Migrate to voluptuous (#3174)

homeassistant/components/sensor/steam_online.py

@@ -4,12 +4,24 @@ Sensor for Steam account status.
 For more details about this platform, please refer to the documentation at
 https://home-assistant.io/components/sensor.steam_online/
 """
+import voluptuous as vol
+
+from homeassistant.components.sensor import PLATFORM_SCHEMA
 from homeassistant.helpers.entity import Entity
 from homeassistant.const import CONF_API_KEY
+import homeassistant.helpers.config_validation as cv
+
+REQUIREMENTS = ['steamodd==4.21']
+
+CONF_ACCOUNTS = 'accounts'
 
 ICON = 'mdi:steam'
 
-REQUIREMENTS = ['steamodd==4.21']
+PLATFORM_SCHEMA = PLATFORM_SCHEMA.extend({
+    vol.Required(CONF_API_KEY): cv.string,
+    vol.Required(CONF_ACCOUNTS, default=[]):
+        vol.All(cv.ensure_list, [cv.string]),
+})
 
 
 # pylint: disable=unused-argument
@@ -19,7 +31,7 @@ def setup_platform(hass, config, add_devices, discovery_info=None):
     steamod.api.key.set(config.get(CONF_API_KEY))
     add_devices(
         [SteamSensor(account,
-                     steamod) for account in config.get('accounts', [])])
+                     steamod) for account in config.get(CONF_ACCOUNTS)])
 
 
 class SteamSensor(Entity):