Restore unnecessary assignment of Template.hass in event helper (#125143)

homeassistant/helpers/event.py

@@ -981,6 +981,22 @@ class TrackTemplateResultInfo:
 
         self._last_result: dict[Template, bool | str | TemplateError] = {}
 
+        for track_template_ in track_templates:
+            if track_template_.template.hass:
+                continue
+
+            # pylint: disable-next=import-outside-toplevel
+            from .frame import report
+
+            report(
+                (
+                    "calls async_track_template_result with template without hass, "
+                    "which will stop working in HA Core 2025.10"
+                ),
+                error_if_core=False,
+            )
+            track_template_.template.hass = hass
+
         self._rate_limit = KeyedRateLimit(hass)
         self._info: dict[Template, RenderInfo] = {}
         self._track_state_changes: _TrackStateChangeFiltered | None = None

tests/helpers/test_event.py

@@ -4938,3 +4938,43 @@ async def test_async_track_state_report_event(hass: HomeAssistant) -> None:
     await hass.async_block_till_done()
     assert len(tracker_called) == 2
     unsub()
+
+
+async def test_async_track_template_no_hass_deprecated(
+    hass: HomeAssistant, caplog: pytest.LogCaptureFixture
+) -> None:
+    """Test async_track_template with a template without hass is deprecated."""
+    message = (
+        "Detected code that calls async_track_template_result with template without "
+        "hass, which will stop working in HA Core 2025.10. Please report this issue."
+    )
+
+    async_track_template(hass, Template("blah"), lambda x, y, z: None)
+    assert message in caplog.text
+    caplog.clear()
+
+    async_track_template(hass, Template("blah", hass), lambda x, y, z: None)
+    assert message not in caplog.text
+    caplog.clear()
+
+
+async def test_async_track_template_result_no_hass_deprecated(
+    hass: HomeAssistant, caplog: pytest.LogCaptureFixture
+) -> None:
+    """Test async_track_template_result with a template without hass is deprecated."""
+    message = (
+        "Detected code that calls async_track_template_result with template without "
+        "hass, which will stop working in HA Core 2025.10. Please report this issue."
+    )
+
+    async_track_template_result(
+        hass, [TrackTemplate(Template("blah"), None)], lambda x, y, z: None
+    )
+    assert message in caplog.text
+    caplog.clear()
+
+    async_track_template_result(
+        hass, [TrackTemplate(Template("blah", hass), None)], lambda x, y, z: None
+    )
+    assert message not in caplog.text
+    caplog.clear()