Test Coverage

function divide(a: number, b: number): number {
  if (b === 0) {              // Line 1: COVERED
    throw new Error('Div 0'); // Line 2: NOT COVERED
  }
  return a / b;               // Line 3: COVERED
}

// Test only covers normal case
test('divides numbers', () => {
  expect(divide(10, 2)).toBe(5);
});

// Line Coverage: 66% (2/3 lines)

function getUserStatus(user: User): string {
  if (user.isActive) {     // Branch 1: true (COVERED)
    if (user.isPremium) {  // Branch 2: true (NOT COVERED)
      return 'premium';    // NOT COVERED
    }
    return 'active';       // COVERED
  }
  return 'inactive';       // Branch 1: false (NOT COVERED)
}

// Test only covers active non-premium
test('returns status', () => {
  expect(getUserStatus({ isActive: true, isPremium: false })).toBe('active');
});

// Branch Coverage: 33% (1/3 branches)
// Line Coverage: 60% (3/5 lines)

// auth.ts
export function login(user: string, pass: string) { ... }    // COVERED
export function logout() { ... }                             // COVERED
export function resetPassword(email: string) { ... }         // NOT COVERED
export function changePassword(old: string, new: string) { ... } // NOT COVERED

// Function Coverage: 50% (2/4 functions)

// Single line, multiple statements
const x = 1, y = 2, z = 3;

// Line coverage: 1 line
// Statement coverage: 3 statements

# Test Coverage Gap Analysis

**Generated**: 2026-01-28 14:32:00
**Coverage**: 68% (Target: 80%)
**Files Analyzed**: 247
**Critical Gaps**: 12 files

## Executive Summary

**Overall Coverage**:
- Line Coverage: 68% (Target: 80%) - 12% below
- Branch Coverage: 54% (Target: 75%) - 21% below
- Function Coverage: 71% (Target: 85%) - 14% below

**Risk Assessment**: MEDIUM-HIGH
- 12 critical files under 50% coverage
- 23 high-priority functions untested
- 47 error handling branches untested

## Critical Gaps (Priority 1)

### [GAP-001] Authentication Module
**File**: src/auth/AuthService.ts
**Line Coverage**: 34% (Target: 95%+)
**Branch Coverage**: 22%
**Risk**: CRITICAL

**Untested Code Paths**:
```typescript
// CRITICAL: No tests for password reset flow
async resetPassword(email: string): Promise<void> {
  const user = await this.userRepo.findByEmail(email);
  if (!user) {
    throw new NotFoundError('User not found'); // UNTESTED
  }
  const token = generateResetToken();           // UNTESTED
  await this.emailService.sendResetEmail(       // UNTESTED
    user.email,
    token
  );
}

// CRITICAL: No tests for token expiry
validateResetToken(token: string): boolean {
  const decoded = jwt.verify(token, SECRET);
  if (Date.now() > decoded.exp) {              // UNTESTED
    return false;
  }
  return true;
}

async processPayment(order: Order): Promise<PaymentResult> {
  try {
    const charge = await stripe.charges.create({ // TESTED
      amount: order.total,
      currency: 'usd',
      source: order.paymentToken
    });

    if (charge.status === 'failed') {            // UNTESTED
      await this.handleFailedPayment(order);     // UNTESTED
      throw new PaymentError('Payment failed');
    }

    await this.fulfillOrder(order);              // TESTED
    return { success: true, chargeId: charge.id };
  } catch (error) {
    if (error.code === 'card_declined') {        // UNTESTED
      await this.notifyCardDeclined(order);      // UNTESTED
    }
    throw error;                                 // UNTESTED
  }
}

validateUserData(data: UserInput): ValidationResult {
  const errors: string[] = [];

  if (!data.email || !data.email.includes('@')) {  // Partially tested
    errors.push('Invalid email');
  }

  if (data.password.length < 8) {                  // UNTESTED
    errors.push('Password too short');
  }

  if (!/[A-Z]/.test(data.password)) {              // UNTESTED
    errors.push('Password needs uppercase');
  }

  if (!/[0-9]/.test(data.password)) {              // UNTESTED
    errors.push('Password needs number');
  }

  return { valid: errors.length === 0, errors };
}

async getUser(req: Request, res: Response) {
  try {
    const user = await this.userService.getById(req.params.id);
    res.json(user);                                 // TESTED
  } catch (error) {
    if (error instanceof NotFoundError) {           // UNTESTED
      res.status(404).json({ error: 'Not found' });
    } else if (error instanceof ValidationError) {  // UNTESTED
      res.status(400).json({ error: error.message });
    } else {
      res.status(500).json({ error: 'Server error' }); // UNTESTED
    }
  }
}

Module Coverage Breakdown:

├── src/auth/               34% (CRITICAL - needs work)
├── src/payments/           41% (CRITICAL - needs work)
├── src/users/              62% (below target)
├── src/api/handlers/       59% (below target)
├── src/services/           72% (above target ✓)
├── src/utils/              84% (good ✓)
├── src/database/           91% (excellent ✓)
└── src/components/         77% (good ✓)

Overall: 68%
Target: 80%
Gap: -12%