    def test_small(self):
        """
        inputs:

        num1: scalar       ----------1------------>
        num2: queue        ----1----2----3---4----->
        timestamp: queue   --1000-2000-3000-4000--->

        params:
            time_range_sec: 3
            time_step_sec: 2

        time_window: [0s, 3s)  [2s, 5s) [4s, 6s)

        outputs:

        que1:
        num1: scalar   -----1----->
        num2: queue    --1-2-3-4--->
        sum1: queue    --2-3-1----->
        sum2: queue    --3-9-4----->

        que2:
        num1: scalar   ------1------>
        sum1: queue    --2-3-1----->
        sum2: queue    --3-9-4----->
        """

        info = copy.deepcopy(self.node_info)
        info['iter_info']['param']['time_step_sec'] = 2
        exp_ret1 = [
            {'num1': 1, 'num2': 1, 'sum1': 2, 'sum2': 3},
            {'num1': 1, 'num2': 2, 'sum1': 3, 'sum2': 9},
            {'num1': 1, 'num2': 3, 'sum1': 1, 'sum2': 4},
            {'num1': 1, 'num2': 4, 'sum1': Empty(), 'sum2': Empty()}
        ]

        exp_ret2 = [
            {'num1': 1, 'sum1': 2, 'sum2': 3},
            {'num1': 1, 'sum1': 3, 'sum2': 9},
            {'num1': 1, 'sum1': 1, 'sum2': 4}
        ]
        self._test_function(info, exp_ret1, exp_ret2)
inputs:

num1: scalar       ----------1------------>
num2: queue        ----1----2----3---4----->
timestamp: queue   --1000-2000-3000-4000--->

params:
time_range_sec: 3
time_step_sec: 2

time_window: [0s, 3s)  [2s, 5s) [4s, 6s)

outputs:

que1:
num1: scalar   -----1----->
num2: queue    --1-2-3-4--->
sum1: queue    --2-3-1----->
sum2: queue    --3-9-4----->

que2:
num1: scalar   ------1------>
sum1: queue    --2-3-1----->
sum2: queue    --3-9-4----->
tests/unittests/runtime/test_time_window_node.py