Add support for last_reset to MQTT sensor (#51036)

* Add support for last_reset to MQTT sensor

* Update abbreviations

* Improve test coverage

homeassistant/components/mqtt/abbreviations.py

@@ -77,6 +77,8 @@ ABBREVIATIONS = {
     "json_attr": "json_attributes",
     "json_attr_t": "json_attributes_topic",
     "json_attr_tpl": "json_attributes_template",
+    "lrst_t": "last_reset_topic",
+    "lrst_val_tpl": "last_reset_value_template",
     "max": "max",
     "min": "min",
     "max_mirs": "max_mireds",

homeassistant/components/mqtt/sensor.py

@@ -3,6 +3,7 @@ from __future__ import annotations
 
 from datetime import timedelta
 import functools
+import logging
 
 import voluptuous as vol
 
@@ -36,7 +37,11 @@ from .mixins import (
     async_setup_entry_helper,
 )
 
+_LOGGER = logging.getLogger(__name__)
+
 CONF_EXPIRE_AFTER = "expire_after"
+CONF_LAST_RESET_TOPIC = "last_reset_topic"
+CONF_LAST_RESET_VALUE_TEMPLATE = "last_reset_value_template"
 CONF_STATE_CLASS = "state_class"
 
 DEFAULT_NAME = "MQTT Sensor"
@@ -46,6 +51,8 @@ PLATFORM_SCHEMA = mqtt.MQTT_RO_PLATFORM_SCHEMA.extend(
         vol.Optional(CONF_DEVICE_CLASS): DEVICE_CLASSES_SCHEMA,
         vol.Optional(CONF_EXPIRE_AFTER): cv.positive_int,
         vol.Optional(CONF_FORCE_UPDATE, default=DEFAULT_FORCE_UPDATE): cv.boolean,
+        vol.Optional(CONF_LAST_RESET_TOPIC): mqtt.valid_subscribe_topic,
+        vol.Optional(CONF_LAST_RESET_VALUE_TEMPLATE): cv.template,
         vol.Optional(CONF_NAME, default=DEFAULT_NAME): cv.string,
         vol.Optional(CONF_STATE_CLASS): STATE_CLASSES_SCHEMA,
         vol.Optional(CONF_UNIT_OF_MEASUREMENT): cv.string,
@@ -79,6 +86,8 @@ async def _async_setup_entity(
 class MqttSensor(MqttEntity, SensorEntity):
     """Representation of a sensor that can be updated using MQTT."""
 
+    _attr_last_reset = None
+
     def __init__(self, hass, config, config_entry, discovery_data):
         """Initialize the sensor."""
         self._state = None
@@ -102,9 +111,13 @@ class MqttSensor(MqttEntity, SensorEntity):
         template = self._config.get(CONF_VALUE_TEMPLATE)
         if template is not None:
             template.hass = self.hass
+        last_reset_template = self._config.get(CONF_LAST_RESET_VALUE_TEMPLATE)
+        if last_reset_template is not None:
+            last_reset_template.hass = self.hass
 
     async def _subscribe_topics(self):
         """(Re)Subscribe to topics."""
+        topics = {}
 
         @callback
         @log_messages(self.hass, self.entity_id)
@@ -140,16 +153,49 @@ class MqttSensor(MqttEntity, SensorEntity):
             self._state = payload
             self.async_write_ha_state()
 
+        topics["state_topic"] = {
+            "topic": self._config[CONF_STATE_TOPIC],
+            "msg_callback": message_received,
+            "qos": self._config[CONF_QOS],
+        }
+
+        @callback
+        @log_messages(self.hass, self.entity_id)
+        def last_reset_message_received(msg):
+            """Handle new last_reset messages."""
+            payload = msg.payload
+
+            template = self._config.get(CONF_LAST_RESET_VALUE_TEMPLATE)
+            if template is not None:
+                variables = {"entity_id": self.entity_id}
+                payload = template.async_render_with_possible_json_value(
+                    payload,
+                    self._state,
+                    variables=variables,
+                )
+            if not payload:
+                _LOGGER.debug("Ignoring empty last_reset message from '%s'", msg.topic)
+                return
+            try:
+                last_reset = dt_util.parse_datetime(payload)
+                if last_reset is None:
+                    raise ValueError
+                self._attr_last_reset = last_reset
+            except ValueError:
+                _LOGGER.warning(
+                    "Invalid last_reset message '%s' from '%s'", msg.payload, msg.topic
+                )
+            self.async_write_ha_state()
+
+        if CONF_LAST_RESET_TOPIC in self._config:
+            topics["state_topic"] = {
+                "topic": self._config[CONF_LAST_RESET_TOPIC],
+                "msg_callback": last_reset_message_received,
+                "qos": self._config[CONF_QOS],
+            }
+
         self._sub_state = await subscription.async_subscribe_topics(
-            self.hass,
+            self.hass, self._sub_state, topics
-            self._sub_state,
-            {
-                "state_topic": {
-                    "topic": self._config[CONF_STATE_TOPIC],
-                    "msg_callback": message_received,
-                    "qos": self._config[CONF_QOS],
-                }
-            },
         )
 
