protected abstract String getGroupId(T request);
@Test
    public void testManyNodes() {
        Node node1 = Mockito.mock(Node.class);
        Mockito.when(node1.getGroupId()).thenReturn("test");
        Mockito.when(node1.getNodeId()).thenReturn(new NodeId("test", new PeerId("localhost", 8081)));
        NodeOptions opts = new NodeOptions();
        Mockito.when(node1.getOptions()).thenReturn(opts);
        NodeManager.getInstance().addAddress(new Endpoint("localhost", 8081));
        NodeManager.getInstance().add(node1);

        Node node2 = Mockito.mock(Node.class);
        Mockito.when(node2.getGroupId()).thenReturn("test");
        Mockito.when(node2.getNodeId()).thenReturn(new NodeId("test", new PeerId("localhost", 8082)));
        Mockito.when(node2.getOptions()).thenReturn(opts);
        NodeManager.getInstance().addAddress(new Endpoint("localhost", 8082));
        NodeManager.getInstance().add(node2);

        this.processor = new MockCliRequestProcessor(null, "test");
        this.processor.handleRequest(asyncContext, TestUtils.createPingRequest());
        ErrorResponse resp = (ErrorResponse) asyncContext.getResponseObject();
        assertNotNull(resp);
        assertEquals(RaftError.EINVAL.getNumber(), resp.getErrorCode());
        assertEquals("Peer must be specified since there're 2 nodes in group test", resp.getErrorMsg());
    }