Drop empty Matryoshka buckets

tests/actor/_power_managing/test_matryoshka.py

@@ -4,8 +4,10 @@
 """Tests for the Matryoshka power manager algorithm."""
 
 import asyncio
+import re
 from datetime import datetime, timedelta, timezone
 
+import pytest
 from frequenz.quantities import Power
 
 from frequenz.sdk import timeseries
@@ -36,13 +38,14 @@ def tgt_power(  # pylint: disable=too-many-arguments,too-many-positional-argumen
         expected: float | None,
         creation_time: float | None = None,
         must_send: bool = False,
+        batteries: frozenset[int] | None = None,
     ) -> None:
         """Test the target power calculation."""
         self._call_count += 1
         tgt_power = self.algorithm.calculate_target_power(
-            self._batteries,
+            self._batteries if batteries is None else batteries,
             Proposal(
-                component_ids=self._batteries,
+                component_ids=self._batteries if batteries is None else batteries,
                 source_id=f"actor-{priority}",
                 preferred_power=None if power is None else Power.from_watts(power),
                 bounds=timeseries.Bounds(
@@ -368,6 +371,7 @@ async def test_matryoshka_drop_old_proposals() -> None:
     With inclusion bounds, and exclusion bounds -30.0 to 30.0.
     """
     batteries = frozenset({2, 5})
+    overlapping_batteries = frozenset({5, 8})
 
     system_bounds = _base_types.SystemBounds(
         timestamp=datetime.now(tz=timezone.utc),
@@ -424,3 +428,58 @@ async def test_matryoshka_drop_old_proposals() -> None:
     tester.tgt_power(
         priority=1, power=20.0, bounds=(20.0, 50.0), expected=25.0, must_send=True
     )
+
+    # When all proposals are too old, they are dropped, and the buckets are dropped as
+    # well.  After that, sending a request for a different but overlapping bucket will
+    # succeed.  And it will fail until then.
+    with pytest.raises(
+        NotImplementedError,
+        match=re.escape(
+            "PowerManagingActor: component IDs frozenset({8, 5}) are already "
+            + "part of another bucket.  Overlapping buckets are not yet supported."
+        ),
+    ):
+        tester.tgt_power(
+            priority=1,
+            power=25.0,
+            bounds=(25.0, 50.0),
+            expected=25.0,
+            must_send=True,
+            batteries=overlapping_batteries,
+        )
+
+    tester.tgt_power(
+        priority=1,
+        power=25.0,
+        bounds=(25.0, 50.0),
+        creation_time=now - 70.0,
+        expected=25.0,
+        must_send=True,
+    )
+    tester.tgt_power(
+        priority=2,
+        power=25.0,
+        bounds=(25.0, 50.0),
+        creation_time=now - 70.0,
+        expected=25.0,
+        must_send=True,
+    )
+    tester.tgt_power(
+        priority=3,
+        power=25.0,
+        bounds=(25.0, 50.0),
+        creation_time=now - 70.0,
+        expected=25.0,
+        must_send=True,
+    )
+
+    tester.algorithm.drop_old_proposals(now)
+
+    tester.tgt_power(
+        priority=1,
+        power=25.0,
+        bounds=(25.0, 50.0),
+        expected=25.0,
+        must_send=True,
+        batteries=overlapping_batteries,
+    )