@classmethod
def get_slowest_tests(cls, num=10):
    """Returns the slow num tests.
        
        :param num: The maximum number of results to be returned.
        :type num: int
        
        """
    cur = cls.get_cursor()
    q = (
        'SELECT file, module, class, func, AVG(elapsed) as elapsed FROM {} GROUP BY module, class, func ORDER BY elapsed DESC LIMIT {}'
        )
    cur.execute(q.format(cls.meta['table'], num))
    return cur.fetchall()
