Add dump service to MQTT integration (#31370)

* Add dump service to MQTT integration

* Lint

homeassistant/components/mqtt/__init__.py

@@ -36,7 +36,7 @@ from homeassistant.exceptions import (
     HomeAssistantError,
     Unauthorized,
 )
-from homeassistant.helpers import config_validation as cv, template
+from homeassistant.helpers import config_validation as cv, event, template
 from homeassistant.helpers.dispatcher import async_dispatcher_connect
 from homeassistant.helpers.entity import Entity
 from homeassistant.helpers.typing import ConfigType, HomeAssistantType, ServiceDataType
@@ -68,6 +68,7 @@ DATA_MQTT_CONFIG = "mqtt_config"
 DATA_MQTT_HASS_CONFIG = "mqtt_hass_config"
 
 SERVICE_PUBLISH = "publish"
+SERVICE_DUMP = "dump"
 
 CONF_EMBEDDED = "embedded"
 
@@ -651,7 +652,7 @@ async def async_setup_entry(hass, entry):
     if result == CONNECTION_FAILED_RECOVERABLE:
         raise ConfigEntryNotReady
 
-    async def async_stop_mqtt(event: Event):
+    async def async_stop_mqtt(_event: Event):
         """Stop MQTT component."""
         await hass.data[DATA_MQTT].async_disconnect()
 
@@ -683,6 +684,40 @@ async def async_setup_entry(hass, entry):
         DOMAIN, SERVICE_PUBLISH, async_publish_service, schema=MQTT_PUBLISH_SCHEMA
     )
 
+    async def async_dump_service(call: ServiceCall):
+        """Handle MQTT dump service calls."""
+        messages = []
+
+        @callback
+        def collect_msg(msg):
+            messages.append((msg.topic, msg.payload.replace("\n", "")))
+
+        unsub = await async_subscribe(hass, call.data["topic"], collect_msg)
+
+        def write_dump():
+            with open(hass.config.path("mqtt_dump.txt"), "wt") as fp:
+                for msg in messages:
+                    fp.write(",".join(msg) + "\n")
+
+        async def finish_dump(_):
+            """Write dump to file."""
+            unsub()
+            await hass.async_add_executor_job(write_dump)
+
+        event.async_call_later(hass, call.data["duration"], finish_dump)
+
+    hass.services.async_register(
+        DOMAIN,
+        SERVICE_DUMP,
+        async_dump_service,
+        schema=vol.Schema(
+            {
+                vol.Required("topic"): valid_subscribe_topic,
+                vol.Optional("duration", default=5): int,
+            }
+        ),
+    )
+
     if conf.get(CONF_DISCOVERY):
         await _async_setup_discovery(
             hass, conf, hass.data[DATA_MQTT_HASS_CONFIG], entry

homeassistant/components/mqtt/services.yaml

@@ -24,3 +24,14 @@ publish:
       description: If message should have the retain flag set.
       example: true
       default: false
+
+dump:
+  description: Dump messages on a topic selector to the 'mqtt_dump.txt' file in your config folder.
+  fields:
+    topic:
+      description: topic to listen to
+      example: "openzwave/#"
+    duration:
+      description: how long we should listen for messages in seconds
+      example: 5
+      default: 5

tests/components/mqtt/test_init.py

@@ -1,4 +1,5 @@
 """The tests for the MQTT component."""
+from datetime import timedelta
 import ssl
 import unittest
 from unittest import mock
@@ -16,10 +17,12 @@ from homeassistant.const import (
 from homeassistant.core import callback
 from homeassistant.exceptions import ConfigEntryNotReady
 from homeassistant.setup import async_setup_component
+from homeassistant.util.dt import utcnow
 
 from tests.common import (
     MockConfigEntry,
     async_fire_mqtt_message,
+    async_fire_time_changed,
     async_mock_mqtt_component,
     fire_mqtt_message,
     get_test_home_assistant,
@@ -803,3 +806,25 @@ async def test_mqtt_ws_subscription(hass, hass_ws_client):
     await client.send_json({"id": 8, "type": "unsubscribe_events", "subscription": 5})
     response = await client.receive_json()
     assert response["success"]
+
+
+async def test_dump_service(hass):
+    """Test that we can dump a topic."""
+    await async_mock_mqtt_component(hass)
+
+    mock_open = mock.mock_open()
+
+    await hass.services.async_call(
+        "mqtt", "dump", {"topic": "bla/#", "duration": 3}, blocking=True
+    )
+    async_fire_mqtt_message(hass, "bla/1", "test1")
+    async_fire_mqtt_message(hass, "bla/2", "test2")
+
+    with mock.patch("homeassistant.components.mqtt.open", mock_open):
+        async_fire_time_changed(hass, utcnow() + timedelta(seconds=3))
+        await hass.async_block_till_done()
+
+    writes = mock_open.return_value.write.mock_calls
+    assert len(writes) == 2
+    assert writes[0][1][0] == "bla/1,test1\n"
+    assert writes[1][1][0] == "bla/2,test2\n"