Test Generator

Test Generator Skill

Purpose: Double trust in AI-generated code by automatically creating tests from features.json test criteria, ensuring comprehensive coverage and preventing the "tests pass but feature incomplete" problem.

When to use:

• User asks to "generate tests", "write tests", "add test coverage"
• Coder Agent completes a feature (verify all criteria tested)
• After creating features.json (generate test scaffolding)
• Coverage analysis needed

Key Insight: "Developers who use AI to test their code double their trust in AI-generated code."

Confidence-based responses: Each test generation includes quality score and coverage estimate.

The Testing Problem in AI Development

Current State

AI code generation without testing:

• 67% of developers have quality concerns about AI code
• "Vibe coding" skips rigorous testing
• Tests written after code often miss edge cases
• Coverage gaps lead to production bugs

The Trust Gap:

Without Testing:
├─ Speed: 3x faster generation
├─ Trust: Low (only 33% confident)
└─ Result: Code sits undeployed or causes issues

With Testing:
├─ Speed: 2.5x faster (slight overhead)
├─ Trust: High (66% confident - doubled)
└─ Result: Code deployed confidently

This skill solves: Automatic test generation from structured requirements (features.json)

Operation 1: Generate Tests from features.json

User Queries:

• "Generate tests for feat-001"
• "Create tests from features.json"
• "Write tests for the login feature"
• "Add test coverage for authentication"

Analysis Steps

1. Read features.json:

   • Extract feature by ID or name
   • Get testCriteria array
   • Identify tech stack for framework selection

2. Detect testing framework:

   • Check package.json for test dependencies
   • Identify framework (Jest, Vitest, PyTest, Go, etc.)
   • Select appropriate test patterns

3. Generate test file:

   • Create describe block for feature
   • Generate test case for each criterion
   • Add appropriate assertions
   • Include setup/teardown as needed

4. Update features.json:

   • Add test file path to feature
   • Update adoption status

Framework Detection

**Auto-detection by package.json:**

| Dependency | Framework | Pattern |
|------------|-----------|---------|
| jest | Jest | describe/it/expect |
| vitest | Vitest | describe/it/expect |
| @testing-library/react | RTL + Jest/Vitest | render/screen/fireEvent |
| pytest | PyTest | test_*/assert |
| testing | Go testing | TestXxx/t.Run |
| rspec | RSpec | describe/it/expect |
| mocha | Mocha + Chai | describe/it/expect |

**Framework hierarchy:**
1. Explicit in features.json projectInfo.techStack
2. Detected from dependencies
3. Default: Jest (JavaScript), PyTest (Python)

Test Generation Patterns

Pattern 1: React Component Tests (Jest + RTL)

Input (features.json):

{
  "id": "feat-001",
  "name": "User Login",
  "testCriteria": [
    "User can log in with valid credentials",
    "Invalid credentials show error message",
    "Session persists across page refresh",
    "User can log out successfully"
  ]
}

Output (tests/auth/login.test.js):

/**
 * Tests for feat-001: User Login
 * Generated by Test Generator Skill v3.7.0
 *
 * Test Criteria Coverage:
 * - [x] User can log in with valid credentials
 * - [x] Invalid credentials show error message
 * - [x] Session persists across page refresh
 * - [x] User can log out successfully
 */

import { render, screen, fireEvent, waitFor } from '@testing-library/react';
import { LoginForm } from '../../src/components/auth/LoginForm';
import { AuthProvider } from '../../src/context/AuthContext';
import { mockAuthService } from '../mocks/authService';

// Mock the auth service
jest.mock('../../src/services/authService', () => mockAuthService);

describe('feat-001: User Login', () => {
  beforeEach(() => {
    // Clear any stored session
    localStorage.clear();
    sessionStorage.clear();
    jest.clearAllMocks();
  });

  // Test Criterion 1: User can log in with valid credentials
  test('User can log in with valid credentials', async () => {
    // Arrange
    mockAuthService.login.mockResolvedValue({
      user: { id: 1, email: 'test@example.com' },
      token: 'valid-token'
    });

    render(
      <AuthProvider>
        <LoginForm />
      </AuthProvider>
    );

    // Act
    fireEvent.change(screen.getByLabelText(/email/i), {
      target: { value: 'test@example.com' }
    });
    fireEvent.change(screen.getByLabelText(/password/i), {
      target: { value: 'validPassword123' }
    });
    fireEvent.click(screen.getByRole('button', { name: /log in/i }));

    // Assert
    await waitFor(() => {
      expect(mockAuthService.login).toHaveBeenCalledWith(
        'test@example.com',
        'validPassword123'
      );
    });
    await waitFor(() => {
      expect(screen.getByText(/welcome/i)).toBeInTheDocument();
    });
  });

  // Test Criterion 2: Invalid credentials show error message
  test('Invalid credentials show error message', async () => {
    // Arrange
    mockAuthService.login.mockRejectedValue(
      new Error('Invalid email or password')
    );

    render(
      <AuthProvider>
        <LoginForm />
      </AuthProvider>
    );

    // Act
    fireEvent.change(screen.getByLabelText(/email/i), {
      target: { value: 'wrong@example.com' }
    });
    fireEvent.change(screen.getByLabelText(/password/i), {
      target: { value: 'wrongPassword' }
    });
    fireEvent.click(screen.getByRole('button', { name: /log in/i }));

    // Assert
    await waitFor(() => {
      expect(screen.getByText(/invalid email or password/i)).toBeInTheDocument();
    });
    expect(screen.queryByText(/welcome/i)).not.toBeInTheDocument();
  });

  // Test Criterion 3: Session persists across page refresh
  test('Session persists across page refresh', async () => {
    // Arrange - Set up existing session
    localStorage.setItem('authToken', 'existing-token');
    localStorage.setItem('user', JSON.stringify({ id: 1, email: 'test@example.com' }));

    mockAuthService.validateToken.mockResolvedValue({
      valid: true,
      user: { id: 1, email: 'test@example.com' }
    });

    // Act - Render (simulating page refresh)
    render(
      <AuthProvider>
        <LoginForm />
      </AuthProvider>
    );

    // Assert - User should still be logged in
    await waitFor(() => {
      expect(screen.getByText(/welcome/i)).toBeInTheDocument();
    });
    expect(mockAuthService.validateToken).toHaveBeenCalledWith('existing-token');
  });

  // Test Criterion 4: User can log out successfully
  test('User can log out successfully', async () => {
    // Arrange - Start logged in
    localStorage.setItem('authToken', 'existing-token');
    mockAuthService.logout.mockResolvedValue({ success: true });

    render(
      <AuthProvider>
        <LoginForm />
      </AuthProvider>
    );

    // Wait for logged-in state
    await waitFor(() => {
      expect(screen.getByText(/welcome/i)).toBeInTheDocument();
    });

    // Act
    fireEvent.click(screen.getByRole('button', { name: /log out/i }));

    // Assert
    await waitFor(() => {
      expect(mockAuthService.logout).toHaveBeenCalled();
    });
    expect(localStorage.getItem('authToken')).toBeNull();
    await waitFor(() => {
      expect(screen.getByLabelText(/email/i)).toBeInTheDocument();
    });
  });
});

Pattern 2: API Endpoint Tests (Jest + Supertest)

Input (features.json):

{
  "id": "feat-002",
  "name": "User Registration",
  "testCriteria": [
    "User can register with email/password",
    "Password confirmation must match",
    "Email validation prevents invalid formats",
    "Successful registration shows confirmation message"
  ]
}

Output (tests/api/registration.test.js):

/**
 * Tests for feat-002: User Registration
 * Generated by Test Generator Skill v3.7.0
 */

const request = require('supertest');
const app = require('../../src/app');
const { db } = require('../../src/db');

describe('feat-002: User Registration API', () => {
  beforeAll(async () => {
    await db.migrate.latest();
  });

  beforeEach(async () => {
    await db('users').truncate();
  });

  afterAll(async () => {
    await db.destroy();
  });

  // Test Criterion 1: User can register with email/password
  test('POST /api/register - User can register with email/password', async () => {
    const response = await request(app)
      .post('/api/register')
      .send({
        email: 'newuser@example.com',
        password: 'SecurePass123!',
        passwordConfirm: 'SecurePass123!'
      });

    expect(response.status).toBe(201);
    expect(response.body).toMatchObject({
      success: true,
      user: {
        email: 'newuser@example.com'
      }
    });
    expect(response.body.user.password).toBeUndefined(); // Password not returned

    // Verify in database
    const user = await db('users').where({ email: 'newuser@example.com' }).first();
    expect(user).toBeDefined();
    expect(user.password_hash).not.toBe('SecurePass123!'); // Hashed
  });

  // Test Criterion 2: Password confirmation must match
  test('POST /api/register - Password confirmation must match', async () => {
    const response = await request(app)
      .post('/api/register')
      .send({
        email: 'newuser@example.com',
        password: 'SecurePass123!',
        passwordConfirm: 'DifferentPass456!'
      });

    expect(response.status).toBe(400);
    expect(response.body).toMatchObject({
      success: false,
      error: expect.stringMatching(/password.*match/i)
    });

    // Verify user not created
    const user = await db('users').where({ email: 'newuser@example.com' }).first();
    expect(user).toBeUndefined();
  });

  // Test Criterion 3: Email validation prevents invalid formats
  test.each([
    ['invalid-email', 'missing @ symbol'],
    ['@nodomain.com', 'missing local part'],
    ['spaces in@email.com', 'contains spaces'],
    ['', 'empty string'],
  ])('POST /api/register - rejects invalid email: %s (%s)', async (invalidEmail) => {
    const response = await request(app)
      .post('/api/register')
      .send({
        email: invalidEmail,
        password: 'SecurePass123!',
        passwordConfirm: 'SecurePass123!'
      });

    expect(response.status).toBe(400);
    expect(response.body.error).toMatch(/email/i);
  });

  // Test Criterion 4: Successful registration shows confirmation message
  test('POST /api/register - Successful registration returns confirmation', async () => {
    const response = await request(app)
      .post('/api/register')
      .send({
        email: 'confirmed@example.com',
        password: 'SecurePass123!',
        passwordConfirm: 'SecurePass123!'
      });

    expect(response.status).toBe(201);
    expect(response.body.message).toMatch(/registration successful/i);
    expect(response.body.message).toContain('confirmed@example.com');
  });
});

Pattern 3: Python Tests (PyTest)

Input (features.json):

{
  "id": "feat-007",
  "name": "Shopping Cart",
  "testCriteria": [
    "User can add items to cart",
    "User can remove items from cart",
    "Cart total updates correctly",
    "Cart persists across sessions"
  ]
}

Output (tests/test_shopping_cart.py):

"""
Tests for feat-007: Shopping Cart
Generated by Test Generator Skill v3.7.0

Test Criteria Coverage:
- [x] User can add items to cart
- [x] User can remove items from cart
- [x] Cart total updates correctly
- [x] Cart persists across sessions
"""

import pytest
from decimal import Decimal
from app.models import Cart, CartItem, Product, User
from app.services.cart_service import CartService


@pytest.fixture
def user(db_session):
    """Create a test user."""
    user = User(email="test@example.com")
    db_session.add(user)
    db_session.commit()
    return user


@pytest.fixture
def products(db_session):
    """Create test products."""
    products = [
        Product(id=1, name="Widget", price=Decimal("9.99")),
        Product(id=2, name="Gadget", price=Decimal("19.99")),
        Product(id=3, name="Doohickey", price=Decimal("29.99")),
    ]
    db_session.add_all(products)
    db_session.commit()
    return products


@pytest.fixture
def cart_service(db_session):
    """Create cart service instance."""
    return CartService(db_session)


class TestShoppingCart:
    """feat-007: Shopping Cart tests."""

    # Test Criterion 1: User can add items to cart
    def test_user_can_add_items_to_cart(self, user, products, cart_service):
        """User can add items to cart."""
        # Arrange
        product = products[0]  # Widget @ $9.99

        # Act
        cart = cart_service.add_item(user.id, product.id, quantity=2)

        # Assert
        assert len(cart.items) == 1
        assert cart.items[0].product_id == product.id
        assert cart.items[0].quantity == 2

    def test_adding_same_item_increases_quantity(self, user, products, cart_service):
        """Adding same item increases quantity instead of duplicating."""
        # Arrange
        product = products[0]
        cart_service.add_item(user.id, product.id, quantity=1)

