From d3bc2bc47f30cb6f33aca6126a06b3ad102b8351 Mon Sep 17 00:00:00 2001
From: Franck Nijhof <git@frenck.dev>
Date: Sat, 22 May 2021 18:20:34 +0200
Subject: [PATCH] Define binary_sensor entity attribute as class variables
 (#50940)

---
 homeassistant/components/binary_sensor/__init__.py | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/homeassistant/components/binary_sensor/__init__.py b/homeassistant/components/binary_sensor/__init__.py
index f022509f9de..9bf53407b38 100644
--- a/homeassistant/components/binary_sensor/__init__.py
+++ b/homeassistant/components/binary_sensor/__init__.py
@@ -1,4 +1,5 @@
 """Component to interface with binary sensors."""
+from __future__ import annotations
 
 from datetime import timedelta
 import logging
@@ -12,6 +13,7 @@ from homeassistant.helpers.config_validation import (  # noqa: F401
 )
 from homeassistant.helpers.entity import Entity
 from homeassistant.helpers.entity_component import EntityComponent
+from homeassistant.helpers.typing import StateType
 
 # mypy: allow-untyped-defs, no-check-untyped-defs
 
@@ -147,21 +149,18 @@ async def async_unload_entry(hass, entry):
 class BinarySensorEntity(Entity):
     """Represent a binary sensor."""
 
+    _attr_is_on: bool | None = None
+
     @property
-    def is_on(self):
+    def is_on(self) -> bool | None:
         """Return true if the binary sensor is on."""
         return None
 
     @property
-    def state(self):
+    def state(self) -> StateType:
         """Return the state of the binary sensor."""
         return STATE_ON if self.is_on else STATE_OFF
 
-    @property
-    def device_class(self):
-        """Return the class of this device, from component DEVICE_CLASSES."""
-        return None
-
 
 class BinarySensorDevice(BinarySensorEntity):
     """Represent a binary sensor (for backwards compatibility)."""