Make result wrappers more robust (#42488)

homeassistant/helpers/template.py

@@ -127,7 +127,7 @@ def is_template_string(maybe_template: str) -> bool:
 class ResultWrapper:
     """Result wrapper class to store render result."""
 
-    render_result: str
+    render_result: Optional[str]
 
 
 def gen_result_wrapper(kls):
@@ -136,8 +136,8 @@ def gen_result_wrapper(kls):
     class Wrapper(kls, ResultWrapper):
         """Wrapper of a kls that can store render_result."""
 
-        def __init__(self, value: kls, render_result: str) -> None:
-            super().__init__(value)
+        def __init__(self, *args: tuple, render_result: Optional[str] = None) -> None:
+            super().__init__(*args)
             self.render_result = render_result
 
     return Wrapper
@@ -148,13 +148,15 @@ class TupleWrapper(tuple, ResultWrapper):
 
     # This is all magic to be allowed to subclass a tuple.
 
-    def __new__(cls, value: tuple, render_result: str) -> "TupleWrapper":
+    def __new__(
+        cls, value: tuple, *, render_result: Optional[str] = None
+    ) -> "TupleWrapper":
         """Create a new tuple class."""
         return super().__new__(cls, tuple(value))
 
     # pylint: disable=super-init-not-called
 
-    def __init__(self, value: tuple, render_result: str):
+    def __init__(self, value: tuple, *, render_result: Optional[str] = None):
         """Initialize a new tuple class."""
         self.render_result = render_result
 
@@ -416,7 +418,9 @@ class Template:
             result = literal_eval(render_result)
 
             if type(result) in RESULT_WRAPPERS:
-                result = RESULT_WRAPPERS[type(result)](result, render_result)
+                result = RESULT_WRAPPERS[type(result)](
+                    result, render_result=render_result
+                )
 
             # If the literal_eval result is a string, use the original
             # render, by not returning right here. The evaluation of strings

tests/helpers/test_template.py

@@ -5,6 +5,7 @@ import random
 
 import pytest
 import pytz
+import voluptuous as vol
 
 from homeassistant.components import group
 from homeassistant.config import async_process_ha_core_config
@@ -2684,14 +2685,16 @@ async def test_is_static_still_ast_evals(hass):
 
 async def test_result_wrappers(hass):
     """Test result wrappers."""
-    for text, native in (
-        ("[1, 2]", [1, 2]),
-        ("{1, 2}", {1, 2}),
-        ("(1, 2)", (1, 2)),
-        ('{"hello": True}', {"hello": True}),
+    for text, native, orig_type, schema in (
+        ("[1, 2]", [1, 2], list, vol.Schema([int])),
+        ("{1, 2}", {1, 2}, set, vol.Schema({int})),
+        ("(1, 2)", (1, 2), tuple, vol.ExactSequence([int, int])),
+        ('{"hello": True}', {"hello": True}, dict, vol.Schema({"hello": bool})),
     ):
         tpl = template.Template(text, hass)
         result = tpl.async_render()
+        assert isinstance(result, orig_type)
         assert isinstance(result, template.ResultWrapper)
         assert result == native
         assert result.render_result == text
+        schema(result)  # should not raise