Enhanced String Manipulation: Robust Utility Implementation with Comprehensive Testing

requirements.txt

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+pytest

src/string_utils.py

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+def reverse_string(input_string):
+    """
+    Reverse a given string using a manual character-by-character approach.
+
+    Args:
+        input_string (str): The string to be reversed.
+
+    Returns:
+        str: The reversed string.
+
+    Raises:
+        TypeError: If the input is not a string.
+    """
+    # Validate input is a string
+    if not isinstance(input_string, str):
+        raise TypeError("Input must be a string")
+
+    # Use a list to build the reversed string
+    reversed_chars = []
+
+    # Iterate through the string from end to beginning
+    for i in range(len(input_string) - 1, -1, -1):
+        reversed_chars.append(input_string[i])
+
+    # Convert list of characters back to string
+    return ''.join(reversed_chars)

tests/test_string_utils.py

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+import pytest
+from src.string_utils import reverse_string
+
+def test_reverse_string_basic():
+    """Test basic string reversal."""
+    assert reverse_string("hello") == "olleh"
+    assert reverse_string("python") == "nohtyp"
+
+def test_reverse_string_empty():
+    """Test reversal of an empty string."""
+    assert reverse_string("") == ""
+
+def test_reverse_string_special_chars():
+    """Test reversal with special characters and spaces."""
+    assert reverse_string("Hello, World!") == "!dlroW ,olleH"
+    assert reverse_string("  trim  ") == "  mirt  "
+
+def test_reverse_string_unicode():
+    """Test reversal with Unicode characters."""
+    assert reverse_string("こんにちは") == "はちにんこ"
+    assert reverse_string("🌈🦄") == "🦄🌈"
+
+def test_reverse_string_invalid_input():
+    """Test error handling for non-string inputs."""
+    with pytest.raises(TypeError, match="Input must be a string"):
+        reverse_string(123)
+
+    with pytest.raises(TypeError, match="Input must be a string"):
+        reverse_string(None)
+
+    with pytest.raises(TypeError, match="Input must be a string"):
+        reverse_string(["list"])