Populate trigger variable when manually triggering automation (#48202)

* Populate trigger variable when manually triggering automation

* Update tests/components/automation/test_init.py

Co-authored-by: Erik Montnemery <erik@montnemery.com>

homeassistant/components/automation/__init__.py

@@ -189,7 +189,7 @@ async def async_setup(hass, config):
     async def trigger_service_handler(entity, service_call):
         """Handle forced automation trigger, e.g. from frontend."""
         await entity.async_trigger(
-            service_call.data[ATTR_VARIABLES],
+            {**service_call.data[ATTR_VARIABLES], "trigger": {"platform": None}},
             skip_condition=service_call.data[CONF_SKIP_CONDITION],
             context=service_call.context,
         )

tests/components/automation/test_init.py

@@ -1355,3 +1355,33 @@ async def test_blueprint_automation(hass, calls):
     assert automation.entities_in_automation(hass, "automation.automation_0") == [
         "light.kitchen"
     ]
+
+
+async def test_trigger_service(hass, calls):
+    """Test the automation trigger service."""
+    assert await async_setup_component(
+        hass,
+        automation.DOMAIN,
+        {
+            automation.DOMAIN: {
+                "alias": "hello",
+                "trigger": {"platform": "event", "event_type": "test_event"},
+                "action": {
+                    "service": "test.automation",
+                    "data_template": {"trigger": "{{ trigger }}"},
+                },
+            }
+        },
+    )
+    context = Context()
+    await hass.services.async_call(
+        "automation",
+        "trigger",
+        {"entity_id": "automation.hello"},
+        blocking=True,
+        context=context,
+    )
+
+    assert len(calls) == 1
+    assert calls[0].data.get("trigger") == {"platform": None}
+    assert calls[0].context.parent_id is context.id