ATM machine (deposits/withdrawals) using OOP

[ndc85430]

Tests are a better way than printing to check your code works. Why better? Because they'll fail if you break something - that way, you're relying on the computer to help you than a human checking the output.

Here are some example test cases:

import unittest

from bank_account import BankAccount

class TestBankAccount(unittest.TestCase):
    def test_a_deposit_increases_the_balance(self):
        account = BankAccount("Jane", "Smith")

        account.deposit(40)

        self.assertEqual(account.balance, 40)

    def test_withdrawing_an_amount_greater_than_the_balance_fails(self):
        account = BankAccount("John", "Smith", starting_balance=0)
        withdrawl_amount = 15
        
        self.assertRaises(ValueError, account.withdraw, withdrawl_amount)

if __name__ == "__main__":
    unittest.main()

Given the BankAccount in Yoriz's post, if I take out the check in withdraw for the amount being greater than the balance, running these gives:

Output:
> python3 test_bank_account.py 
.F
======================================================================
FAIL: test_withdrawing_an_amount_greater_than_the_balance_fails (__main__.TestBankAccount)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "test_bank_account.py", line 17, in test_withdrawing_an_amount_greater_than_the_balance_fails
    self.assertRaises(ValueError, account.withdraw, withdrawl_amount)
AssertionError: ValueError not raised by withdraw

----------------------------------------------------------------------
Ran 2 tests in 0.001s

FAILED (failures=1)

See the docs for the unittest module here.