From fdc1af4551e4ac34564d36c6dea3c6b7520897c6 Mon Sep 17 00:00:00 2001
From: Tibyan Khalid <tibyankhalid410@gmail.com>
Date: Thu, 9 Jan 2025 20:13:16 +0200
Subject: [PATCH 1/2] Swap_letters challenge and tests

---
 solutions/Swap_letters.py            | 37 +++++++++++++++++++++++++++
 solutions/tests/test_Swap_letters.py | 38 ++++++++++++++++++++++++++++
 2 files changed, 75 insertions(+)
 create mode 100644 solutions/Swap_letters.py
 create mode 100644 solutions/tests/test_Swap_letters.py

diff --git a/solutions/Swap_letters.py b/solutions/Swap_letters.py
new file mode 100644
index 000000000..5800e6f16
--- /dev/null
+++ b/solutions/Swap_letters.py
@@ -0,0 +1,37 @@
+"""
+Created on 08/01/2024
+
+@author: Tibyan Khalid
+"""
+
+
+def Swap_letters(string: str) -> str:
+    """Swap_letters will return the string given with switched cases.
+
+    Parameters:
+      String(str) "the word that will get modified"
+
+    Returns: modified_string(str) "the string with swapped cases"
+
+    >>> Swap_letters("hello")
+    'HELLO'
+
+    >>> Swap_letters("HELLO")
+    'hello'
+
+    >>> Swap_letters("HeLlO")
+    'hElLo'
+    """
+    if not isinstance(string, str):
+        "Make sure the expected input is a string"
+        raise AssertionError("Input must be a string")
+
+    changed_string = ""
+    for char in string:
+        if char.islower():
+            changed_string = changed_string + char.upper()
+        elif char.isupper():
+            changed_string = changed_string + char.lower()
+        else:
+            changed_string = changed_string + char
+    return changed_string
diff --git a/solutions/tests/test_Swap_letters.py b/solutions/tests/test_Swap_letters.py
new file mode 100644
index 000000000..fec2f57be
--- /dev/null
+++ b/solutions/tests/test_Swap_letters.py
@@ -0,0 +1,38 @@
+"""
+Created on 08/01/2024
+
+@author: Tibyan Khalid
+"""
+
+import unittest
+
+from ..Swap_letters import Swap_letters
+
+
+class TestSwapletters(unittest.TestCase):
+    """Unittests for the Swap_letters function"""
+
+    def test_lowercase_all(self):
+        "Testing from lowercase to uppercase"
+        self.assertEqual(Swap_letters("tibyan"), "TIBYAN")
+
+    def test_uppercase_all(self):
+        "Testing from uppercase to lowercase"
+        self.assertEqual(Swap_letters("TIBYAN"), "tibyan")
+
+    def test_mixed_cases(self):
+        "Testing mixed spaces"
+        self.assertEqual(Swap_letters("TiByAn"), "tIbYaN")
+
+    def test_non_string_entry(self):
+        "Raise an error if entry is not a string"
+        with self.assertRaises(AssertionError):
+            Swap_letters(57)
+
+    def test_spaces(self):
+        "Handle spaces correctly"
+        self.assertEqual(Swap_letters("Hello World"), "hELLO wORLD")
+
+
+if __name__ == "__main__":
+    unittest.main()

From c3d22d01c9cda80abcdf82ed04f4e7c694ab008a Mon Sep 17 00:00:00 2001
From: Tibyan Khalid <tibyankhalid410@gmail.com>
Date: Sun, 12 Jan 2025 09:29:10 +0200
Subject: [PATCH 2/2] Added changes as per request of the reveiwer such as
 including edge cases tests and more descriptive docstrings

---
 solutions/Swap_letters.py            |  8 +++++---
 solutions/tests/test_Swap_letters.py | 15 +++++++++++++--
 2 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/solutions/Swap_letters.py b/solutions/Swap_letters.py
index 5800e6f16..05a21bf18 100644
--- a/solutions/Swap_letters.py
+++ b/solutions/Swap_letters.py
@@ -2,6 +2,8 @@
 Created on 08/01/2024
 
 @author: Tibyan Khalid
+
+This file contains the function Swap_letters that swaps the case of each letter in a string.
 """
 
 
@@ -29,9 +31,9 @@ def Swap_letters(string: str) -> str:
     changed_string = ""
     for char in string:
         if char.islower():
-            changed_string = changed_string + char.upper()
+            changed_string += char.upper()
         elif char.isupper():
-            changed_string = changed_string + char.lower()
+            changed_string += char.lower()
         else:
-            changed_string = changed_string + char
+            changed_string += char
     return changed_string
diff --git a/solutions/tests/test_Swap_letters.py b/solutions/tests/test_Swap_letters.py
index fec2f57be..f4cb40d90 100644
--- a/solutions/tests/test_Swap_letters.py
+++ b/solutions/tests/test_Swap_letters.py
@@ -2,6 +2,8 @@
 Created on 08/01/2024
 
 @author: Tibyan Khalid
+
+This file contains boundary cases and defensive assertion tests for the function Swap_letters.
 """
 
 import unittest
@@ -9,8 +11,9 @@
 from ..Swap_letters import Swap_letters
 
 
-class TestSwapletters(unittest.TestCase):
-    """Unittests for the Swap_letters function"""
+class TestSwapLettersFunctionality(unittest.TestCase):
+    """Test cases for validating the behavior of the Swap_letters function,
+    including edge cases and defensive assertions."""
 
     def test_lowercase_all(self):
         "Testing from lowercase to uppercase"
@@ -33,6 +36,14 @@ def test_spaces(self):
         "Handle spaces correctly"
         self.assertEqual(Swap_letters("Hello World"), "hELLO wORLD")
 
+    def test_empty_string(self):
+        "Test for an empty string input"
+        self.assertEqual(Swap_letters(""), "")
+
+    def test_special_characters(self):
+        "Test for special characters input"
+        self.assertEqual(Swap_letters("1234!@#$"), "1234!@#$")
+
 
 if __name__ == "__main__":
     unittest.main()