Add and use percentage constant (#32094)

* Add and use percentage constant

* Fix pylint error and broken test

homeassistant/components/bme680/sensor.py

@@ -8,7 +8,12 @@ from smbus import SMBus  # pylint: disable=import-error
 import voluptuous as vol
 
 from homeassistant.components.sensor import PLATFORM_SCHEMA
-from homeassistant.const import CONF_MONITORED_CONDITIONS, CONF_NAME, TEMP_FAHRENHEIT
+from homeassistant.const import (
+    CONF_MONITORED_CONDITIONS,
+    CONF_NAME,
+    TEMP_FAHRENHEIT,
+    UNIT_PERCENTAGE,
+)
 import homeassistant.helpers.config_validation as cv
 from homeassistant.helpers.entity import Entity
 from homeassistant.util.temperature import celsius_to_fahrenheit
@@ -50,10 +55,10 @@ SENSOR_GAS = "gas"
 SENSOR_AQ = "airquality"
 SENSOR_TYPES = {
     SENSOR_TEMP: ["Temperature", None],
-    SENSOR_HUMID: ["Humidity", "%"],
+    SENSOR_HUMID: ["Humidity", UNIT_PERCENTAGE],
     SENSOR_PRESS: ["Pressure", "mb"],
     SENSOR_GAS: ["Gas Resistance", "Ohms"],
-    SENSOR_AQ: ["Air Quality", "%"],
+    SENSOR_AQ: ["Air Quality", UNIT_PERCENTAGE],
 }
 DEFAULT_MONITORED = [SENSOR_TEMP, SENSOR_HUMID, SENSOR_PRESS, SENSOR_AQ]
 OVERSAMPLING_VALUES = set([0, 1, 2, 4, 8, 16])