message: [test]fix MockChainService.
diff: @@ -170,7 +170,7 @@ mod tests {
  let txpool = MockTxPoolService::new();
  let account_service = MockWalletService::new().unwrap();
  let state_service = MockChainStateService::new();
  - let chain_service = MockChainService::new();
  + let chain_service = MockChainService::default();
  let _rpc_actor = RpcActor::launch(
  config,
  txpool,
  