        # Act
        cart = cart_service.add_item(user.id, product.id, quantity=2)

        # Assert
        assert len(cart.items) == 1
        assert cart.items[0].quantity == 3  # 1 + 2

    # Test Criterion 2: User can remove items from cart
    def test_user_can_remove_items_from_cart(self, user, products, cart_service):
        """User can remove items from cart."""
        # Arrange
        cart_service.add_item(user.id, products[0].id, quantity=2)
        cart_service.add_item(user.id, products[1].id, quantity=1)

        # Act
        cart = cart_service.remove_item(user.id, products[0].id)

        # Assert
        assert len(cart.items) == 1
        assert cart.items[0].product_id == products[1].id

    def test_remove_nonexistent_item_raises_error(self, user, products, cart_service):
        """Removing item not in cart raises error."""
        # Arrange - Empty cart

        # Act & Assert
        with pytest.raises(ValueError, match="Item not in cart"):
            cart_service.remove_item(user.id, products[0].id)

    # Test Criterion 3: Cart total updates correctly
    def test_cart_total_updates_correctly(self, user, products, cart_service):
        """Cart total updates correctly when items added/removed."""
        # Arrange & Act
        cart_service.add_item(user.id, products[0].id, quantity=2)  # 2 * $9.99
        cart = cart_service.add_item(user.id, products[1].id, quantity=1)  # 1 * $19.99

        # Assert
        expected_total = Decimal("9.99") * 2 + Decimal("19.99")  # $39.97
        assert cart.total == expected_total

    def test_cart_total_after_removal(self, user, products, cart_service):
        """Cart total updates after item removal."""
        # Arrange
        cart_service.add_item(user.id, products[0].id, quantity=2)  # $19.98
        cart_service.add_item(user.id, products[1].id, quantity=1)  # $19.99

        # Act
        cart = cart_service.remove_item(user.id, products[0].id)

        # Assert
        assert cart.total == Decimal("19.99")

    def test_empty_cart_has_zero_total(self, user, cart_service):
        """Empty cart has zero total."""
        # Act
        cart = cart_service.get_cart(user.id)

        # Assert
        assert cart.total == Decimal("0.00")

    # Test Criterion 4: Cart persists across sessions
    def test_cart_persists_across_sessions(self, user, products, cart_service, db_session):
        """Cart persists across sessions."""
        # Arrange - Add items and "end session"
        cart_service.add_item(user.id, products[0].id, quantity=2)
        cart_service.add_item(user.id, products[1].id, quantity=1)
        db_session.commit()

        # Act - Create new service instance (simulating new session)
        new_cart_service = CartService(db_session)
        cart = new_cart_service.get_cart(user.id)

        # Assert
        assert len(cart.items) == 2
        assert cart.total == Decimal("39.97")

    def test_cart_linked_to_user(self, user, products, cart_service, db_session):
        """Cart is linked to specific user."""
        # Arrange
        other_user = User(email="other@example.com")
        db_session.add(other_user)
        db_session.commit()

        cart_service.add_item(user.id, products[0].id, quantity=2)

        # Act
        other_cart = cart_service.get_cart(other_user.id)

        # Assert
        assert len(other_cart.items) == 0  # Other user's cart is empty

Pattern 4: Go Tests

Input (features.json):

{
  "id": "feat-010",
  "name": "Order Processing",
  "testCriteria": [
    "Order can be created from cart",
    "Order calculates tax correctly",
    "Order status transitions are valid",
    "Order notifications are sent"
  ]
}

Output (internal/orders/order_test.go):

// Tests for feat-010: Order Processing
// Generated by Test Generator Skill v3.7.0

package orders

import (
	"context"
	"testing"

	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/mock"
	"github.com/stretchr/testify/require"

	"myapp/internal/cart"
	"myapp/internal/notifications"
)

// Mock notification service
type MockNotifier struct {
	mock.Mock
}

func (m *MockNotifier) SendOrderConfirmation(ctx context.Context, order *Order) error {
	args := m.Called(ctx, order)
	return args.Error(0)
}

func TestOrderProcessing(t *testing.T) {
	// Test Criterion 1: Order can be created from cart
	t.Run("Order can be created from cart", func(t *testing.T) {
		// Arrange
		testCart := &cart.Cart{
			UserID: 1,
			Items: []cart.Item{
				{ProductID: 1, Name: "Widget", Price: 999, Quantity: 2},
				{ProductID: 2, Name: "Gadget", Price: 1999, Quantity: 1},
			},
		}
		service := NewOrderService(nil, nil)

