Merge pull request #152 from MIT-Emerging-Talent/count-character

add solution to Count Character challenge and updated README

solutions/README.md

@@ -44,6 +44,7 @@ while corresponding test files are maintained in the `tests` folder.
 | `check_prime_number.py` | Given a positive int if it is a prime number| Özgür |
 | `password_strength.py` | Checks the strength of a password| Anas |
 | `decimal_to_binary.py` | Converts decimal to its equivalent binary| Anas |
+| `count_character.py`| counts occurrences of a character in a string| Mohamed|
 | `is_positive.py` | Determines if a given number is positive | Faisal |
 | `is_palindrome.py` | Checks string palindrome properties | Faisal |
 

solutions/count_character.py

@@ -0,0 +1,49 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+"""
+A module for counting occurrences of a character in a string.
+
+Created on 12/1/2025
+@author: Mohamed Altayeb
+Group: ET foundations group 16 (Matrix)
+
+Module functions:
+    - count_character: counts occurrences of a character in a string.
+
+"""
+
+
+def count_character(input_string: str, character: str) -> int:
+    """
+    Counts the number of occurrences of a specific character in a string
+    It will treat capital letters as different characters compared to small letters.
+
+    Arguments:
+      input_string (str): The string to count in.
+      character (str): The character to count.
+
+    Returns:
+      int: The number of occurrences of the character in the string.
+
+    Raises:
+    AssertionError: if input string is not a string or character is not a single
+      character string.
+
+    >>> count_character("Mohamed", "m")
+    1
+
+    >>> count_character("test", "l")
+    0
+
+    >>> count_character("mississippi", "s")
+    4
+
+    """
+    # Make sure inputs are correct
+    if not isinstance(input_string, str):
+        raise AssertionError("The input_string must be a string.")
+    if not isinstance(character, str) or len(character) != 1:
+        raise AssertionError("The character must be a single character string.")
+
+    # Return the number of occurrences of character in the string
+    return input_string.count(character)

solutions/tests/test_count_character.py

@@ -0,0 +1,56 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+"""
+Test module for count_character function
+
+Created on 11/1/2025
+@author: Mohamed Altayeb
+Group: ET foundations group 16 (Matrix)
+"""
+
+import unittest
+
+from ..count_character import count_character
+
+
+class TestCountCharacter(unittest.TestCase):
+    """Test suite for the count_character function"""
+
+    def test_string_with_no_occurrence(self):
+        """it should return zero when the character is not in the string"""
+        self.assertEqual(count_character("abcdefg", "h"), 0)
+
+    def test_empty_string(self):
+        """it should return zero when the input string is empty"""
+        self.assertEqual(count_character("", "h"), 0)
+
+    def test_string_with_normal_occurrence(self):
+        """it should return the number of occurrences when the character in the string"""
+        self.assertEqual(count_character("looking for a char", "o"), 3)
+
+    def test_string_with_capital_and_small_letters(self):
+        """it should treat capital letters as different characters compared to their small
+        counterparts"""
+        self.assertEqual(count_character("Mohammed Made soMething", "M"), 3)
+
+    def test_counting_spaces(self):
+        """it should count the number of spaces in a string when passed a space as
+        a character"""
+        self.assertEqual(
+            count_character("there are a  l ot of spaces i n  this l ine", " "), 13
+        )
+
+    def test_input1_is_not_a_string(self):
+        """It should raise AssertionError if first input is not a string"""
+        with self.assertRaises(AssertionError):
+            count_character(["mohamed"], "m")
+
+    def test_character_is_not_a_string(self):
+        """It should raise AssertionError if first input is not a single character string"""
+        with self.assertRaises(AssertionError):
+            count_character(["mohamed"], 2)
+
+    def test_length_of_character_is_not_one(self):
+        """It should raise AssertionError if length of character is not one"""
+        with self.assertRaises(AssertionError):
+            count_character(["mohamed"], "med")