siren: fix is_on to return boolean as expected

- Implemented test for siren.is_on, which was missing coverage.
- Discovered from tests that it was returning a string, the string "off" is not False.

custom_components/tuya_local/generic/siren.py

@@ -52,7 +52,7 @@ class TuyaLocalSiren(TuyaLocalEntity, SirenEntity):
     def is_on(self):
         """Return whether the siren is on."""
         if self._tone_dp:
-            return self._tone_dp.get_value(self._device)
+            return self._tone_dp.get_value(self._device) != "off"
 
     async def async_turn_on(self, **kwargs) -> None:
         tone = kwargs.get("tone", None)

tests/devices/test_orion_outdoor_siren.py

@@ -150,6 +150,25 @@ class TestOrionSiren(MultiBinarySensorTests, BasicSensorTests, TuyaDeviceTestCas
         ):
             await self.subject.async_turn_on(tone="sound", duration=4, volume=0.9)
 
+    async def test_turn_on_keeps_tone_when_already_on(self):
+        """Test calling turn_on without a tone parameter when the siren is on"""
+        self.dps[TONE_DP] = "alarm_light"
+        async with assert_device_properties_set(
+            self.subject._device, {VOLUME_DP: "low", TONE_DP: "alarm_light"}
+        ):
+            await self.subject.async_turn_on(volume=0.5)
+
+    def test_is_on(self):
+        """Test the is_on property"""
+        self.dps[TONE_DP] = "normal"
+        self.assertFalse(self.subject.is_on)
+        self.dps[TONE_DP] = "alarm_light"
+        self.assertTrue(self.subject.is_on)
+        self.dps[TONE_DP] = "alarm_sound"
+        self.assertTrue(self.subject.is_on)
+        self.dps[TONE_DP] = "alarm_sound_light"
+        self.assertTrue(self.subject.is_on)
+
     def test_extra_attributes(self):
         """Test reading the extra attributes from the siren"""
         self.dps[TONE_DP] = "alarm_light"