Improve log message when zone missing in geolocation trigger (#51522)

* log warning message if zone cannot be found

* improve log message

* add test case

homeassistant/components/geo_location/trigger.py

@@ -1,4 +1,6 @@
 """Offer geolocation automation rules."""
+import logging
+
 import voluptuous as vol
 
 from homeassistant.components.geo_location import DOMAIN
@@ -10,6 +12,8 @@ from homeassistant.helpers.event import TrackStates, async_track_state_change_fi
 
 # mypy: allow-untyped-defs, no-check-untyped-defs
 
+_LOGGER = logging.getLogger(__name__)
+
 EVENT_ENTER = "enter"
 EVENT_LEAVE = "leave"
 DEFAULT_EVENT = EVENT_ENTER
@@ -49,6 +53,13 @@ async def async_attach_trigger(hass, config, action, automation_info):
             return
 
         zone_state = hass.states.get(zone_entity_id)
+        if zone_state is None:
+            _LOGGER.warning(
+                "Unable to execute automation %s: Zone %s not found",
+                automation_info["name"],
+                zone_entity_id,
+            )
+            return
 
         from_match = (
             condition.zone(hass, zone_state, from_state) if from_state else False

tests/components/geo_location/test_trigger.py

@@ -1,4 +1,6 @@
 """The tests for the geolocation trigger."""
+import logging
+
 import pytest
 
 from homeassistant.components import automation, zone
@@ -318,3 +320,46 @@ async def test_if_fires_on_zone_disappear(hass, calls):
     assert (
         calls[0].data["some"] == "geo_location - geo_location.entity - hello -  - test"
     )
+
+
+async def test_zone_undefined(hass, calls, caplog):
+    """Test for undefined zone."""
+    hass.states.async_set(
+        "geo_location.entity",
+        "hello",
+        {"latitude": 32.880586, "longitude": -117.237564, "source": "test_source"},
+    )
+    await hass.async_block_till_done()
+
+    caplog.set_level(logging.WARNING)
+
+    zone_does_not_exist = "zone.does_not_exist"
+    assert await async_setup_component(
+        hass,
+        automation.DOMAIN,
+        {
+            automation.DOMAIN: {
+                "trigger": {
+                    "platform": "geo_location",
+                    "source": "test_source",
+                    "zone": zone_does_not_exist,
+                    "event": "leave",
+                },
+                "action": {"service": "test.automation"},
+            }
+        },
+    )
+
+    hass.states.async_set(
+        "geo_location.entity",
+        "hello",
+        {"latitude": 32.881011, "longitude": -117.234758, "source": "test_source"},
+    )
+    await hass.async_block_till_done()
+
+    assert len(calls) == 0
+
+    assert (
+        f"Unable to execute automation automation 0: Zone {zone_does_not_exist} not found"
+        in caplog.text
+    )