Add capability-attributes (#29306)

tests/helpers/test_entity.py

@@ -9,7 +9,7 @@ import pytest
 
 from homeassistant.helpers import entity, entity_registry
 from homeassistant.core import Context
-from homeassistant.const import ATTR_HIDDEN, ATTR_DEVICE_CLASS
+from homeassistant.const import ATTR_HIDDEN, ATTR_DEVICE_CLASS, STATE_UNAVAILABLE
 from homeassistant.config import DATA_CUSTOMIZE
 from homeassistant.helpers.entity_values import EntityValues
 
@@ -641,3 +641,23 @@ async def test_disabled_in_entity_registry(hass):
     assert entry3 != entry2
     assert ent.registry_entry == entry3
     assert ent.enabled is False
+
+
+async def test_capability_attrs(hass):
+    """Test we still include capabilities even when unavailable."""
+    with patch.object(
+        entity.Entity, "available", PropertyMock(return_value=False)
+    ), patch.object(
+        entity.Entity,
+        "capability_attributes",
+        PropertyMock(return_value={"always": "there"}),
+    ):
+        ent = entity.Entity()
+        ent.hass = hass
+        ent.entity_id = "hello.world"
+        ent.async_write_ha_state()
+
+    state = hass.states.get("hello.world")
+    assert state is not None
+    assert state.state == STATE_UNAVAILABLE
+    assert state.attributes["always"] == "there"