Will delete all data in schema. Only for test use!

def truncate_schema(self):
        """ Will delete all data in schema. Only for test use!"""

        assert self.server == 'localhost'
        con = self.connection or self._connect()
        self._initialize(con)
        cur = con.cursor()

        cur.execute('DELETE FROM publication;')
        cur.execute('TRUNCATE systems CASCADE;')

        con.commit()
        con.close()

        return