Mend incorrectly imported MQTT config entries (#68987)

Co-authored-by: Paulus Schoutsen <balloob@gmail.com>

tests/components/mqtt/test_init.py

@@ -23,7 +23,7 @@ from homeassistant.const import (
     TEMP_CELSIUS,
 )
 import homeassistant.core as ha
-from homeassistant.core import CoreState, callback
+from homeassistant.core import CoreState, HomeAssistant, callback
 from homeassistant.exceptions import HomeAssistantError
 from homeassistant.helpers import device_registry as dr, template
 from homeassistant.helpers.entity import Entity
@@ -1620,6 +1620,57 @@ async def test_setup_entry_with_config_override(hass, device_reg, mqtt_client_mo
     assert device_entry is not None
 
 
+async def test_update_incomplete_entry(
+    hass: HomeAssistant, device_reg, mqtt_client_mock, caplog
+):
+    """Test if the MQTT component loads when config entry data is incomplete."""
+    data = (
+        '{ "device":{"identifiers":["0AFFD2"]},'
+        '  "state_topic": "foobar/sensor",'
+        '  "unique_id": "unique" }'
+    )
+
+    # Config entry data is incomplete
+    entry = MockConfigEntry(domain=mqtt.DOMAIN, data={"port": 1234})
+    entry.add_to_hass(hass)
+    # Mqtt present in yaml config
+    config = {"broker": "yaml_broker"}
+    await async_setup_component(hass, mqtt.DOMAIN, {mqtt.DOMAIN: config})
+    await hass.async_block_till_done()
+
+    # Config entry data should now be updated
+    assert entry.data == {
+        "port": 1234,
+        "broker": "yaml_broker",
+    }
+    # Warnings about broker deprecated, but not about other keys with default values
+    assert (
+        "The 'broker' option is deprecated, please remove it from your configuration"
+        in caplog.text
+    )
+    assert (
+        "Deprecated configuration settings found in configuration.yaml. These settings "
+        "from your configuration entry will override: {'broker': 'yaml_broker'}"
+        in caplog.text
+    )
+
+    # Discover a device to verify the entry was setup correctly
+    async_fire_mqtt_message(hass, "homeassistant/sensor/bla/config", data)
+    await hass.async_block_till_done()
+
+    device_entry = device_reg.async_get_device({("mqtt", "0AFFD2")})
+    assert device_entry is not None
+
+
+async def test_fail_no_broker(hass, device_reg, mqtt_client_mock, caplog):
+    """Test if the MQTT component loads when broker configuration is missing."""
+    # Config entry data is incomplete
+    entry = MockConfigEntry(domain=mqtt.DOMAIN, data={})
+    entry.add_to_hass(hass)
+    assert not await hass.config_entries.async_setup(entry.entry_id)
+    assert "MQTT broker is not configured, please configure it" in caplog.text
+
+
 @pytest.mark.no_fail_on_log_exception
 async def test_message_callback_exception_gets_logged(hass, caplog, mqtt_mock):
     """Test exception raised by message handler."""