Python creates a unit test in a separate program that tests the class.

class BankAccount : ## Constructs a bank account with a given balance. # @param initialBalance the initial account balance (default = 0.0) # def __init__(self, initialBalance = 0.0) : self._balance = initialBalance

## Deposits money into this account. # @param amount the amount to deposit # def deposit(self, amount) : self._balance = self._balance + amount

## Makes a withdrawal from this account, or charges a penalty if # sufficient funds are not available. # @param amount the amount of the withdrawal # def withdraw(self, amount) : PENALTY = 10.0 if amount > self._balance : self._balance = self._balance - PENALTY else : self._balance = self._balance - amount

## Adds interest to this account. # @param rate the interest rate in percent # def addInterest(self, rate) : amount = self._balance * rate / 100.0 self._balance = self._balance + amount

## Gets the current balance of this account. # @return the current balance # def getBalance(self) : return self._balance