Unitest in python to deposit amount

Question

I am new to unittesting in python and this is my first unit test. I don't know whether I am doing right or wrong unit test , need some help. I have to test function, in first function i want to test legal deposit and in second function I want to test illegal deposit, like depositing "apple" or "lizard" instead of amount . Since I am new to unit test, I have lot of confusion about it. I read different post,but in my case I am still felling difficult to write unit test for this two functions.

bankaccount.py

class BankAccount():

    def __init__(self):

        self.account_number=0
        self.pin_number=""
        self.balance=0.0
        self.interest=0.0
        self.transaction_list=[]

    def deposit_funds(self, amount):
        self.balance+=amount


    def withdraw_funds(self, amount):

        if amount<=balance:
            self.balance-=amount

---

import unittest

from bankaccount import BankAccount

class TestBankAcount(unittest.TestCase):

    def setUp(self):
        # Create a test BankAccount object
        self.account = BankAccount()

        # Provide it with some property values        
        self.account.balance        = 1000.0

    def test_legal_deposit_works(self):
        # code here to test that depsositing money using the account's
        # 'deposit_funds' function adds the amount to the balance.

     self.assertTrue(100,self.account.deposit_funds(100))


 def test_illegal_deposit_raises_exception(self):
            # code here to test that depositing an illegal value (like 'bananas'
            # or such - something which is NOT a float) results in an exception being
            # raised.

unittest.main()  

Answer 1

You could do something like this:

Have your class raise an error when the type of values provided to deposit_funds does not match the use case.

class BankAccount:

    def __init__(self):

        self.account_number = 0
        self.pin_number = ""
        self.balance = 0.0
        self.interest = 0.0
        self.transaction_list = []

    def deposit_funds(self, amount):
        try:
            self.balance += amount
        except TypeError:
            raise TypeError

    def withdraw_funds(self, amount):
        if amount <= balance:
            self.balance -= amount

Have your tests detect that a TypeError is thrown when that happens.

class TestBankAcount(unittest.TestCase):

    def setUp(self):
        self.test_account = BankAccount()
        self.test_account.balance = 1000.0

    def test_legal_deposit(self):
        expected_balance = 1100.0
        self.test_account.deposit_funds(100.0)
        self.assertEqual(expected_balance, self.test_account.balance)

    def test_illegal_deposit_raises_exception(self):
        # code here to test that depositing an illegal value (like 'bananas'
        # or such - something which is NOT a float) results in an exception being
        # raised.
        with self.assertRaises(TypeError):
            self.test_account.deposit_funds('dummy value')


if __name__ == '__main__':

    unittest.main()