code: @Test() public void testNoInvoke(){
    dic=mock(Directory.class);
    given(dic.getUrl()).willReturn(url);
    given(dic.list(invocation)).willReturn(null);
    given(dic.getInterface()).willReturn(FailoverClusterInvokerTest.class);
    invocation.setMethodName("method1");
    invokers.add(invoker1);
    FailoverClusterInvoker<FailoverClusterInvokerTest> invoker=new FailoverClusterInvoker<FailoverClusterInvokerTest>(dic);
    try {
      invoker.invoke(invocation);
      fail();
    }
   catch (  RpcException expected) {
      assertFalse(expected.getCause() instanceof RpcException);
    }
  }
  