Use window method in moving window's getitem magic

The `__getitem__` method in moving window was not working properly. Since its
functionality is already provided by the window method it one can be
called from the getitem magic.

Signed-off-by: cwasicki <[email protected]>

Author: cwasicki

src/frequenz/sdk/timeseries/_moving_window.py

@@ -367,30 +367,18 @@ def __getitem__(self, key: SupportsIndex | datetime | slice) -> float | ArrayLik
             A float if the key is a number or a timestamp.
             an numpy array if the key is a slice.
         """
+        if isinstance(key, slice):
+            if not (key.step is None or key.step == 1):
+                raise ValueError("Slicing with a step other than 1 is not supported.")
+            return self.window(key.start, key.stop)
+
         if self._buffer.count_valid() == 0:
             raise IndexError("The buffer is empty.")
-        if isinstance(key, slice):
-            if isinstance(key.start, int) or isinstance(key.stop, int):
-                if key.start is None or key.stop is None:
-                    key = slice(slice(key.start, key.stop).indices(self.count_valid()))
-            elif isinstance(key.start, datetime) or isinstance(key.stop, datetime):
-                if key.start is None:
-                    key = slice(self._buffer.time_bound_oldest, key.stop)
-                if key.stop is None:
-                    key = slice(key.start, self._buffer.time_bound_newest)
-
-            _logger.debug("Returning slice for [%s:%s].", key.start, key.stop)
-
-            # we are doing runtime typechecks since there is no abstract slice type yet
-            # see also (https://peps.python.org/pep-0696)
-            if isinstance(key.start, datetime) and isinstance(key.stop, datetime):
-                return self._buffer.window(key.start, key.stop)
-            if isinstance(key.start, int) and isinstance(key.stop, int):
-                return self._buffer[key]
-        elif isinstance(key, datetime):
+
+        if isinstance(key, datetime):
             _logger.debug("Returning value at time %s ", key)
             return self._buffer[self._buffer.to_internal_index(key)]
-        elif isinstance(key, SupportsIndex):
+        if isinstance(key, SupportsIndex):
             _logger.debug("Returning value at index %s ", key)
             return self._buffer[key]
 

tests/timeseries/test_moving_window.py

@@ -111,12 +111,21 @@ async def test_access_window_by_int_slice() -> None:
         assert np.array_equal(window[5:14], np.array(data[5:14]))
         assert np.array_equal(window.window(5, 14), np.array(data[5:14]))
 
+        # Test with step size (other than 1 not supported)
+        assert np.array_equal(window[5:14:1], np.array(data[5:14]))
+        assert np.array_equal(window[5:14:None], np.array(data[5:14]))
+        with pytest.raises(ValueError):
+            _ = window[5:14:2]
+        with pytest.raises(ValueError):
+            _ = window[14:5:-1]
+
     window, sender = init_moving_window(timedelta(seconds=5))
 
     def test_eq(expected: list[float], start: int | None, end: int | None) -> None:
         assert np.allclose(
             window.window(start, end), np.array(expected), equal_nan=True
         )
+        assert np.allclose(window[start:end], np.array(expected), equal_nan=True)
 
     async with window:
         test_eq([], 0, 1)