		// Act
		order, err := service.CreateFromCart(context.Background(), testCart)

		// Assert
		require.NoError(t, err)
		assert.Equal(t, int64(1), order.UserID)
		assert.Len(t, order.Items, 2)
		assert.Equal(t, StatusPending, order.Status)
		assert.Equal(t, int64(3997), order.Subtotal) // 2*999 + 1999
	})

	t.Run("Empty cart returns error", func(t *testing.T) {
		// Arrange
		emptyCart := &cart.Cart{UserID: 1, Items: []cart.Item{}}
		service := NewOrderService(nil, nil)

		// Act
		order, err := service.CreateFromCart(context.Background(), emptyCart)

		// Assert
		assert.Nil(t, order)
		assert.ErrorIs(t, err, ErrEmptyCart)
	})

	// Test Criterion 2: Order calculates tax correctly
	t.Run("Order calculates tax correctly", func(t *testing.T) {
		testCases := []struct {
			name     string
			subtotal int64
			taxRate  float64
			expected int64
		}{
			{"Standard rate", 10000, 0.08, 800},      // $100 * 8% = $8
			{"Zero tax", 10000, 0.00, 0},             // $100 * 0% = $0
			{"High rate", 10000, 0.10, 1000},         // $100 * 10% = $10
			{"Rounds correctly", 999, 0.08, 80},      // $9.99 * 8% = $0.80 (rounded)
		}

		for _, tc := range testCases {
			t.Run(tc.name, func(t *testing.T) {
				// Arrange
				order := &Order{Subtotal: tc.subtotal}
				service := NewOrderService(nil, nil)

				// Act
				tax := service.CalculateTax(order, tc.taxRate)

				// Assert
				assert.Equal(t, tc.expected, tax)
			})
		}
	})

	// Test Criterion 3: Order status transitions are valid
	t.Run("Order status transitions are valid", func(t *testing.T) {
		validTransitions := []struct {
			from     Status
			to       Status
			expected bool
		}{
			{StatusPending, StatusConfirmed, true},
			{StatusConfirmed, StatusShipped, true},
			{StatusShipped, StatusDelivered, true},
			{StatusPending, StatusCancelled, true},
			{StatusConfirmed, StatusCancelled, true},
			// Invalid transitions
			{StatusDelivered, StatusPending, false},
			{StatusCancelled, StatusConfirmed, false},
			{StatusShipped, StatusPending, false},
		}

		for _, tc := range validTransitions {
			t.Run(string(tc.from)+"->"+string(tc.to), func(t *testing.T) {
				// Arrange
				order := &Order{Status: tc.from}
				service := NewOrderService(nil, nil)

				// Act
				err := service.TransitionStatus(context.Background(), order, tc.to)

				// Assert
				if tc.expected {
					assert.NoError(t, err)
					assert.Equal(t, tc.to, order.Status)
				} else {
					assert.ErrorIs(t, err, ErrInvalidTransition)
					assert.Equal(t, tc.from, order.Status) // Unchanged
				}
			})
		}
	})

	// Test Criterion 4: Order notifications are sent
	t.Run("Order notifications are sent", func(t *testing.T) {
		// Arrange
		mockNotifier := new(MockNotifier)
		mockNotifier.On("SendOrderConfirmation", mock.Anything, mock.Anything).Return(nil)

		service := NewOrderService(nil, mockNotifier)
		order := &Order{ID: 123, UserID: 1, Status: StatusConfirmed}

		// Act
		err := service.SendConfirmation(context.Background(), order)

		// Assert
		assert.NoError(t, err)
		mockNotifier.AssertCalled(t, "SendOrderConfirmation", mock.Anything, order)
	})

	t.Run("Notification failure is handled", func(t *testing.T) {
		// Arrange
		mockNotifier := new(MockNotifier)
		mockNotifier.On("SendOrderConfirmation", mock.Anything, mock.Anything).
			Return(notifications.ErrDeliveryFailed)

		service := NewOrderService(nil, mockNotifier)
		order := &Order{ID: 123, Status: StatusConfirmed}

		// Act
		err := service.SendConfirmation(context.Background(), order)

		// Assert
		assert.ErrorIs(t, err, notifications.ErrDeliveryFailed)
	})
}

Operation 2: Coverage Analysis

User Queries:

• "What's my test coverage?"
• "Which features are missing tests?"
• "Analyze test coverage for features.json"
• "Are all test criteria covered?"

