Utility Functions

requirements.txt

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+pytest

src/string_reversal.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")
+
+    # Handle empty string case
+    if not input_string:
+        return ""
+
+    # 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 from both ends
+        chars[left], chars[right] = chars[right], chars[left]
+        left += 1
+        right -= 1
+
+    # Convert list back to string and return
+    return ''.join(chars)

src/string_utils.py

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+def reverse_string(input_string: str) -> str:
+    """
+    Reverse the 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.
+    """
+    # Type checking
+    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):
+        reversed_chars.append(input_string[i])
+
+    # Convert list back to string
+    return ''.join(reversed_chars)

tests/test_string_reversal.py

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+import pytest
+from src.string_reversal import reverse_string
+
+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"
+
+def test_reverse_with_spaces():
+    """Test reversing a string with spaces."""
+    assert reverse_string("hello world") == "dlrow olleh"
+
+def test_reverse_with_special_characters():
+    """Test reversing a string with special characters."""
+    assert reverse_string("a1b2c3!@#") == "#@!3c2b1a"
+
+def test_reverse_unicode_string():
+    """Test reversing a string with Unicode characters."""
+    assert reverse_string("こんにちは") == "はちにんこ"
+
+def test_invalid_input_type():
+    """Test that a TypeError is raised for non-string inputs."""
+    with pytest.raises(TypeError, match="Input must be a string"):
+        reverse_string(12345)
+
+    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"])

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_with_spaces():
+    """Test reversal of strings with spaces."""
+    assert reverse_string("hello world") == "dlrow olleh"
+
+def test_reverse_string_special_chars():
+    """Test reversal of strings with special characters."""
+    assert reverse_string("a!b@c#") == "#c@b!a"
+
+def test_reverse_string_unicode():
+    """Test reversal of unicode strings."""
+    assert reverse_string("こんにちは") == "はちにんこ"
+
+def test_reverse_string_mixed_chars():
+    """Test reversal of strings with mixed character types."""
+    assert reverse_string("Hello, World! 123") == "321 !dlroW ,olleH"
+
+def test_reverse_string_invalid_input():
+    """Test that a 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"])