     @callback

tests/components/mqtt/test_sensor.py

@@ -206,6 +206,104 @@ async def test_setting_sensor_value_via_mqtt_json_message(hass, mqtt_mock):
     assert state.state == "100"
 
 
+async def test_setting_sensor_last_reset_via_mqtt_message(hass, mqtt_mock):
+    """Test the setting of the last_reset property via MQTT."""
+    assert await async_setup_component(
+        hass,
+        sensor.DOMAIN,
+        {
+            sensor.DOMAIN: {
+                "platform": "mqtt",
+                "name": "test",
+                "state_topic": "test-topic",
+                "unit_of_measurement": "fav unit",
+                "last_reset_topic": "last-reset-topic",
+            }
+        },
+    )
+    await hass.async_block_till_done()
+
+    async_fire_mqtt_message(hass, "last-reset-topic", "2020-01-02 08:11:00")
+    state = hass.states.get("sensor.test")
+    assert state.attributes.get("last_reset") == "2020-01-02T08:11:00"
+
+
+@pytest.mark.parametrize("datestring", ["2020-21-02 08:11:00", "Hello there!"])
+async def test_setting_sensor_bad_last_reset_via_mqtt_message(
+    hass, caplog, datestring, mqtt_mock
+):
+    """Test the setting of the last_reset property via MQTT."""
+    assert await async_setup_component(
+        hass,
+        sensor.DOMAIN,
+        {
+            sensor.DOMAIN: {
+                "platform": "mqtt",
+                "name": "test",
+                "state_topic": "test-topic",
+                "unit_of_measurement": "fav unit",
+                "last_reset_topic": "last-reset-topic",
+            }
+        },
+    )
+    await hass.async_block_till_done()
+
+    async_fire_mqtt_message(hass, "last-reset-topic", datestring)
+    state = hass.states.get("sensor.test")
+    assert state.attributes.get("last_reset") is None
+    assert "Invalid last_reset message" in caplog.text
+
+
+async def test_setting_sensor_empty_last_reset_via_mqtt_message(
+    hass, caplog, mqtt_mock
+):
+    """Test the setting of the last_reset property via MQTT."""
+    assert await async_setup_component(
+        hass,
+        sensor.DOMAIN,
+        {
+            sensor.DOMAIN: {
+                "platform": "mqtt",
+                "name": "test",
+                "state_topic": "test-topic",
+                "unit_of_measurement": "fav unit",
+                "last_reset_topic": "last-reset-topic",
+            }
+        },
+    )
+    await hass.async_block_till_done()
+
+    async_fire_mqtt_message(hass, "last-reset-topic", "")
+    state = hass.states.get("sensor.test")
+    assert state.attributes.get("last_reset") is None
+    assert "Ignoring empty last_reset message" in caplog.text
+
+
+async def test_setting_sensor_last_reset_via_mqtt_json_message(hass, mqtt_mock):
+    """Test the setting of the value via MQTT with JSON payload."""
+    assert await async_setup_component(
+        hass,
+        sensor.DOMAIN,
+        {
+            sensor.DOMAIN: {
+                "platform": "mqtt",
+                "name": "test",
+                "state_topic": "test-topic",
+                "unit_of_measurement": "fav unit",
+                "last_reset_topic": "last-reset-topic",
+                "last_reset_value_template": "{{ value_json.last_reset }}",
+            }
+        },
+    )
+    await hass.async_block_till_done()
+
+    async_fire_mqtt_message(
+        hass, "last-reset-topic", '{ "last_reset": "2020-01-02 08:11:00" }'
+    )
+    state = hass.states.get("sensor.test")
+    assert state.attributes.get("last_reset") == "2020-01-02T08:11:00"
+
+
 async def test_force_update_disabled(hass, mqtt_mock):
     """Test force update option."""
     assert await async_setup_component(