Improve JSON errors from HTTP view (#87042)

homeassistant/components/http/view.py

@@ -20,7 +20,11 @@ import voluptuous as vol
 from homeassistant import exceptions
 from homeassistant.const import CONTENT_TYPE_JSON
 from homeassistant.core import Context, is_callback
-from homeassistant.helpers.json import JSON_ENCODE_EXCEPTIONS, json_bytes
+from homeassistant.helpers.json import JSON_ENCODE_EXCEPTIONS, json_bytes, json_dumps
+from homeassistant.util.json import (
+    find_paths_unserializable_data,
+    format_unserializable_data,
+)
 
 from .const import KEY_AUTHENTICATED, KEY_HASS
 
@@ -54,7 +58,12 @@ class HomeAssistantView:
         try:
             msg = json_bytes(result)
         except JSON_ENCODE_EXCEPTIONS as err:
-            _LOGGER.error("Unable to serialize to JSON: %s\n%s", err, result)
+            _LOGGER.error(
+                "Unable to serialize to JSON. Bad data found at %s",
+                format_unserializable_data(
+                    find_paths_unserializable_data(result, dump=json_dumps)
+                ),
+            )
             raise HTTPInternalServerError from err
         response = web.Response(
             body=msg,

tests/components/http/test_view.py

@@ -1,4 +1,5 @@
 """Tests for Home Assistant View."""
+from decimal import Decimal
 from http import HTTPStatus
 import json
 from unittest.mock import AsyncMock, Mock
@@ -32,18 +33,18 @@ def mock_request_with_stopping():
 
 async def test_invalid_json(caplog):
     """Test trying to return invalid JSON."""
-    view = HomeAssistantView()
-
     with pytest.raises(HTTPInternalServerError):
-        view.json(rb"\ud800")
+        HomeAssistantView.json({"hello": Decimal("2.0")})
 
-    assert "Unable to serialize to JSON" in caplog.text
+    assert (
+        "Unable to serialize to JSON. Bad data found at $.hello=2.0(<class 'decimal.Decimal'>"
+        in caplog.text
+    )
 
 
-async def test_nan_serialized_to_null(caplog):
+async def test_nan_serialized_to_null():
     """Test nan serialized to null JSON."""
-    view = HomeAssistantView()
-    response = view.json(float("NaN"))
+    response = HomeAssistantView.json(float("NaN"))
     assert json.loads(response.body.decode("utf-8")) is None