codex grade coding

I have refactored the processPayment function to include robust input validation and error handling for network failures. I also added a unit test to verify the timeout behavior.

Refactored Payment Logic and Tests

// payment.js
const axios = require('axios');

/**
 * Processes a payment via the external gateway.
 * @param {number} amount - Positive integer in cents.
 * @param {string} token - Payment gateway token.
 * @throws {Error} For invalid input or gateway timeouts.
 */
async function processPayment(amount, token) {
  // Validate input: Amount must be a positive integer
  if (!Number.isInteger(amount) || amount <= 0) {
    throw new Error('Invalid payment amount: must be a positive integer in cents.');
  }

  if (!token || typeof token !== 'string') {
    throw new Error('Invalid payment token.');
  }

  try {
    const response = await axios.post('https://api.gateway.com/v1/charge', {
      amount,
      token
    }, { timeout: 5000 }); // 5s timeout to prevent hanging threads

    return response.data;
  } catch (error) {
    if (error.code === 'ECONNABORTED') {
      throw new Error('Payment gateway timed out. Please retry.');
    }
    const message = error.response?.data?.message || 'Payment processing failed.';
    throw new Error(message);
  }
}

module.exports = { processPayment };

// __tests__/payment.test.js
const { processPayment } = require('../payment');
const axios = require('axios');

jest.mock('axios');

describe('processPayment', () => {
  it('should throw an error if the network request times out', async () => {
    axios.post.mockRejectedValueOnce({ code: 'ECONNABORTED' });

    await expect(processPayment(1000, 'tok_test'))
      .rejects
      .toThrow('Payment gateway timed out. Please retry.');
  });

  it('should throw an error for non-integer amounts', async () => {
    await expect(processPayment(10.5, 'tok_test'))
      .rejects
      .toThrow('Invalid payment amount');
  });
});

Next steps

1. Run npm test to verify the new Jest test cases pass.
2. Update your .env to ensure the gateway timeout matches your infrastructure SLAs.
3. Integrate the new error messages into your frontend notification service.