def rotateString(s: str, k: int) -> str:
    """Rotate a string by k positions."""
    k %= len(s)
    return s[k:] + s[:k]


print("Testing rotateString()...", end="")
assert rotateString("abcd", 1) == "bcda"
assert rotateString("abcd", -1) == "dabc"
assert rotateString("efgh", 4) == "efgh"
assert rotateString("coffee", 2) == "ffeeco"
assert rotateString("112cmu", -3) == "cmu112"
assert rotateString("water", -9) == "aterw"
print("Passed!")