code: @Test public void testBindingAttachment(){
    final String attachKey="attach";
    final String attachValue="value";
    RpcContext.getContext().setAttachment(attachKey,attachValue);
    Map<String,String> attachments=RpcContext.getContext().getAttachments();
    Assert.assertTrue("set attachment failed!",attachments != null && attachments.size() == 1);
    cluster=new AbstractClusterInvoker(dic){
      @Override protected Result doInvoke(    Invocation invocation,    List invokers,    LoadBalance loadbalance) throws RpcException {
        String value=invocation.getAttachment(attachKey);
        Assert.assertTrue("binding attachment failed!",value != null && value.equals(attachValue));
        return null;
      }
    }
  ;
    cluster.invoke(invocation);
  }
  