Ensure all template errors are caught and the websocket api reports them (#41719)

homeassistant/components/websocket_api/commands.py

@@ -257,13 +257,20 @@ async def handle_render_template(hass, connection, msg):
     timeout = msg.get("timeout")
     info = None
 
-    if timeout and await template.async_render_will_timeout(timeout):
-        connection.send_error(
-            msg["id"],
-            const.ERR_TEMPLATE_ERROR,
-            f"Exceeded maximum execution time of {timeout}s",
-        )
-        return
+    if timeout:
+        try:
+            timed_out = await template.async_render_will_timeout(timeout)
+        except TemplateError as ex:
+            connection.send_error(msg["id"], const.ERR_TEMPLATE_ERROR, str(ex))
+            return
+
+        if timed_out:
+            connection.send_error(
+                msg["id"],
+                const.ERR_TEMPLATE_ERROR,
+                f"Exceeded maximum execution time of {timeout}s",
+            )
+            return
 
     @callback
     def _template_listener(event, updates):

homeassistant/exceptions.py

@@ -1,8 +1,6 @@
 """The exceptions used by Home Assistant."""
 from typing import TYPE_CHECKING, Optional
 
-import jinja2
-
 if TYPE_CHECKING:
     from .core import Context  # noqa: F401 pylint: disable=unused-import
 
@@ -22,7 +20,7 @@ class NoEntitySpecifiedError(HomeAssistantError):
 class TemplateError(HomeAssistantError):
     """Error during template rendering."""
 
-    def __init__(self, exception: jinja2.TemplateError) -> None:
+    def __init__(self, exception: Exception) -> None:
         """Init the error."""
         super().__init__(f"{exception.__class__.__name__}: {exception}")
 

homeassistant/helpers/template.py

@@ -331,7 +331,7 @@ class Template:
 
         try:
             render_result = compiled.render(kwargs)
-        except jinja2.TemplateError as err:
+        except Exception as err:  # pylint: disable=broad-except
             raise TemplateError(err) from err
 
         render_result = render_result.strip()

tests/components/websocket_api/test_commands.py

@@ -485,6 +485,41 @@ async def test_render_template_with_error(hass, websocket_client, caplog):
     assert "TemplateError" not in caplog.text
 
 
+async def test_render_template_with_timeout_and_error(hass, websocket_client, caplog):
+    """Test a template with an error with a timeout."""
+    await websocket_client.send_json(
+        {
+            "id": 5,
+            "type": "render_template",
+            "template": "{{ now() | rando }}",
+            "timeout": 5,
+        }
+    )
+
+    msg = await websocket_client.receive_json()
+    assert msg["id"] == 5
+    assert msg["type"] == const.TYPE_RESULT
+    assert not msg["success"]
+    assert msg["error"]["code"] == const.ERR_TEMPLATE_ERROR
+
+    assert "TemplateError" not in caplog.text
+
+
+async def test_render_template_error_in_template_code(hass, websocket_client, caplog):
+    """Test a template that will throw in template.py."""
+    await websocket_client.send_json(
+        {"id": 5, "type": "render_template", "template": "{{ now() | random }}"}
+    )
+
+    msg = await websocket_client.receive_json()
+    assert msg["id"] == 5
+    assert msg["type"] == const.TYPE_RESULT
+    assert not msg["success"]
+    assert msg["error"]["code"] == const.ERR_TEMPLATE_ERROR
+
+    assert "TemplateError" not in caplog.text
+
+
 async def test_render_template_with_delayed_error(hass, websocket_client, caplog):
     """Test a template with an error that only happens after a state change."""
     hass.states.async_set("sensor.test", "on")

tests/helpers/test_template.py

@@ -2533,6 +2533,16 @@ async def test_lights(hass):
         assert f"sensor{i}" in info.result()
 
 
+async def test_template_errors(hass):
+    """Test template rendering wraps exceptions with TemplateError."""
+
+    with pytest.raises(TemplateError):
+        template.Template("{{ now() | rando }}", hass).async_render()
+
+    with pytest.raises(TemplateError):
+        template.Template("{{ now() | random }}", hass).async_render()
+
+
 async def test_state_attributes(hass):
     """Test state attributes."""
     hass.states.async_set("sensor.test", "23")