Unified String Reversal: Enhanced Type Safety and Cross-Module Consistency

src/string_reversal.py

@@ -1,4 +1,4 @@
-def reverse_string(input_string):
+def reverse_string(input_string: str) -> str:
     """
     Reverse the given input string manually, without using slice notation or reverse().
 
@@ -15,6 +15,10 @@ def reverse_string(input_string):
     if not isinstance(input_string, str):
         raise TypeError("Input must be a string")
 
+    # Handle empty string case
+    if not input_string:
+        return ""
+
     # Convert string to list of characters
     chars = list(input_string)
 

src/string_utils.py

@@ -1,4 +1,4 @@
-def reverse_string(input_string):
+def reverse_string(input_string: str) -> str:
     """
     Reverse the given string using a manual character-by-character approach.
 
@@ -15,6 +15,10 @@ def reverse_string(input_string):
     if not isinstance(input_string, str):
         raise TypeError("Input must be a string")
 
+    # Handle empty string case
+    if not input_string:
+        return ""
+
     # Use list to manually reverse the string
     reversed_chars = []
     for i in range(len(input_string) - 1, -1, -1):

tests/test_string_reversal.py

@@ -4,11 +4,16 @@
 def test_reverse_standard_string():
     """Test reversing a standard string."""
     assert reverse_string("hello") == "olleh"
+    assert reverse_string("python") == "nohtyp"
 
 def test_reverse_empty_string():
     """Test reversing an empty string."""
     assert reverse_string("") == ""
 
+def test_reverse_single_char_string():
+    """Test reversing a single character string."""
+    assert reverse_string("a") == "a"
+
 def test_reverse_palindrome():
     """Test reversing a palindrome string."""
     assert reverse_string("racecar") == "racecar"