Migrate demo notify platform (#115448)

* Migrate demo notify platform

* Update homeassistant/components/demo/notify.py

Co-authored-by: Paulus Schoutsen <balloob@gmail.com>

* Remove no needed tests

* Cleanup redundant attribute assignment

---------

Co-authored-by: Paulus Schoutsen <balloob@gmail.com>

homeassistant/components/demo/notify.py

@@ -1,38 +1,44 @@
-"""Demo notification service."""
+"""Demo notification entity."""
 
 from __future__ import annotations
 
-from typing import Any
-
-from homeassistant.components.notify import BaseNotificationService
+from homeassistant.components.notify import DOMAIN, NotifyEntity
+from homeassistant.config_entries import ConfigEntry
 from homeassistant.core import HomeAssistant
-from homeassistant.helpers.typing import ConfigType, DiscoveryInfoType
+from homeassistant.helpers.device_registry import DeviceInfo
+from homeassistant.helpers.entity_platform import AddEntitiesCallback
 
 EVENT_NOTIFY = "notify"
 
 
-def get_service(
+async def async_setup_entry(
     hass: HomeAssistant,
-    config: ConfigType,
-    discovery_info: DiscoveryInfoType | None = None,
-) -> BaseNotificationService:
-    """Get the demo notification service."""
-    return DemoNotificationService(hass)
+    config_entry: ConfigEntry,
+    async_add_entities: AddEntitiesCallback,
+) -> None:
+    """Set up the demo entity platform."""
+    async_add_entities([DemoNotifyEntity(unique_id="notify", device_name="Notifier")])
 
 
-class DemoNotificationService(BaseNotificationService):
-    """Implement demo notification service."""
+class DemoNotifyEntity(NotifyEntity):
+    """Implement demo notification platform."""
 
-    def __init__(self, hass: HomeAssistant) -> None:
-        """Initialize the service."""
-        self.hass = hass
+    _attr_has_entity_name = True
+    _attr_name = None
 
-    @property
-    def targets(self) -> dict[str, str]:
-        """Return a dictionary of registered targets."""
-        return {"test target name": "test target id"}
+    def __init__(
+        self,
+        unique_id: str,
+        device_name: str,
+    ) -> None:
+        """Initialize the Demo button entity."""
+        self._attr_unique_id = unique_id
+        self._attr_device_info = DeviceInfo(
+            identifiers={(DOMAIN, unique_id)},
+            name=device_name,
+        )
 
-    def send_message(self, message: str = "", **kwargs: Any) -> None:
+    async def async_send_message(self, message: str) -> None:
         """Send a message to a user."""
-        kwargs["message"] = message
-        self.hass.bus.fire(EVENT_NOTIFY, kwargs)
+        event_notitifcation = {"message": message}
+        self.hass.bus.async_fire(EVENT_NOTIFY, event_notitifcation)