Pseudocode for a vending machine "smart contract" in JavaScript

vending-machine-smart-contract.js

/**
 * A pseudo VendingMachine "smart contract" in JavaScript
 *
 * See: https://newline.co
 **/
class VendingMachine {
  constructor() {
    this.price = 50; // 50 cents for any soda
    this.balance = 0; // number of cents paid so far
    this.selection = null; // name of selected drink
    this.inventory = {
      sprite: 3,
      coke: 10,
      'dr pepper': 5
    };
  }

  deposit(amount) {
    this.balance = this.balance + amount;
    this.maybeFinalize();
  }

  makeSelection(name) {
    if (this.inventory[name] && this.inventory[name] > 0) {
      this.selection = name;
      this.maybeFinalize();
    }
  }

  maybeFinalize() {
    if (this.selection && this.balance >= this.price) {
      // subtract balance
      this.balance = this.balance - this.price;

      // subtract inventory
      this.inventory[this.selection] =
        this.inventory[this.selection] - 1;

      this.dispenseDrink(this.selection);

      // clear the selection
      this.selection = null;

      this.refundBalance();
    }
  }

  refundBalance() {
    if (this.balance > 0) {
      const refundAmount = this.balance;
      this.balance = 0;
      this.emitCoins(refundAmount);
    }
  }

  dispenseDrink(name) {
    // ... call hardware to dispense drink
    console.log('Dispensing ' + name);
  }

  emitCoins(amount) {
    if (amount > 0) {
      // ... call hardware to emit coins
      console.log('Refunding ' + amount);
    }
  }
}

const assert = require('assert');

let m = new VendingMachine();

// check initial state
assert(m.inventory.coke === 10);
assert(m.balance === 0);
assert(m.selection === null);

// buy a coke with exact change
m.deposit(25);
assert(m.inventory.coke === 10);
assert(m.balance === 25);

m.deposit(25);
assert(m.balance === 50);

m.makeSelection('coke');

assert(m.inventory.coke === 9);
assert(m.balance === 0);
assert(m.selection === null);

// make a selection first, put in extra money
m.makeSelection('coke');

m.deposit(25);
assert(m.inventory.coke === 9);
assert(m.balance === 25);

m.deposit(100);
assert(m.inventory.coke === 8);
assert(m.balance === 0);

console.log('Done');