Hack Reactor CashAmount Interview Prep

CashAmount

class CashAmount {
  constructor (amount) {
    this.pennyCount = 0;
    this.addDoubleAmount(amount);
  }

  totalAsPennies () {
    return this.pennyCount;
  }
  totalInPennies () {
    return this.totalAsPennies();
  }

  addDoubleAmount (double) {
    var roundedPennyCount = Math.floor(double * 100);
    this.pennyCount += roundedPennyCount;
  }

  quantityOfEachDenomination () {
    var denominations = [[10000, 'hundreds'], [5000, 'fifties'], [2000, 'twenties'], [1000, 'tens'], [500, 'fives'], [100, 'ones'], [25, 'quarters'], [10, 'dimes'], [5, 'nickels'], [1, 'pennies']];
    var amount = this.pennyCount; // Since we need a modifiable copy of this.pennyCount to work with
    var denominationAmounts = {};
    for (var i = 0; i < denominations.length; i++) {
      denominationAmounts[denominations[i][1]] = 0;
      while (amount >= denominations[i][0]) {
        amount -= denominations[i][0];
        denominationAmounts[denominations[i][1]]++;
      }
    }
    return denominationAmounts;
  }

  toDouble () {
    return this.pennyCount / 100;
  }

  toDoubleString () {
    return this.toDouble().toString();
  }
}




class TestSuite {
  runTests () {
    this.passed = 0;
    this.failed = 0;
    var cash = new CashAmount(10.50);
    this.expect(cash.totalInPennies(), 1050, 'totalInPennies() returns correct value');
    cash.addDoubleAmount(29.33);
    this.expect(cash.totalAsPennies(), 3983, 'addDoubleAmount() properly mutates CashAmount value');
    this.expect(cash.toDouble(), 39.83, 'toDouble() returns correct value');
    this.expect(cash.toDoubleString(), '39.83', 'toDoubleString() returns correct value');
    cash = new CashAmount(967.93);
    this.expectObj(cash.quantityOfEachDenomination(), {
      'hundreds': 9,
      'fifties': 1,
      'twenties': 0,
      'tens': 1,
      'fives': 1,
      'ones': 2,
      'quarters': 3,
      'dimes': 1,
      'nickels': 1,
      'pennies': 3
    }, 'quantityOfEachDenomination() returns correct values');
    cash = new CashAmount(0.10);
    cash.addDoubleAmount(0.20);
    this.expect(cash.totalInPennies(), 30, 'Should retain floating-point precision when adding amounts less than a dollar');

    if (this.passed + this.failed > 0) {
      if (this.failed === 0) {
        console.log('All ' + this.passed + ' tests passed');
      } else {
        console.log('Passed ' + this.passed + ' tests');
        console.log('Failed ' + this.failed + ' tests');
      }
    } else {
      console.log('No tests were run');
    }
  }

  expect (val1, val2, testName) {
    if (val1 === val2) {
      this.passed++;
    } else {
      console.error('Failed: ' + testName);
      this.failed++;
    }
  }
  expectObj (val1, val2, testName) {
    if (JSON.stringify(val1) === JSON.stringify(val2)) {
      this.passed++;
    } else {
      console.error('Failed: ' + testName);
      this.failed++;
    }
  }
}

new TestSuite().runTests();