Do not force copy on Nones in ring buffer window

The functionality was not working as intended. Moreover the decision
whether to enforce a copy or not should be left to the user even if the
data contains None values.

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

Author: cwasicki

src/frequenz/sdk/timeseries/_ringbuffer/buffer.py

@@ -219,7 +219,6 @@ def window(
 
         Will return a copy in the following cases:
         * The requested time period is crossing the start/end of the buffer.
-        * The requested time period contains missing entries.
         * The force_copy parameter was set to True (default False).
 
         The first case can be avoided by using the appropriate
@@ -261,10 +260,7 @@ def window(
                 assert False, f"Unknown _buffer type: {type(self._buffer)}"
             return self._buffer[start_index:]
 
-        # Return a copy if there are none-values in the data
-        if force_copy or any(
-            map(lambda gap: gap.contains(start) or gap.contains(end), self._gaps)
-        ):
+        if force_copy:
             return deepcopy(self[start_index:end_index])
 
         return self[start_index:end_index]

tests/timeseries/test_ringbuffer.py

@@ -449,6 +449,6 @@ def test_window() -> None:
     assert [0, np.nan, 2] == list(win)
     buffer._buffer[1] = 1  # pylint: disable=protected-access
     # Test whether the window is a view or a copy
-    assert [0, 1, 2] == list(win)  # NB: second element should be NaN according to docs
+    assert [0, 1, 2] == list(win)
     win = buffer.window(dt(0), dt(3), force_copy=False)
     assert [0, 1, 2] == list(win)