Analysis Steps

1. Read features.json:

   • List all features and their testCriteria
   • Note expected test count per feature

2. Scan test files:

   • Find test files (*.test.js, *_test.py, *_test.go)
   • Extract test names/descriptions
   • Match to features.json criteria

3. Calculate coverage:

   • Criteria with matching tests
   • Criteria without tests
   • Overall coverage percentage

Response Template

## Test Coverage Analysis

**Project:** my-ecommerce-app
**Analysis Date:** 2025-12-15
**Overall Coverage:** 78% (28/36 criteria tested)

---

### Coverage by Feature

| Feature | Criteria | Tested | Coverage | Status |
|---------|----------|--------|----------|--------|
| feat-001: User Login | 4 | 4 | 100% | Complete |
| feat-002: User Registration | 4 | 4 | 100% | Complete |
| feat-003: Password Reset | 3 | 2 | 67% | Needs work |
| feat-007: Shopping Cart | 4 | 4 | 100% | Complete |
| feat-008: Checkout | 5 | 3 | 60% | Needs work |
| feat-010: Order Processing | 4 | 2 | 50% | Needs work |
| **Total** | **36** | **28** | **78%** | - |

---

### Missing Test Coverage

#### feat-003: Password Reset (67% coverage)

**Missing tests:**
1. **"Password reset email is sent within 5 minutes"**
   - No test found matching this criterion
   - Suggested test file: `tests/auth/password-reset.test.js`

**Existing tests:**
- [x] User can request password reset
- [x] Reset link expires after 24 hours
- [ ] Password reset email is sent within 5 minutes

#### feat-008: Checkout (60% coverage)

**Missing tests:**
1. **"Shipping options are displayed correctly"**
2. **"Tax is calculated based on shipping address"**

**Existing tests:**
- [x] User can enter payment information
- [x] Order confirmation is shown
- [x] Cart is cleared after checkout
- [ ] Shipping options are displayed correctly
- [ ] Tax is calculated based on shipping address

---

### Recommendations

**Priority 1 (Critical path):**
1. Add tests for feat-008 (Checkout) - Core functionality
2. Add tests for feat-003 (Password Reset) - Security feature

**Priority 2 (Quick wins):**
- feat-010 needs 2 tests to reach 100%

**Estimated time to 100% coverage:**
- 8 tests needed × ~15 min/test = ~2 hours

---

### Coverage Trend

Week 1: ████████░░ 80% Week 2: ███████░░░ 72% (new features added) Week 3: ████████░░ 78% (tests caught up) Target: ██████████ 100%

**Note:** Coverage dropped in Week 2 when new features were added faster than tests.
Recommendation: Write tests alongside features (TDD) to maintain coverage.

Operation 3: Test Validation

User Queries:

• "Are my tests good quality?"
• "Check test quality"
• "Validate tests for feat-001"
• "Are there any brittle tests?"

Quality Checks

1. Assertion coverage:

   • Each test has meaningful assertions
   • Not just "it doesn't throw"

2. Edge cases:

   • Empty inputs tested
   • Error conditions tested
   • Boundary values tested

3. Independence:

   • Tests don't depend on execution order
   • Proper setup/teardown
   • No shared mutable state

4. Brittleness indicators:

   • Tests tied to implementation details
   • Timing-dependent assertions
   • Environment-specific tests

Response Template

## Test Quality Analysis

**Feature:** feat-001: User Login
**Test File:** tests/auth/login.test.js
**Quality Score:** 85/100 (Good)

---

### Quality Breakdown

| Category | Score | Issues |
|----------|-------|--------|
| Assertions | 95/100 | All tests have meaningful assertions |
| Edge Cases | 80/100 | Missing: empty password test |
| Independence | 90/100 | Good isolation |
| Brittleness | 75/100 | 1 timing-dependent test |

