Add unique_id for mqtt binary sensor (#14929)

* Added unique_id for mqtt binary sensor

* Added missing mqtt message fire in test

homeassistant/components/binary_sensor/mqtt.py

@@ -6,6 +6,7 @@ https://home-assistant.io/components/binary_sensor.mqtt/
 """
 import asyncio
 import logging
+from typing import Optional
 
 import voluptuous as vol
 
@@ -24,7 +25,7 @@ import homeassistant.helpers.config_validation as cv
 _LOGGER = logging.getLogger(__name__)
 
 DEFAULT_NAME = 'MQTT Binary sensor'
-
+CONF_UNIQUE_ID = 'unique_id'
 DEFAULT_PAYLOAD_OFF = 'OFF'
 DEFAULT_PAYLOAD_ON = 'ON'
 DEFAULT_FORCE_UPDATE = False
@@ -37,6 +38,9 @@ PLATFORM_SCHEMA = mqtt.MQTT_RO_PLATFORM_SCHEMA.extend({
     vol.Optional(CONF_PAYLOAD_ON, default=DEFAULT_PAYLOAD_ON): cv.string,
     vol.Optional(CONF_DEVICE_CLASS): DEVICE_CLASSES_SCHEMA,
     vol.Optional(CONF_FORCE_UPDATE, default=DEFAULT_FORCE_UPDATE): cv.boolean,
+    # Integrations shouldn't never expose unique_id through configuration
+    # this here is an exception because MQTT is a msg transport, not a protocol
+    vol.Optional(CONF_UNIQUE_ID): cv.string,
 }).extend(mqtt.MQTT_AVAILABILITY_SCHEMA.schema)
 
 
@@ -61,7 +65,8 @@ def async_setup_platform(hass, config, async_add_devices, discovery_info=None):
         config.get(CONF_PAYLOAD_OFF),
         config.get(CONF_PAYLOAD_AVAILABLE),
         config.get(CONF_PAYLOAD_NOT_AVAILABLE),
-        value_template
+        value_template,
+        config.get(CONF_UNIQUE_ID),
     )])
 
 
@@ -70,7 +75,8 @@ class MqttBinarySensor(MqttAvailability, BinarySensorDevice):
 
     def __init__(self, name, state_topic, availability_topic, device_class,
                  qos, force_update, payload_on, payload_off, payload_available,
-                 payload_not_available, value_template):
+                 payload_not_available, value_template,
+                 unique_id: Optional[str]):
         """Initialize the MQTT binary sensor."""
         super().__init__(availability_topic, qos, payload_available,
                          payload_not_available)
@@ -83,6 +89,7 @@ class MqttBinarySensor(MqttAvailability, BinarySensorDevice):
         self._qos = qos
         self._force_update = force_update
         self._template = value_template
+        self._unique_id = unique_id
 
     @asyncio.coroutine
     def async_added_to_hass(self):
@@ -134,3 +141,8 @@ class MqttBinarySensor(MqttAvailability, BinarySensorDevice):
     def force_update(self):
         """Force update."""
         return self._force_update
+
+    @property
+    def unique_id(self):
+        """Return a unique ID."""
+        return self._unique_id

tests/components/binary_sensor/test_mqtt.py

@@ -77,6 +77,25 @@ class TestSensorMQTT(unittest.TestCase):
         state = self.hass.states.get('binary_sensor.test')
         self.assertIsNone(state)
 
+    def test_unique_id(self):
+        """Test unique id option only creates one sensor per unique_id."""
+        assert setup_component(self.hass, binary_sensor.DOMAIN, {
+            binary_sensor.DOMAIN: [{
+                'platform': 'mqtt',
+                'name': 'Test 1',
+                'state_topic': 'test-topic',
+                'unique_id': 'TOTALLY_UNIQUE'
+            }, {
+                'platform': 'mqtt',
+                'name': 'Test 2',
+                'state_topic': 'test-topic',
+                'unique_id': 'TOTALLY_UNIQUE'
+            }]
+        })
+        fire_mqtt_message(self.hass, 'test-topic', 'payload')
+        self.hass.block_till_done()
+        assert len(self.hass.states.all()) == 1
+
     def test_availability_without_topic(self):
         """Test availability without defined availability topic."""
         self.assertTrue(setup_component(self.hass, binary_sensor.DOMAIN, {