fix banking system

Author: despadam

13_object_oriented_programming_advanced.ipynb

@@ -722,52 +722,46 @@
    "source": [
     "### Exercise: Banking System\n",
     "\n",
-    "In this exercise, we will implement a very simple banking system where there are two different types of accounts: **Salary Accounts** and **Savings Accounts**.\n",
+    "In this exercise, we will implement a simple banking system where there are two different types of accounts: **Salary Accounts** and **Savings Accounts**.\n",
     "\n",
     "We assume the following Classes:\n",
     "\n",
     "**Account**:\n",
     "\n",
-    "An abstract base class representing a generic bank account with attributes `account_number` and `balance` and abstract methods `credit()` and `get_balance()`.\n",
+    "An abstract base class representing a generic bank account with attributes `account_number` and `balance`, and abstract methods `credit()` and `get_balance()`.\n",
     "It should also contain the method `debit()`, which, if funds are sufficient, should subtract a given amount (parameter) from the account balance.\n",
     "Method `debit()` should be common for all derived classes.\n",
+    "When an Account is created it should always be initialized with **balance equal to 0**.\n",
     "\n",
     "**SalaryAccount**:\n",
     "\n",
     "A derived class representing a salary account that contains an additional attribute for `tax_rate` and **overrides** methods `credit()` and `get_balance()`.\n",
-    "Method `credit()` should set the balance as the `gross_salary` after applying the `tax_rate` to it.\n",
+    "Method `credit()` should update the `balance` with the **net salary**, so after applying taxes.\n",
     "Method `get_balance()` should simply return the account balance.\n",
     "\n",
     "**SavingsAccount**:\n",
     "\n",
-    "A derived class representing a savings account that contains additional attributes for `interest_rate` and the account's `creation_year`, plus **overrides** methods `credit()` and `get_balance()`.\n",
+    "A derived class representing a savings account that contains an additional attribute for `interest_rate` and **overrides** methods `credit()` and `get_balance()`.\n",
     "Method `credit()` should simply add the given amount to the current balance.\n",
-    "Method `get_balance()` should return the account balance plus interest, based on the `interest_rate` and the `years_passed` from the account's creation.\n",
+    "Method `get_balance()` should return the account balance including interest.\n",
     "\n",
     "<div class=\"alert alert-block alert-warning\">\n",
     "    <h4><b>Question</b></h4>\n",
     "    Using <strong>abstraction</strong> in Python, create a banking system based on the entities mentioned above.\n",
     "    <ul>\n",
     "      <li>\n",
-    "        <strong>Initialize Accounts:</strong>\n",
-    "        <p>Create a Salary Account and a Savings Account with an initial balance of 0 in each.</p>\n",
+    "        <p>Define classes <code>Account</code>, <code>SalaryAccount</code> and <code>SavingsAccount</code>.</p>\n",
     "      </li>\n",
     "      <li>\n",
-    "        <strong>Update Salary Account:</strong>\n",
-    "        <p>Add an amount represented by <code>gross_salary</code> to the Salary Account's balance.</p>\n",
+    "        <p>Create an instance of <code>SalaryAccount</code>, passing as parameters any <code>account_number</code> that you like and the <code>tax_rate</code> that is given in the solution function's parameters.</p>\n",
     "      </li>\n",
     "      <li>\n",
-    "        <strong>Transfer Funds:</strong>\n",
-    "        <p>Calculate a transfer amount from the Salary Account to the Savings Account using a given <code>savings_percentage</code>. Deduct this amount from the Salary Account and add it to the Savings Account.</p>\n",
+    "        <p>Create an instance of <code>SavingsAccount</code>, passing as parameters any <code>account_number</code> that you like and the <code>interest_rate</code> that is given in the solution function's parameters.</p>\n",
     "      </li>\n",
     "      <li>\n",
-    "        <strong>Project Future Balance:</strong>\n",
-    "        <p>Return the projected balance of the Savings Account after a specified number of years, provided by <code>years_passed</code>.</p>\n",
+    "        <p>Return a <strong>list</strong> containing the two instances you created.</p>\n",
     "      </li>\n",
     "    </ul>\n",
-    "\n",
-    "The solution function should return the balance of the Savings Account after the given number of years.\n",
-    "\n",
     "</div>"
    ]
   },
@@ -790,11 +784,21 @@
    "source": [
     "%%ipytest\n",
     "from abc import ABC, abstractmethod\n",
-    "from datetime import datetime\n",
     "\n",
-    "def solution_banking_system(tax_rate: float, interest_rate: float, gross_salary: int, savings_precentage: float, years_passed: int) -> float:\n",
-    "    # Write your solution here\n",
-    "    pass"
+    "def solution_banking_system(tax_rate: float, interest_rate: float) -> list:\n",
+    "    \"\"\"\n",
+    "    Defines abstract class `Account` with attributes `account_number` and `balance`, and methods `credit()`, `get_balance()`, and `debit()`.\n",
+    "    Implements `SalaryAccount` (with `tax_rate`) and `SavingsAccount` (with `interest_rate`) as derived classes, overriding `credit()` and `get_balance()`.\n",
+    "    Creates and returns instances of `SalaryAccount` and `SavingsAccount` in a list.\n",
+    "\n",
+    "    Args:\n",
+    "        tax_rate (float): Tax rate for SalaryAccount.\n",
+    "        interest_rate (float): Interest rate for SavingsAccount.\n",
+    "    Returns:\n",
+    "        list: Instances of SalaryAccount and SavingsAccount.\n",
+    "    \"\"\"\n",
+    "\n",
+    "    return"
    ]
   },
   {