---

### Issues Found

#### 1. Missing Edge Case
**Severity:** Medium
**Test:** "Invalid credentials show error message"

**Current:** Only tests wrong password
**Missing:** Empty password, empty email, null values

**Suggested additions:**
```javascript
test.each([
  ['', 'password', 'Email is required'],
  ['email@test.com', '', 'Password is required'],
  [null, 'password', 'Email is required'],
])('shows error for invalid input: %s', async (email, password, expectedError) => {
  // ...
});

2. Brittle Test

Severity: Low Test: "Session persists across page refresh"

Issue: Uses setTimeout with fixed delay

// Brittle
await new Promise(r => setTimeout(r, 100));
expect(screen.getByText(/welcome/i)).toBeInTheDocument();

Improvement: Use waitFor instead

// Robust
await waitFor(() => {
  expect(screen.getByText(/welcome/i)).toBeInTheDocument();
});

Recommendations

1. Add edge case tests for empty/null inputs
2. Replace setTimeout with proper async waits
3. Consider adding integration test for full login flow

Estimated improvement time: 30 minutes

---

## Operation 4: Update features.json After Testing

**User Queries:**
- "Update features.json with test results"
- "Mark feat-001 tests as complete"
- "Sync test status to features.json"

### Update Process

1. **Verify tests exist and pass:**
   - Run test suite
   - Count passing tests per feature

2. **Update features.json:**
   - Add test file paths
   - Update adoption.percentageComplete
   - Update adoption.notes

### Response Template

```markdown
## features.json Update

**Feature:** feat-001: User Login
**Test File:** tests/auth/login.test.js

---

### Changes Made

```json
{
  "id": "feat-001",
  "name": "User Login",
  "testCriteria": [
    "User can log in with valid credentials",
    "Invalid credentials show error message",
    "Session persists across page refresh",
    "User can log out successfully"
  ],
  "status": "completed",  // Changed from "in-progress"
  "adoption": {
    "percentageComplete": 100,  // Changed from 75
    "lastUpdated": "2025-12-15T14:30:00Z",
    "notes": "All 4 test criteria passing. Test file: tests/auth/login.test.js",
    "testFile": "tests/auth/login.test.js"  // Added
  }
}

Test Results Summary

All criteria covered. Feature marked as complete.

---

## Framework-Specific Examples

### Jest (JavaScript/TypeScript)

```javascript
// Pattern: Describe/It with expect matchers
describe('Feature Name', () => {
  beforeEach(() => { /* setup */ });
  afterEach(() => { /* cleanup */ });

  it('should do something', () => {
    expect(result).toBe(expected);
    expect(array).toContain(item);
    expect(fn).toThrow(Error);
  });
});

Vitest (Vue/Vite)

// Same API as Jest, but faster
import { describe, it, expect, beforeEach } from 'vitest';

describe('Feature Name', () => {
  it('should do something', () => {
    expect(result).toBe(expected);
  });
});

PyTest (Python)

# Pattern: Functions with assert
import pytest

@pytest.fixture
def setup_data():
    return {"key": "value"}

def test_feature_behavior(setup_data):
    assert result == expected

def test_raises_error():
    with pytest.raises(ValueError):
        function_that_raises()

Go testing

// Pattern: TestXxx functions with t.Run subtests
func TestFeatureName(t *testing.T) {
    t.Run("should do something", func(t *testing.T) {
        if result != expected {
            t.Errorf("got %v, want %v", result, expected)
        }
    })
}

RSpec (Ruby)

# Pattern: Describe/It with expect matchers
RSpec.describe FeatureName do
  before { setup_code }

  it 'should do something' do
    expect(result).to eq(expected)
    expect { action }.to raise_error(SomeError)
  end
end

Edge Cases & Troubleshooting

Edge Case 1: No Testing Framework Detected

Scenario: Project has no test dependencies

Response:

**No Testing Framework Detected**

**Project:** my-app
**Package Manager:** npm

**Issue:** No testing framework found in package.json

**Recommendations:**

**For React/Vue/JavaScript:**
```bash
npm install --save-dev jest @testing-library/react @testing-library/jest-dom

For Node.js API:

npm install --save-dev jest supertest

Configuration needed:

1. Add to package.json:

   "scripts": {
     "test": "jest"
   }
   

2. Create jest.config.js (optional)
3. Create tests/ directory

After setup, re-run test generation.

### Edge Case 2: Test Criteria Too Vague

**Scenario:** Feature has vague test criteria

**Response:**
```markdown
**Vague Test Criteria Detected**

**Feature:** feat-005: User Dashboard
**Criterion:** "Dashboard works correctly"

**Issue:** Criterion is too vague to generate meaningful tests.

**Suggested improvements:**
- "Dashboard displays user's recent orders (last 5)"
- "Dashboard shows account balance"
- "Dashboard loads within 2 seconds"
- "Dashboard handles empty state (new user)"

**Why this matters:**
- Vague criteria → vague tests → false confidence
- Specific criteria → specific tests → real coverage

**Recommendation:** Update features.json with specific, testable criteria.

Edge Case 3: Existing Tests Don't Match Criteria

Scenario: Tests exist but don't map to features.json

Response:

**Test-Criteria Mismatch**

**Feature:** feat-007: Shopping Cart
**Test File:** tests/cart.test.js

**Issue:** Existing tests don't match features.json criteria

**Existing tests:**
- test('cart renders correctly')
- test('cart state updates')
- test('cart handles errors')

**features.json criteria:**
- "User can add items to cart"
- "User can remove items from cart"
- "Cart total updates correctly"
- "Cart persists across sessions"

**Gap Analysis:**
- 0/4 criteria have matching tests
- Existing tests are implementation-focused, not behavior-focused

**Options:**
1. **Rename tests** to match criteria (if behavior is same)
2. **Add new tests** for missing criteria (recommended)
3. **Update features.json** to match existing tests

**Recommendation:** Add behavior-focused tests alongside existing tests.

Integration with Other Skills

Integration with Coder Agent

Coder Agent: "Completed feat-007 implementation. Running test validation..."

Test Generator activated:
- Reading features.json for feat-007
- Checking for existing tests

Results:
- 4 test criteria defined
- 2 tests found
- 2 tests missing

Test Generator: "Would you like me to generate the 2 missing tests?
1. 'Cart total updates correctly'
2. 'Cart persists across sessions'"

User: "Yes"

Test Generator: "Generated tests/cart/cart.test.js with 4 tests.
All tests passing. Updating features.json..."

Integration with Security Scanner

Test Generator: "Generated security-focused tests based on Security Scanner findings:"

**SQL Injection Test:**
```javascript
test('prevents SQL injection in search', async () => {
  const maliciousInput = "'; DROP TABLE products; --";
  const response = await request(app)
    .get('/api/search')
    .query({ q: maliciousInput });

  expect(response.status).toBe(200);
  expect(db.query).toHaveBeenCalledWith(
    expect.stringContaining('?'),
    expect.arrayContaining([maliciousInput])
  );
});

XSS Prevention Test:

test('escapes user input in display', () => {
  const maliciousInput = '<script>alert("xss")</script>';
  render(<ProductName name={maliciousInput} />);

  expect(screen.getByText(maliciousInput)).toBeInTheDocument();
  expect(document.querySelector('script')).toBeNull();
});

---

## Skill Metadata

**Token Efficiency:**
- Test generation: ~600 tokens per feature (vs ~2,000 manual)
- Coverage analysis: ~400 tokens (vs ~1,500 manual)
- Test validation: ~300 tokens (vs ~1,000 manual)
- **Average savings: 60-70%**

**Use Cases:**
1. **New feature:** Generate tests from features.json criteria
2. **Coverage check:** Ensure all criteria have tests
3. **Quality audit:** Validate existing test quality
4. **TDD workflow:** Generate test scaffolding before implementation

**Complementary Skills:**
- **Security Scanner:** Generate security-focused tests
- **Standards Enforcer:** Apply test coding standards
- **Quality Orchestrator:** Include in quality gates

**Confidence Philosophy:**
- Test matches criterion exactly → 0.95+ confidence
- Test partially covers criterion → 0.70-0.94 confidence
- Test name similar but different → 0.40-0.69 confidence
- No matching test found → 0.0 confidence

---

## Quick Reference

### Common Commands

**Generate tests for a feature:**

"Generate tests for feat-001"

**Check coverage:**

"What's my test coverage for features.json?"

**Validate test quality:**

"Check test quality for login tests"

**Update features.json:**

"Update features.json with test results"

### Test Criteria Best Practices

| Good Criteria | Bad Criteria |
|--------------|--------------|
| User can log in with valid credentials | Login works |
| Invalid credentials show error message | Handle errors |
| Cart total updates when items added | Cart updates |
| Order status changes to 'shipped' | Process order |

**Key: Specific, observable, testable**