var redsys = new Redsys({
  "merchant": {
    "code": "MERCHANT_CODE",
    "terminal": "1",
    "titular": "TITULAR",
    "name": "NAME",
    "secret": "qwertyasdf0123456789"
  },
  "language": "auto",
  "test": true
});

form_data = redsys.create_payment({
  total: ORDER_TOTAL,
  currency: "EUR",
  order: "ORDER ID",
  description: "ORDER DESCRIPTION",
  data: "CART DATA",
  transaction_type: 0,
  redirect_urls: {
    callback: "CALLBACK URL",
    return_url: "OK URL",
    cancel_url: "KO URL"
  }
});

grunt test

Number: 4548812049400004
Date: 12/12
CVV2: 123
CIP: 123456