs
- Test behavior, not implementation
- Keep tests simple and readable
- Run tests frequently
- Maintain test code quality
- Use meaningful assertions
DON'T
- Test private methods directly
- Write flaky tests
- Skip tests temporarily (delete instead)
- Test external systems
- Ignore slow tests
- Copy-paste test code
Test Quality Checklist
