tdd-with-agents

Files (1)

• SKILL.md

SKILL.md (first lines)

# TDD with Agents

Enforce RED → GREEN → REFACTOR cycle across all implementation agents. Includes advanced testing patterns for E2E, load, mutation, and contract testing.

---

## Core Principle

> **Write the test FIRST. Watch it fail. Write minimal code to pass. Refactor with confidence.**

---

## TDD Cycle (RED → GREEN → REFACTOR)

### RED — Write Failing Test
- Write test for the behavior you want
- Run it → **must fail** (confirms test works)
- Test should be specific: one assertion per test

### GREEN — Make It Pass
- Write **minimal** code to pass the test
- No extra features, no premature optimization
- If it feels hard → design problem; refactor test

### REFACTOR — Improve Without Breaking
- Clean up code while tests stay green
- Extract functions, rename, remove duplication
- Tests are your safety net

---

## Testing by Layer

### Backend (Hermes)
```python
# Unit: service logic
def test_calculate_discount_applies_percentage():
    result = calculate_discount(100, 10)
    assert result == 90.0

# Integration: API endpoint
def test_get_user_returns_404_for_missing():
    response = client.get("/users/nonexistent")
    assert response.status_code == 404

# Database: repository
def test_user_repository_saves_and_retrieves():
    repo.save(User(id="1", name="Test"))
    assert repo.find("1").name == "Test"
```

### Frontend (Aphrodite)
```typescript
// Test behavior, not implementation
test('shows error message on invalid form', async () => {
  render(<LoginForm />)
  await userEvent.click(screen.getByText('Submit'))
  expect(screen.getByText('Email is required')).toBeInTheDocument()
})
```

### Database (Demeter)
```python
def test_migration_creates_users_table():
    alembic upgrade(head)
    assert inspector.has_table('users')

def test_migration_rollback_drops_table():
    alembic upgrade(head)
    alembic downgrade(-1)
    assert not inspector.has_table('users')
```

---

## Advanced Testing Patterns

### E2E Testing (Playwright)
```typescript
test('user can complete full signup flow', async ({ page }) => {
  await page.goto('/signup')
  await page.fill('[name="email"]', 'test@example.com')
  await page.fill('[name="password"]', 'secure123')
  await page.click('button[type="submit"]')
  await expect(page.locator('.welcome-banner')).toBeVisible()
})
```

### Load Testing (k6/Locust)
```javascript
// k6 script
export const options = { vus: 50, duration: '30s' }
export default function () {
  http.get('http://localhost:8000/api/users')
}
```

### Contract Testing (Pact)
```python
# Provider verifies consumer contract
@pact.verify_provider
def test_provider_satisfies_consumer_contract():
    # Verify all interactions from pact file
    pass
```

### Mutation Testing
- Mutate source code (change `>` to `<`, remove conditions)
- Run tests → should fail (mutation killed)
- If tests pass → test is weak; improve it

### Visual Regression
```typescript
test('homepage looks the same', async ({ page }) => {
  await page.goto('/')
  await expect(page).toHaveScreenshot('homepage.png')
})
```

From ils15/pantheon-legacy, MIT.

More from ils15/pantheon-legacy