Add state selector (#77024)

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

homeassistant/helpers/selector.py

@@ -741,6 +741,30 @@ class TargetSelectorConfig(TypedDict, total=False):
     device: SingleDeviceSelectorConfig
 
 
+class StateSelectorConfig(TypedDict):
+    """Class to represent an state selector config."""
+
+    entity_id: str
+
+
+@SELECTORS.register("state")
+class StateSelector(Selector):
+    """Selector for an entity state."""
+
+    selector_type = "state"
+
+    CONFIG_SCHEMA = vol.Schema({vol.Required("entity_id"): cv.entity_id})
+
+    def __init__(self, config: StateSelectorConfig) -> None:
+        """Instantiate a selector."""
+        super().__init__(config)
+
+    def __call__(self, data: Any) -> str:
+        """Validate the passed selection."""
+        state: str = vol.Schema(str)(data)
+        return state
+
+
 @SELECTORS.register("target")
 class TargetSelector(Selector):
     """Selector of a target value (area ID, device ID, entity ID etc).

tests/helpers/test_selector.py

@@ -294,6 +294,21 @@ def test_time_selector_schema(schema, valid_selections, invalid_selections):
     _test_selector("time", schema, valid_selections, invalid_selections)
 
 
+@pytest.mark.parametrize(
+    "schema,valid_selections,invalid_selections",
+    (
+        (
+            {"entity_id": "sensor.abc"},
+            ("on", "armed"),
+            (None, True, 1),
+        ),
+    ),
+)
+def test_state_selector_schema(schema, valid_selections, invalid_selections):
+    """Test state selector."""
+    _test_selector("state", schema, valid_selections, invalid_selections)
+
+
 @pytest.mark.parametrize(
     "schema,valid_selections,invalid_selections",
     (