Check if the Brother printer serial number matches (#155842)

homeassistant/components/brother/__init__.py

@@ -9,7 +9,7 @@ from brother import Brother, SnmpError
 from homeassistant.components.snmp import async_get_snmp_engine
 from homeassistant.const import CONF_HOST, CONF_PORT, CONF_TYPE, Platform
 from homeassistant.core import HomeAssistant
-from homeassistant.exceptions import ConfigEntryNotReady
+from homeassistant.exceptions import ConfigEntryError, ConfigEntryNotReady
 
 from .const import (
     CONF_COMMUNITY,
@@ -50,6 +50,15 @@ async def async_setup_entry(hass: HomeAssistant, entry: BrotherConfigEntry) -> b
     coordinator = BrotherDataUpdateCoordinator(hass, entry, brother)
     await coordinator.async_config_entry_first_refresh()
 
+    if brother.serial.lower() != entry.unique_id:
+        raise ConfigEntryError(
+            translation_domain=DOMAIN,
+            translation_key="serial_mismatch",
+            translation_placeholders={
+                "device": entry.title,
+            },
+        )
+
     entry.runtime_data = coordinator
 
     await hass.config_entries.async_forward_entry_setups(entry, PLATFORMS)

homeassistant/components/brother/strings.json

@@ -207,6 +207,9 @@
     "cannot_connect": {
       "message": "An error occurred while connecting to the {device} printer: {error}"
     },
+    "serial_mismatch": {
+      "message": "The serial number for {device} doesn't match the one in the configuration. It's possible that the two Brother printers have swapped IP addresses. Restore the previous IP address configuration or reconfigure the devices with Home Assistant."
+    },
     "update_error": {
       "message": "An error occurred while retrieving data from the {device} printer: {error}"
     }

tests/components/brother/test_init.py

@@ -98,3 +98,17 @@ async def test_migrate_entry(
     assert config_entry.minor_version == 2
     assert config_entry.data[SECTION_ADVANCED_SETTINGS][CONF_PORT] == 161
     assert config_entry.data[SECTION_ADVANCED_SETTINGS][CONF_COMMUNITY] == "public"
+
+
+async def test_serial_mismatch(
+    hass: HomeAssistant,
+    mock_config_entry: MockConfigEntry,
+    mock_brother: AsyncMock,
+    mock_brother_client: AsyncMock,
+) -> None:
+    """Test if the serial number matches on init."""
+    mock_brother_client.serial = "DIFFERENT_SERIAL"
+
+    await init_integration(hass, mock_config_entry)
+
+    assert mock_config_entry.state is ConfigEntryState.SETUP_ERROR