Always setup demo platforms with device support from config entry (#94586)

* Always setup demo platforms with device support from config entry

* Adjust test fixutres

* Update tests depending on the demo integration

homeassistant/components/demo/datetime.py

@@ -5,22 +5,19 @@ from datetime import datetime, timezone
 
 from homeassistant.components.datetime import DateTimeEntity
 from homeassistant.config_entries import ConfigEntry
-from homeassistant.const import DEVICE_DEFAULT_NAME
 from homeassistant.core import HomeAssistant
 from homeassistant.helpers.entity import DeviceInfo
 from homeassistant.helpers.entity_platform import AddEntitiesCallback
-from homeassistant.helpers.typing import ConfigType, DiscoveryInfoType
 
 from . import DOMAIN
 
 
-async def async_setup_platform(
+async def async_setup_entry(
     hass: HomeAssistant,
-    config: ConfigType,
+    config_entry: ConfigEntry,
     async_add_entities: AddEntitiesCallback,
-    discovery_info: DiscoveryInfoType | None = None,
 ) -> None:
-    """Set up the Demo date/time entity."""
+    """Set up the demo datetime platform."""
     async_add_entities(
         [
             DemoDateTime(
@@ -34,24 +31,16 @@ async def async_setup_platform(
     )
 
 
-async def async_setup_entry(
-    hass: HomeAssistant,
-    config_entry: ConfigEntry,
-    async_add_entities: AddEntitiesCallback,
-) -> None:
-    """Set up the Demo config entry."""
-    await async_setup_platform(hass, {}, async_add_entities)
-
-
 class DemoDateTime(DateTimeEntity):
     """Representation of a Demo date/time entity."""
 
+    _attr_has_entity_name = True
     _attr_should_poll = False
 
     def __init__(
         self,
         unique_id: str,
-        name: str,
+        device_name: str,
         state: datetime,
         icon: str,
         assumed_state: bool,
@@ -59,7 +48,6 @@ class DemoDateTime(DateTimeEntity):
         """Initialize the Demo date/time entity."""
         self._attr_assumed_state = assumed_state
         self._attr_icon = icon
-        self._attr_name = name or DEVICE_DEFAULT_NAME
         self._attr_native_value = state
         self._attr_unique_id = unique_id
 
@@ -68,7 +56,7 @@ class DemoDateTime(DateTimeEntity):
                 # Serial numbers are unique identifiers within a specific domain
                 (DOMAIN, unique_id)
             },
-            name=self.name,
+            name=device_name,
         )
 
     async def async_set_value(self, value: datetime) -> None: