Implement Manual String Reversal Function

.gitignore

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+__pycache__/
+*.pyc
+*.pyo
+*.pyd
+.pytest_cache/
+.venv/
+venv/
+dist/
+build/
+*.egg-info/
+.env
+.DS_Store

src/string_utils.py

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+def reverse_string(input_string: str) -> str:
+    """
+    Reverse the given input string manually, without using slice notation or reverse().
+
+    Args:
+        input_string (str): The string to be reversed.
+
+    Returns:
+        str: The reversed string.
+
+    Raises:
+        TypeError: If the input is not a string.
+    """
+    # Check if input is a string
+    if not isinstance(input_string, str):
+        raise TypeError("Input must be a string")
+
+    # Convert string to list of characters
+    chars = list(input_string)
+
+    # Manually reverse the list of characters
+    left, right = 0, len(chars) - 1
+    while left < right:
+        # Swap characters
+        chars[left], chars[right] = chars[right], chars[left]
+
+        # Move towards the center
+        left += 1
+        right -= 1
+
+    # Convert back to string and return
+    return ''.join(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_single_char():
+    """Test reversal of a single character string."""
+    assert reverse_string("a") == "a"
+
+def test_reverse_string_with_spaces():
+    """Test reversal of string with spaces."""
+    assert reverse_string("hello world") == "dlrow olleh"
+
+def test_reverse_string_with_special_chars():
+    """Test reversal of string with special characters."""
+    assert reverse_string("a1b2c3!@#") == "#@!3c2b1a"
+
+def test_reverse_string_unicode():
+    """Test reversal of string with unicode characters."""
+    assert reverse_string("こんにちは") == "はちにんこ"
+
+def test_reverse_string_invalid_input():
+    """Test that TypeError is raised 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(["hello"])