tutorial/tests/test_13_object_oriented_programming_advanced.py

@@ -1,6 +1,5 @@
 import pathlib
 from abc import ABC, abstractmethod
-from datetime import datetime
 
 import pytest
 from numpy import average
@@ -91,9 +90,6 @@ def test_child_eye_color(mother_eye_color, father_eye_color, function_to_test):
 def reference_banking_system(
     tax_rate: float,
     interest_rate: float,
-    gross_salary: int,
-    savings_precentage: float,
-    years_passed: int,
 ) -> float:
     class Account(ABC):
         def __init__(self, account_number):
@@ -129,49 +125,103 @@ class SavingsAccount(Account):
         def __init__(self, account_number, interest_rate):
             super().__init__(account_number)
             self.interest_rate = interest_rate
-            self.creation_year = datetime.now().year
 
         def credit(self, amount):
             self.balance += amount
 
-        def get_balance(self, years_passed):
-            interest = self.balance * self.interest_rate * years_passed
-            return self.balance + interest
-
-    salary_account = SalaryAccount("SAL-001", tax_rate)
-    savings_account = SavingsAccount("SAV-001", interest_rate)
-
-    salary_account.credit(gross_salary)
+        def get_balance(self):
+            return self.balance + self.balance * self.interest_rate
 
-    amount_to_transfer = salary_account.get_balance() * savings_precentage
+    return [
+        SalaryAccount("SAL-001", tax_rate),
+        SavingsAccount("SAV-001", interest_rate),
+    ]
 
-    salary_account.debit(amount_to_transfer)
-    savings_account.credit(amount_to_transfer)
 
-    return savings_account.get_balance(years_passed)
+def validate_banking_system(solution_result):
+    assert isinstance(solution_result, list), "Solution must return a list."
+    assert len(solution_result) == 2, "The list must contain exactly two elements."
+    assert all(
+        isinstance(item, object) and type(item).__module__ != "builtins"
+        for item in solution_result
+    ), "Both elements in the list must be instances of custom classes."
+    assert all(
+        "Account" in [base.__name__ for base in type(item).__bases__]
+        for item in solution_result
+    ), "Both elements in the list must inherit from a class named 'Account'."
+    assert type(solution_result[0]).__name__ == "SalaryAccount", (
+        "The 1st class should be an instance of 'SalaryAccount'."
+    )
+    assert type(solution_result[1]).__name__ == "SavingsAccount", (
+        "The 2nd class should be an instance of 'SavingsAccount'."
+    )
+    # Check the class attributes: SalaryAccount
+    try:
+        attrs = list(vars(solution_result[0]))
+    except TypeError:
+        raise SubAssertionError from None
+    assert len(attrs) == 3, "The class 'SalaryAccount' should have 3 attributes."
+    assert "account_number" in attrs, (
+        "The class 'SalaryAccount' should have an attribute called 'account_number'."
+    )
+    assert "balance" in attrs, (
+        "The class 'SalaryAccount' should have an attribute called 'balance'."
+    )
+    assert "tax_rate" in attrs, (
+        "The class 'SalaryAccount' should have an attribute called 'tax_rate'."
+    )
+    # Check the class attributes: SavingsAccount
+    try:
+        attrs = list(vars(solution_result[1]))
+    except TypeError:
+        raise SubAssertionError from None
+    assert len(attrs) == 3, "The class 'SavingsAccount' should have 3 attributes."
+    assert "account_number" in attrs, (
+        "The class 'SavingsAccount' should have an attribute called 'account_number'."
+    )
+    assert "balance" in attrs, (
+        "The class 'SavingsAccount' should have an attribute called 'balance'."
+    )
+    assert "interest_rate" in attrs, (
+        "The class 'SavingsAccount' should have an attribute called 'interest_rate'."
+    )
+    # Check that each class has the required methods
+    required_methods = {"credit", "get_balance"}
+    for item in solution_result:
+        class_methods = {
+            method for method in dir(item) if callable(getattr(item, method))
+        }
+        assert required_methods.issubset(class_methods), (
+            f"The class '{type(item).__name__}' must have the methods: {', '.join(required_methods)}."
+        )
 
 
 @pytest.mark.parametrize(
-    "tax_rate, interest_rate, gross_salary, savings_precentage, years_passed",
+    "tax_rate, interest_rate",
     [
-        (0.20, 0.05, 10000, 0.3, 2),
-        (0.18, 0.04, 9300, 0.15, 3),
-        (0.13, 0.07, 8500, 0.18, 4),
+        (0.20, 0.05),
+        (0.18, 0.04),
     ],
 )
 def test_banking_system(
     tax_rate,
     interest_rate,
-    gross_salary,
-    savings_precentage,
-    years_passed,
     function_to_test,
 ):
-    assert function_to_test(
-        tax_rate, interest_rate, gross_salary, savings_precentage, years_passed
-    ) == reference_banking_system(
-        tax_rate, interest_rate, gross_salary, savings_precentage, years_passed
-    )
+    solution_result = function_to_test(tax_rate, interest_rate)
+    reference_result = reference_banking_system(tax_rate, interest_rate)
+
+    validate_banking_system(solution_result)
+
+    amount = 10000
+    # test SalaryAccount functions
+    solution_result[0].credit(amount)
+    reference_result[0].credit(amount)
+    assert solution_result[0].get_balance() == reference_result[0].get_balance()
+    # test SavingsAccount functions
+    solution_result[1].credit(amount)
+    reference_result[1].credit(amount)
+    assert solution_result[1].get_balance() == reference_result[1].get_balance()
 
 
 #
@@ -255,7 +305,7 @@ def test_store_inventory(function_to_test):
 
 
 #
-# Exercise 3: Music Streaming Service
+# Exercise 4: Music Streaming Service
 #