solution.py

SUBMIT = True
#ya venia con la respuesta xd

def case_inverter(s: str) -> str:  # noqa: ARG001
    """
    Inverts the case of each character in a string.
    """
    inverted_s = ""
    for char in s:
        if char.islower():
            inverted_s += char.upper()
        elif char.isupper():
            inverted_s += char.lower()
        else:
            inverted_s += char
    return inverted_s


def test() -> None:
    """Simple self-test for Case Inverter."""
    cases = [
        ("Hello World!", "hELLO wORLD!"),
        ("", ""),
        ("all lower", "ALL UPPER"),
        ("ALL UPPER", "all lower"),
        ("1234567890 !@#$%^&*()", "1234567890 !@#$%^&*()"),
        ("Python 3.12", "pYTHON 3.12"),
    ]
    for text, expected in cases:
        try:
            res = case_inverter(text)
            assert res == expected, (
                f"Failed for text='{text}': expected {expected}, got {res}"
            )
        except AssertionError as e:
            print(f"❌ {e}")
            return
    print("✅ All tests passed!")


if __name__ == "__main__":
    test()