More support for availability reporting on MQTT components (#11336)

* Abstract MQTT availability from individual components

- Moved availability topic and payloads to MQTT base schema.
- Updated components that already report availability:
  - Switch
  - Binary sensor
  - Cover

* Add availability reporting to additional MQTT components

- Light
- JSON light
- Template light
- Lock
- Fan
- HVAC
- Sensor
- Vacuum
- Alarm control panel

* Annotate MQTT platform coroutines

tests/components/lock/test_mqtt.py

@@ -2,8 +2,8 @@
 import unittest
 
 from homeassistant.setup import setup_component
-from homeassistant.const import (STATE_LOCKED, STATE_UNLOCKED,
-                                 ATTR_ASSUMED_STATE)
+from homeassistant.const import (
+    STATE_LOCKED, STATE_UNLOCKED, STATE_UNAVAILABLE, ATTR_ASSUMED_STATE)
 import homeassistant.components.lock as lock
 from tests.common import (
     mock_mqtt_component, fire_mqtt_message, get_test_home_assistant)
@@ -111,3 +111,34 @@ class TestLockMQTT(unittest.TestCase):
 
         state = self.hass.states.get('lock.test')
         self.assertEqual(STATE_UNLOCKED, state.state)
+
+    def test_custom_availability_payload(self):
+        """Test availability by custom payload with defined topic."""
+        self.assertTrue(setup_component(self.hass, lock.DOMAIN, {
+            lock.DOMAIN: {
+                'platform': 'mqtt',
+                'name': 'test',
+                'state_topic': 'state-topic',
+                'command_topic': 'command-topic',
+                'payload_lock': 'LOCK',
+                'payload_unlock': 'UNLOCK',
+                'availability_topic': 'availability-topic',
+                'payload_available': 'good',
+                'payload_not_available': 'nogood'
+            }
+        }))
+
+        state = self.hass.states.get('lock.test')
+        self.assertEqual(STATE_UNAVAILABLE, state.state)
+
+        fire_mqtt_message(self.hass, 'availability-topic', 'good')
+        self.hass.block_till_done()
+
+        state = self.hass.states.get('lock.test')
+        self.assertNotEqual(STATE_UNAVAILABLE, state.state)
+
+        fire_mqtt_message(self.hass, 'availability-topic', 'nogood')
+        self.hass.block_till_done()
+
+        state = self.hass.states.get('lock.test')
+        self.assertEqual(STATE_UNAVAILABLE, state.state)