Writing Integration Tests

test('payment processing integration', async () => {
  const order = await createOrder({
    items: [{ id: 'item1', quantity: 2 }],
    total: 100
  });
  
  const paymentResult = await processPayment({
    orderId: order.id,
    amount: order.total,
    token: 'valid_token'
  });
  
  expect(paymentResult.status).toBe('success');
  
  const updatedOrder = await Order.findById(order.id);
  expect(updatedOrder.status).toBe('paid');
  
  const invoice = await Invoice.findOne({ orderId: order.id });
  expect(invoice).toBeDefined();
});