Calculate _attr_native_value when no restore state and appliance is running in Whirlpool (#88559)

* Initialize _attr_native_value when running

* Fix return type on update_sensor_state()
move init at startup if _attr_native_value is None

* allow update _attr_native_value when running and none

homeassistant/components/whirlpool/sensor.py

@@ -290,12 +290,15 @@ class WasherDryerTimeClass(RestoreSensor):
 
         if machine_state is MachineState.RunningMainCycle:
             self._running = True
+
             new_timestamp = now + timedelta(
                 seconds=int(self._wd.get_attribute("Cavity_TimeStatusEstTimeRemaining"))
             )
 
-            if isinstance(self._attr_native_value, datetime) and abs(
-                new_timestamp - self._attr_native_value
-            ) > timedelta(seconds=60):
+            if (
+                isinstance(self._attr_native_value, datetime)
+                and abs(new_timestamp - self._attr_native_value) > timedelta(seconds=60)
+                or self._attr_native_value is None
+            ):
                 self._attr_native_value = new_timestamp
                 self._async_write_ha_state()

tests/components/whirlpool/test_sensor.py

@@ -17,7 +17,7 @@ async def update_sensor_state(
     hass: HomeAssistant,
     entity_id: str,
     mock_sensor_api_instance: MagicMock,
-) -> None:
+) -> State:
     """Simulate an update trigger from the API."""
 
     for call in mock_sensor_api_instance.register_attr_callback.call_args_list:
@@ -300,6 +300,23 @@ async def test_restore_state(
     assert state.state == thetimestamp.isoformat()
 
 
+async def test_no_restore_state(
+    hass: HomeAssistant,
+    mock_sensor_api_instances: MagicMock,
+    mock_sensor1_api: MagicMock,
+) -> None:
+    """Test sensor restore state with no restore."""
+    # create and add entry
+    entity_id = "sensor.washer_end_time"
+    await init_integration(hass)
+    # restore from cache
+    state = hass.states.get(entity_id)
+    state.state = "unknown"
+
+    state = await update_sensor_state(hass, entity_id, mock_sensor1_api)
+    state.state = datetime.now().isoformat()
+
+
 async def test_callback(
     hass: HomeAssistant,
     mock_sensor_api_instances: MagicMock,