@Test
public void testException() {

    invocation.setMethodName("echo1");
    invocation.setParameterTypes(new Class<?>[]{String.class});
    invocation.setArguments(new Object[]{"arg2"});
    cacheFilter.invoke(invoker3, invocation);
    RpcResult rpcResult = (RpcResult) cacheFilter.invoke(invoker2, invocation);
    Assert.assertEquals(rpcResult.getValue(), "value2");
}