Allow specifying template entities based on triggers (#48169)

Co-authored-by: Martin Hjelmare <marhje52@gmail.com>

tests/components/template/test_sensor.py

@@ -15,8 +15,10 @@ from homeassistant.const import (
     STATE_OFF,
     STATE_ON,
     STATE_UNAVAILABLE,
+    STATE_UNKNOWN,
 )
-from homeassistant.core import CoreState, callback
+from homeassistant.core import Context, CoreState, callback
+from homeassistant.helpers import entity_registry
 from homeassistant.helpers.template import Template
 from homeassistant.setup import ATTR_COMPONENT, async_setup_component
 import homeassistant.util.dt as dt_util
@@ -986,3 +988,126 @@ async def test_duplicate_templates(hass):
     state = hass.states.get("sensor.test_template_sensor")
     assert state.attributes["friendly_name"] == "Def"
     assert state.state == "Def"
+
+
+async def test_trigger_entity(hass):
+    """Test trigger entity works."""
+    assert await async_setup_component(
+        hass,
+        "template",
+        {
+            "template": [
+                {"invalid": "config"},
+                # This one should still be set up
+                {
+                    "unique_id": "listening-test-event",
+                    "trigger": {"platform": "event", "event_type": "test_event"},
+                    "sensors": {
+                        "hello": {
+                            "friendly_name": "Hello Name",
+                            "unique_id": "just_a_test",
+                            "device_class": "battery",
+                            "unit_of_measurement": "%",
+                            "value_template": "{{ trigger.event.data.beer }}",
+                            "entity_picture_template": "{{ '/local/dogs.png' }}",
+                            "icon_template": "{{ 'mdi:pirate' }}",
+                            "attribute_templates": {
+                                "plus_one": "{{ trigger.event.data.beer + 1 }}"
+                            },
+                        }
+                    },
+                },
+            ],
+        },
+    )
+
+    await hass.async_block_till_done()
+
+    state = hass.states.get("sensor.hello")
+    assert state is not None
+    assert state.state == STATE_UNKNOWN
+
+    context = Context()
+    hass.bus.async_fire("test_event", {"beer": 2}, context=context)
+    await hass.async_block_till_done()
+
+    state = hass.states.get("sensor.hello")
+    assert state.state == "2"
+    assert state.attributes.get("device_class") == "battery"
+    assert state.attributes.get("icon") == "mdi:pirate"
+    assert state.attributes.get("entity_picture") == "/local/dogs.png"
+    assert state.attributes.get("plus_one") == 3
+    assert state.attributes.get("unit_of_measurement") == "%"
+    assert state.context is context
+
+    ent_reg = entity_registry.async_get(hass)
+    assert len(ent_reg.entities) == 1
+    assert (
+        ent_reg.entities["sensor.hello"].unique_id == "listening-test-event-just_a_test"
+    )
+
+
+async def test_trigger_entity_render_error(hass):
+    """Test trigger entity handles render error."""
+    assert await async_setup_component(
+        hass,
+        "template",
+        {
+            "template": {
+                "trigger": {"platform": "event", "event_type": "test_event"},
+                "sensors": {
+                    "hello": {
+                        "unique_id": "no-base-id",
+                        "friendly_name": "Hello",
+                        "value_template": "{{ non_existing + 1 }}",
+                    }
+                },
+            },
+        },
+    )
+
+    await hass.async_block_till_done()
+
+    state = hass.states.get("sensor.hello")
+    assert state is not None
+    assert state.state == STATE_UNKNOWN
+
+    context = Context()
+    hass.bus.async_fire("test_event", {"beer": 2}, context=context)
+    await hass.async_block_till_done()
+
+    state = hass.states.get("sensor.hello")
+    assert state.state == STATE_UNAVAILABLE
+
+    ent_reg = entity_registry.async_get(hass)
+    assert len(ent_reg.entities) == 1
+    assert ent_reg.entities["sensor.hello"].unique_id == "no-base-id"
+
+
+async def test_trigger_not_allowed_platform_config(hass, caplog):
+    """Test we throw a helpful warning if a trigger is configured in platform config."""
+    assert await async_setup_component(
+        hass,
+        sensor.DOMAIN,
+        {
+            "sensor": {
+                "platform": "template",
+                "trigger": {"platform": "event", "event_type": "test_event"},
+                "sensors": {
+                    "test_template_sensor": {
+                        "value_template": "{{ states.sensor.test_state.state }}",
+                        "friendly_name_template": "{{ states.sensor.test_state.state }}",
+                    }
+                },
+            }
+        },
+    )
+
+    await hass.async_block_till_done()
+
+    state = hass.states.get("sensor.test_template_sensor")
+    assert state is None
+    assert (
+        "You can only add triggers to template entities if they are defined under `template:`."
+        in caplog.text
+    )