TFE_Execute(op.get(), &result_handles, &num_retvals, status.get());
    ASSERT_TRUE(TF_GetCode(status.get()) == TF_INVALID_ARGUMENT)
        << TF_Message(status.get());
  }
}

TensorHandlePtr CollectiveSum(TFE_Context* context, TFE_TensorHandle* input,
                              int group_size, TF_Status* status) {
  std::unique_ptr<TFE_Op, decltype(&TFE_DeleteOp)> op(