Add enum util (#87082)

* Add enum helper

* docstring

* Move to util

* Add use case

homeassistant/components/sensor/__init__.py

@@ -3,7 +3,6 @@ from __future__ import annotations
 
 import asyncio
 from collections.abc import Mapping
-from contextlib import suppress
 from dataclasses import dataclass
 from datetime import date, datetime, timedelta, timezone
 from decimal import Decimal, InvalidOperation as DecimalInvalidOperation
@@ -59,6 +58,7 @@ from homeassistant.helpers.entity_platform import EntityPlatform
 from homeassistant.helpers.restore_state import ExtraStoredData, RestoreEntity
 from homeassistant.helpers.typing import UNDEFINED, ConfigType, StateType, UndefinedType
 from homeassistant.util import dt as dt_util
+from homeassistant.util.enum import try_parse_enum
 
 from .const import (  # noqa: F401
     ATTR_LAST_RESET,
@@ -464,11 +464,9 @@ class SensorEntity(Entity):
         native_unit_of_measurement = self.native_unit_of_measurement
         unit_of_measurement = self.unit_of_measurement
         value = self.native_value
-        device_class: SensorDeviceClass | None = None
-        with suppress(ValueError):
-            # For the sake of validation, we can ignore custom device classes
-            # (customization and legacy style translations)
-            device_class = SensorDeviceClass(str(self.device_class))
+        # For the sake of validation, we can ignore custom device classes
+        # (customization and legacy style translations)
+        device_class = try_parse_enum(SensorDeviceClass, self.device_class)
         state_class = self.state_class
 
         # Sensors with device classes indicating a non-numeric value

homeassistant/util/enum.py

@@ -0,0 +1,16 @@
+"""Helpers for working with enums."""
+import contextlib
+from enum import Enum
+from typing import Any, TypeVar
+
+_EnumT = TypeVar("_EnumT", bound=Enum)
+
+
+def try_parse_enum(cls: type[_EnumT], value: Any) -> _EnumT | None:
+    """Try to parse the value into an Enum.
+
+    Return None if parsing fails.
+    """
+    with contextlib.suppress(ValueError):
+        return cls(value)
+    return None

tests/util/test_enum.py

@@ -0,0 +1,51 @@
+"""Test enum helpers."""
+from enum import Enum, IntEnum, IntFlag
+from typing import Any
+
+import pytest
+
+from homeassistant.backports.enum import StrEnum
+from homeassistant.util.enum import try_parse_enum
+
+
+class _AStrEnum(StrEnum):
+    VALUE = "value"
+
+
+class _AnIntEnum(IntEnum):
+    VALUE = 1
+
+
+class _AnIntFlag(IntFlag):
+    VALUE = 1
+
+
+@pytest.mark.parametrize(
+    "enum_type,value,expected",
+    [
+        # StrEnum valid checks
+        (_AStrEnum, _AStrEnum.VALUE, _AStrEnum.VALUE),
+        (_AStrEnum, "value", _AStrEnum.VALUE),
+        # StrEnum invalid checks
+        (_AStrEnum, "invalid", None),
+        (_AStrEnum, 1, None),
+        (_AStrEnum, None, None),
+        # IntEnum valid checks
+        (_AnIntEnum, _AnIntEnum.VALUE, _AnIntEnum.VALUE),
+        (_AnIntEnum, 1, _AnIntEnum.VALUE),
+        # IntEnum invalid checks
+        (_AnIntEnum, "value", None),
+        (_AnIntEnum, 2, None),
+        (_AnIntEnum, None, None),
+        # IntFlag valid checks
+        (_AnIntFlag, _AnIntFlag.VALUE, _AnIntFlag.VALUE),
+        (_AnIntFlag, 1, _AnIntFlag.VALUE),
+        (_AnIntFlag, 2, _AnIntFlag(2)),
+        # IntFlag invalid checks
+        (_AnIntFlag, "value", None),
+        (_AnIntFlag, None, None),
+    ],
+)
+def test_try_parse(enum_type: type[Enum], value: Any, expected: Enum | None) -> None:
+    """Test parsing of values into an Enum."""
+    assert try_parse_enum(enum_type, value) is expected