    def test_count_window(self):
        """
        size == step

        Inputs:

          ----1-2-3-4-5-6-7-8-9--->

        size: 2
        step: 2

        outputs:
          ----[1, 2] - [3, 4] - [5, 6] - [7, 8] - [9] ---->
        """
        ret = [[1, 2], [3, 4], [5, 6], [7, 8], [9]]
        index = 0
        buf = _WindowBuffer(2, 2)
        for i in range(1, 10):
            if buf(i, i - 1):
                self.assertEqual(buf.data, ret[index])
                index += 1
                buf = buf.next()

        while buf is not None:
            if buf.data:
                self.assertEqual(buf.data, ret[index])
                index += 1
            buf = buf.next()
size == step

Inputs:

----1-2-3-4-5-6-7-8-9--->

size: 2
step: 2

outputs:
----[1, 2] - [3, 4] - [5, 6] - [7, 8] - [9] ---->
tests/unittests/runtime/test_window_node.py