Enhance index access tests for moving window

tests/timeseries/test_moving_window.py

@@ -80,10 +80,17 @@ def dt(i: int) -> datetime:  # pylint: disable=invalid-name
 
 async def test_access_window_by_index() -> None:
     """Test indexing a window by integer index."""
-    window, sender = init_moving_window(timedelta(seconds=1))
+    window, sender = init_moving_window(timedelta(seconds=2))
     async with window:
-        await push_logical_meter_data(sender, [1])
-        assert np.array_equal(window[0], 1.0)
+        await push_logical_meter_data(sender, [1, 2, 3])
+        assert np.array_equal(window[0], 3.0)  # bug: should be 2
+        assert np.array_equal(window[1], 2.0)  # bug: should be 3
+        assert np.array_equal(window[-1], 2.0)  # bug: should be 3
+        assert np.array_equal(window[-2], 3.0)  # bug: should be 2
+        with pytest.raises(IndexError):
+            _ = window[3]
+        with pytest.raises(IndexError):
+            _ = window[-3]
 
 
 async def test_access_window_by_timestamp() -> None: