Config validation for automation MQTT trigger

homeassistant/components/automation/mqtt.py

@@ -4,26 +4,29 @@
 For more details about this automation rule, please refer to the documentation
 at https://home-assistant.io/components/automation/#mqtt-trigger
 """
-import logging
+import voluptuous as vol
 
 import homeassistant.components.mqtt as mqtt
+from homeassistant.const import CONF_PLATFORM
+import homeassistant.helpers.config_validation as cv
 
 DEPENDENCIES = ['mqtt']
 
 CONF_TOPIC = 'topic'
 CONF_PAYLOAD = 'payload'
 
+TRIGGER_SCHEMA = vol.Schema({
+    vol.Required(CONF_PLATFORM): mqtt.DOMAIN,
+    vol.Required(CONF_TOPIC): mqtt.valid_subscribe_topic,
+    vol.Optional(CONF_PAYLOAD): cv.string,
+})
+
 
 def trigger(hass, config, action):
     """Listen for state changes based on configuration."""
-    topic = config.get(CONF_TOPIC)
+    topic = config[CONF_TOPIC]
     payload = config.get(CONF_PAYLOAD)
 
-    if topic is None:
-        logging.getLogger(__name__).error(
-            "Missing configuration key %s", CONF_TOPIC)
-        return False
-
     def mqtt_automation_listener(msg_topic, msg_payload, qos):
         """Listen for MQTT messages."""
         if payload is None or payload == msg_payload: