ChristmasStockingの解法（賄賂が渡っていることの確認）

checkStocking.js

var fs   = require('fs');
var Web3 = require('web3');

var web3 = new Web3('wss://ropsten.infura.io/ws');

var christmasStockingABI     = JSON.parse(fs.readFileSync('./build/contracts/ChristmasStocking.json')).abi;
var christmasStockingAddress = '0x408F56C4541BD00Ec836102d06F7Ee6A2A820678';
var christmasStocking        = new web3.eth.Contract(christmasStockingABI, christmasStockingAddress);

var address = 'your address';
var privkey = 'your priv key';

checkStocking();

async function checkStocking() {

  balance = await christmasStocking.methods.balanceOf(address).call();
  console.log(balance);

  web3.currentProvider.connection.close();
}