def METHOD_NAME(rand, index_path, file_names):
    file_name_to_corrupt = rand.choice(file_names)
    full_path = os.path.join(index_path, file_name_to_corrupt)
    size_in_bytes = os.path.getsize(full_path)
    if size_in_bytes == 0:
        raise RuntimeError(f'oh no, file {full_path} is 0 bytes long, which should never happen in a healthy Lucene index!')
    return file_name_to_corrupt, full_path, size_in_bytes