Stop Select in BatteriesStatus and BatteriesStatusTracker

Select that is not closed causes errors in unit tests.

Signed-off-by: ela-kotulska-frequenz <elzbieta.kotulska@frequenz.com>

src/frequenz/sdk/actor/power_distributing/_batteries_status.py

@@ -131,7 +131,11 @@ def __init__(
                 channel_name=channel.name, tracker=tracker
             )
 
-        self._task = asyncio.create_task(self._run(receivers))
+        self._select: Select = Select(
+            **receivers,
+        )
+
+        self._task = asyncio.create_task(self._run())
 
     async def stop(self) -> None:
         """Stop tracking batteries status."""
@@ -141,21 +145,14 @@ async def stop(self) -> None:
                 for battery in self._batteries.values()
             ]
         )
+        await self._select.stop()
         await cancel_and_await(self._task)
 
-    async def _run(self, receivers: Dict[str, Receiver[BatteryStatus]]) -> None:
-        """Start tracking batteries status.
-
-        Args:
-            receivers: Map between channel name and receiver for that channel.
-        """
-        select: Select = Select(
-            **receivers,
-        )
-
+    async def _run(self) -> None:
+        """Start tracking batteries status."""
         while True:
             try:
-                await self._update_status(select)
+                await self._update_status(self._select)
             except Exception as err:  # pylint: disable=broad-except
                 _logger.error("BatteriesStatus failed with error: %s. Restart.", err)
 

src/frequenz/sdk/microgrid/_battery/_status.py

@@ -145,6 +145,9 @@ class BatteryStatusTracker:
         InverterComponentState.COMPONENT_STATE_STANDBY,
     }
 
+    # Instance attributes defined outside __init__
+    _select: Optional[Select]
+
     def __init__(  # pylint: disable=too-many-arguments
         self,
         battery_id: int,
@@ -182,6 +185,8 @@ def __init__(  # pylint: disable=too-many-arguments
 
         self._battery = _ComponentData[BatteryData](battery_id)
         self._inverter = _ComponentData[InverterData](inverter_id)
+        # Select needs receivers that can be get in async way only.
+        self._select = None
 
         self._task = asyncio.create_task(
             self._run(status_sender, request_result_receiver)
@@ -198,6 +203,9 @@ def battery_id(self) -> int:
 
     async def stop(self) -> None:
         """Stop tracking battery status."""
+        if self._select is not None:
+            await self._select.stop()
+
         await cancel_and_await(self._task)
 
     async def _run(
@@ -219,16 +227,16 @@ async def _run(
         battery_receiver = await api_client.battery_data(self._battery.component_id)
         inverter_receiver = await api_client.inverter_data(self._inverter.component_id)
 
-        select = Select(
+        self._select = Select(
             battery=battery_receiver,
             inverter=inverter_receiver,
             request_result=request_result_receiver,
         )
 
         while True:
             try:
-                while await select.ready():
-                    new_status = self._update_status(select)
+                while await self._select.ready():
+                    new_status = self._update_status(self._select)
 
                     if new_status is not None:
                         await status_sender.send(new_status)