Add extra test: Prevent assigning value to `balance` property in "Bank Account" exercise

The “Bank Account” exercise should have a test case that raises ValueError when directly assigning value to balance property.

Below code(many user submissions have similar code) passes all the current test cases:

class BankAccount {
  constructor() {
    this.isActive = false
    this._balance
  }

  open() {
    if (this.isActive) throw new ValueError()
    this.isActive = true
    this.balance = 0
  }

  close() {
    if (this.isActive) this.isActive = false
    else throw new ValueError()
  }

  deposit(amt) {
    if (amt < 0) throw new ValueError()
    this.balance += amt
  }

  withdraw(amt) {
    if (amt < 0 || amt > this.balance) throw new ValueError()
    this.balance -= amt
  }

  get balance() {
    if (!this.isActive) throw new ValueError()
    return this._balance
  }

  set balance(amt) {
    this._balance = amt
  }
}

class ValueError extends Error {
  constructor() {
    super('Bank account error');
  }
}

There’s no test case that raises error on doing

let ba = new BankAccount()
ba.balance = 100 // Expected ValueError

[kshivakumar]

That’s a good idea, raising a PR.

[junedev]

We circled back to the no setter vs. setter with ValueError decision. Let me propose a compromise before I ask a senior maintainer to make a call here.

What about the new test just checks that an error is thrown when trying to assign a balance but does not require a specific error type, just any Error. That way no setter and a setter that throws an error would both pass the tests which makes sense since both are valid solutions to the problem. WDYT?