Solution for Sponge Case Challenge

solutions/challenge_2/README.md

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+# Challenge: SpongeCase
+
+## Description
+
+SpongeCase is a style of text where letters alternately appear
+in lower and upper case.
+For example, the word in spongeCase would be `sPoNgEcAsE`.
+
+Write a function that converts the given string into spongeCase.
+
+## Example
+
+```python
+spongecase("hello world")
+# Output: "hElLo wOrLd"
+
+spongecase("Python")
+# Output: "pYtHoN"
+
+- Challenge Link: [GitHub Issue](https://github.com/MIT-Emerging-Talent/ET6-foundations-group-04/issues/2)

solutions/challenge_2/spongecase.py

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+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+"""
+A module for converting strings into SpongeCase (alternating lower and upper case).
+
+Module contents:
+    - spongecase: Converts a string into SpongeCase
+
+Created on 28/12/2024
+Author: Chrismy Leprince Paul Augustin
+"""
+
+
+def spongecase(text: str) -> str:
+    """Converts a string into SpongeCase, where letters alternate between lower
+    and upper case, starting with lower case.
+
+    Parameters:
+        text: str, a string to be converted into SpongeCase
+
+    Returns -> str: The SpongeCase version of the input string
+
+    Examples:
+        >>> spongecase("hello world")
+        'hElLo wOrLd'
+        >>> spongecase("PYTHON")
+        'pYtHoN'
+        >>> spongecase("HELLO!")
+        'hElLo!'
+    """
+    result_chars = []
+    for index, char in enumerate(text):
+        if index % 2 == 0:
+            # Even index -> lowercase
+            result_chars.append(char.lower())
+        else:
+            # Odd index -> uppercase
+            result_chars.append(char.upper())
+    return "".join(result_chars)

solutions/tests/challenge_2/test_spongecase.py

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+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+"""
+Test module for spongecase function.
+
+Test categories:
+    - Basic cases: typical strings, single words
+    - Edge cases: empty string, all uppercase, all lowercase
+    - Special characters: punctuation, digits, symbols
+
+Created on 2024-12-28
+Author: Chrismy Leprince Paul Augustin
+"""
+
+import unittest
+
+from solutions.challenge_2.spongecase import spongecase
+
+
+class TestSpongeCase(unittest.TestCase):
+    """Test suite for the spongecase function."""
+
+    def test_spongecase_basic(self):
+        """
+        It should convert a typical string containing spaces into SpongeCase.
+
+        Example:
+            "hello world" -> "hElLo wOrLd"
+        """
+        self.assertEqual(spongecase("hello world"), "hElLo wOrLd")
+
+    def test_spongecase_single_word(self):
+        """
+        It should convert a single word into SpongeCase.
+
+        Example:
+            "Python" -> "pYtHoN"
+        """
+        self.assertEqual(spongecase("Python"), "pYtHoN")
+
+    def test_spongecase_empty_string(self):
+        """
+        It should handle an empty string by returning an empty string.
+
+        Example:
+            "" -> ""
+        """
+        self.assertEqual(spongecase(""), "")
+
+    def test_spongecase_all_caps(self):
+        """
+        It should convert an all-caps string into SpongeCase.
+
+        Example:
+            "HELLO" -> "hElLo"
+        """
+        self.assertEqual(spongecase("HELLO"), "hElLo")
+
+    def test_spongecase_all_lowercase(self):
+        """
+        It should convert an all-lowercase string into SpongeCase.
+
+        Example:
+            "world" -> "wOrLd"
+        """
+        self.assertEqual(spongecase("world"), "wOrLd")
+
+    def test_spongecase_special_characters(self):
+        """
+        It should alternate case while preserving special characters
+        and digits in place.
+
+        Mapping indices:
+            Index:  0 1 2 3 4  5 6   7   8  9
+            Char:   H e l l o  ? 1   #   A  b
+            Case:   h E l L o  ? 1   #   a  B
+            Result: "hElLo?1#aB"
+        """
+        self.assertEqual(spongecase("Hello?1#Ab"), "hElLo?1#aB")