Support mqtt discovery topic prefix with slashes (#24840)

homeassistant/components/mqtt/discovery.py

@@ -15,8 +15,8 @@ from .const import ATTR_DISCOVERY_HASH, CONF_STATE_TOPIC
 _LOGGER = logging.getLogger(__name__)
 
 TOPIC_MATCHER = re.compile(
-    r'(?P<prefix_topic>\w+)/(?P<component>\w+)/'
-    r'(?:(?P<node_id>[a-zA-Z0-9_-]+)/)?(?P<object_id>[a-zA-Z0-9_-]+)/config')
+    r'(?P<component>\w+)/(?:(?P<node_id>[a-zA-Z0-9_-]+)/)'
+    r'?(?P<object_id>[a-zA-Z0-9_-]+)/config')
 
 SUPPORTED_COMPONENTS = [
     'alarm_control_panel',
@@ -233,12 +233,13 @@ async def async_start(hass: HomeAssistantType, discovery_topic, hass_config,
         """Process the received message."""
         payload = msg.payload
         topic = msg.topic
-        match = TOPIC_MATCHER.match(topic)
+        topic_trimmed = topic.replace('{}/'.format(discovery_topic), '', 1)
+        match = TOPIC_MATCHER.match(topic_trimmed)
 
         if not match:
             return
 
-        _prefix_topic, component, node_id, object_id = match.groups()
+        component, node_id, object_id = match.groups()
 
         if component not in SUPPORTED_COMPONENTS:
             _LOGGER.warning("Component %s is not supported", component)

tests/components/mqtt/test_discovery.py

@@ -369,3 +369,21 @@ async def test_no_implicit_state_topic_switch(hass, mqtt_mock, caplog):
 
     state = hass.states.get('switch.Test1')
     assert state.state == 'off'
+
+
+async def test_complex_discovery_topic_prefix(hass, mqtt_mock, caplog):
+    """Tests handling of discovery topic prefix with multiple slashes."""
+    entry = MockConfigEntry(domain=mqtt.DOMAIN)
+
+    await async_start(hass, 'my_home/homeassistant/register', {}, entry)
+
+    async_fire_mqtt_message(hass, ('my_home/homeassistant/register'
+                                   '/binary_sensor/node1/object1/config'),
+                            '{ "name": "Beer" }')
+    await hass.async_block_till_done()
+
+    state = hass.states.get('binary_sensor.beer')
+
+    assert state is not None
+    assert state.name == 'Beer'
+    assert ('binary_sensor', 'node1 object1') in hass.data[ALREADY_DISCOVERED]