gistfile1.txt

const paymentAPI = {
  async chargeCard(amount, cardNumber) {
    // In production, this calls a real payment processor
    await new Promise(resolve => setTimeout(resolve, 100));
    
    if (cardNumber.startsWith('4')) {
      return { success: true, transactionId: 'txn_123', amount };
    }
    throw new Error('Card declined');
  }
};

async function processPayment(amount, cardNumber) {
  try {
    const result = await paymentAPI.chargeCard(amount, cardNumber);
    return {
      status: 'success',
      transactionId: result.transactionId,
      amount: result.amount
    };
  } catch (error) {
    return {
      status: 'failed',
      error: error.message
    };
  }
}


describe('processPayment', () => {
  // EXERCISE 1: Test that processPayment handles a successful payment correctly
  // without actually calling a payment processor.
  it('should handle successful payment', async () => {
    // TODO: Spy/mock paymentAPI.chargeCard
    
    const result = await processPayment(50, '4111111111111111');
    
    // TODO: Verify chargeCard was called with (50, '4111111111111111')
    
    // TODO: Verify result status is 'success'
    
    // TODO: Verify result has transactionId 'txn_456'
    
    // TODO: Restore the spy
  });
  
  // EXERCISE 2: You want to test that processPayment handles a failed payment correctly
  // by throwing an error without actually failing a real payment
  it('should handle payment failure', async () => {
    // TODO: Spy on paymentAPI.chargeCard and mock it to reject with:
    // new Error('Insufficient funds')
    // const chargeSpy = jest.spyOn(...).mockRejectedValue(...)
    
    const result = await processPayment(1000, '4111111111111111');
    
    // TODO: Verify chargeCard was called
    
    // TODO: Verify result status is 'failed'
    
    // TODO: Verify result error is 'Insufficient funds'
    
    // TODO: Restore the spy
  });
});