def METHOD_NAME(self, test_id, sagews):
    # warn about possible missing '*' with patterns like 3x^2 and 5(1+x)
    code = ("x=1\ny=3x^2x")
    m = conftest.message.execute_code(code=code, id=test_id)
    sagews.send_json(m)
    # expect 2 messages from worksheet client
    # 1 stderr
    typ, mesg = sagews.recv()
    assert typ == 'json'
    assert mesg['id'] == test_id
    assert 'stderr' in mesg
    assert 'implicit multiplication' in mesg['stderr']
    # 2 done
    conftest.recv_til_done(sagews, test_id)