def make_mock_video_ids(num_videos):
    """Makes a list of video ids used for unit tests.

    num_videos: an integer; the number of mock video ids to make. 

    Returns: a list of strings of that can be used as video ids for unit tests.
    """
    video_ids = []

    for video_num in range(num_videos):
        video_ids.append(f"video{video_num}")

    return video_ids