Deprecate CONF_UNIT_SYSTEM_*** constants (#80320)

* Deprecate CONF_UNIT_SYSTEM_*** constants

* Adjust pylint plugin

* Add tests

* Remove single-use function

* Revert logic change

* Revert "Revert logic change"

This reverts commit 60959a0050.

* Tweak again

homeassistant/components/config/core.py

@@ -5,10 +5,9 @@ import voluptuous as vol
 from homeassistant.components import websocket_api
 from homeassistant.components.http import HomeAssistantView
 from homeassistant.config import async_check_ha_config_file
-from homeassistant.const import CONF_UNIT_SYSTEM_IMPERIAL, CONF_UNIT_SYSTEM_METRIC
 from homeassistant.helpers import config_validation as cv
 from homeassistant.helpers.aiohttp_client import async_get_clientsession
-from homeassistant.util import location
+from homeassistant.util import location, unit_system
 
 
 async def async_setup(hass):
@@ -41,7 +40,7 @@ class CheckConfigView(HomeAssistantView):
         vol.Optional("latitude"): cv.latitude,
         vol.Optional("longitude"): cv.longitude,
         vol.Optional("elevation"): int,
-        vol.Optional("unit_system"): cv.unit_system,
+        vol.Optional("unit_system"): unit_system.validate_unit_system,
         vol.Optional("location_name"): str,
         vol.Optional("time_zone"): cv.time_zone,
         vol.Optional("external_url"): vol.Any(cv.url_no_path, None),
@@ -77,10 +76,14 @@ async def websocket_detect_config(hass, connection, msg):
         connection.send_result(msg["id"], info)
         return
 
+    # We don't want any integrations to use the name of the unit system
+    # so we are using the private attribute here
     if location_info.use_metric:
-        info["unit_system"] = CONF_UNIT_SYSTEM_METRIC
+        # pylint: disable-next=protected-access
+        info["unit_system"] = unit_system._CONF_UNIT_SYSTEM_METRIC
     else:
-        info["unit_system"] = CONF_UNIT_SYSTEM_IMPERIAL
+        # pylint: disable-next=protected-access
+        info["unit_system"] = unit_system._CONF_UNIT_SYSTEM_IMPERIAL
 
     if location_info.latitude:
         info["latitude"] = location_info.latitude

homeassistant/config.py

@@ -44,7 +44,6 @@ from .const import (
     CONF_TIME_ZONE,
     CONF_TYPE,
     CONF_UNIT_SYSTEM,
-    CONF_UNIT_SYSTEM_IMPERIAL,
     LEGACY_CONF_WHITELIST_EXTERNAL_DIRS,
     __version__,
 )
@@ -60,7 +59,7 @@ from .helpers.typing import ConfigType
 from .loader import Integration, IntegrationNotFound
 from .requirements import RequirementsNotFound, async_get_integration_with_requirements
 from .util.package import is_docker_env
-from .util.unit_system import IMPERIAL_SYSTEM, METRIC_SYSTEM
+from .util.unit_system import get_unit_system, validate_unit_system
 from .util.yaml import SECRET_YAML, Secrets, load_yaml
 
 _LOGGER = logging.getLogger(__name__)
@@ -204,7 +203,7 @@ CORE_CONFIG_SCHEMA = vol.All(
             CONF_LONGITUDE: cv.longitude,
             CONF_ELEVATION: vol.Coerce(int),
             vol.Remove(CONF_TEMPERATURE_UNIT): cv.temperature_unit,
-            CONF_UNIT_SYSTEM: cv.unit_system,
+            CONF_UNIT_SYSTEM: validate_unit_system,
             CONF_TIME_ZONE: cv.time_zone,
             vol.Optional(CONF_INTERNAL_URL): cv.url,
             vol.Optional(CONF_EXTERNAL_URL): cv.url,
@@ -602,10 +601,7 @@ async def async_process_ha_core_config(hass: HomeAssistant, config: dict) -> Non
     hass.data[DATA_CUSTOMIZE] = EntityValues(cust_exact, cust_domain, cust_glob)
 
     if CONF_UNIT_SYSTEM in config:
-        if config[CONF_UNIT_SYSTEM] == CONF_UNIT_SYSTEM_IMPERIAL:
-            hac.units = IMPERIAL_SYSTEM
-        else:
-            hac.units = METRIC_SYSTEM
+        hac.units = get_unit_system(config[CONF_UNIT_SYSTEM])
 
 
 def _log_pkg_error(package: str, component: str, config: dict, message: str) -> None:

homeassistant/const.py

@@ -396,7 +396,9 @@ ATTR_ICON: Final = "icon"
 ATTR_UNIT_OF_MEASUREMENT: Final = "unit_of_measurement"
 
 CONF_UNIT_SYSTEM_METRIC: Final = "metric"
+"""Deprecated: please use a local constant."""
 CONF_UNIT_SYSTEM_IMPERIAL: Final = "imperial"
+"""Deprecated: please use a local constant."""
 
 # Electrical attributes
 ATTR_VOLTAGE: Final = "voltage"

homeassistant/core.py

@@ -49,7 +49,6 @@ from .const import (
     ATTR_FRIENDLY_NAME,
     ATTR_SERVICE,
     ATTR_SERVICE_DATA,
-    CONF_UNIT_SYSTEM_IMPERIAL,
     EVENT_CALL_SERVICE,
     EVENT_CORE_CONFIG_UPDATE,
     EVENT_HOMEASSISTANT_CLOSE,
@@ -82,7 +81,7 @@ from .util.async_ import (
 )
 from .util.read_only_dict import ReadOnlyDict
 from .util.timeout import TimeoutManager
-from .util.unit_system import IMPERIAL_SYSTEM, METRIC_SYSTEM, UnitSystem
+from .util.unit_system import METRIC_SYSTEM, UnitSystem, get_unit_system
 
 # Typing imports that create a circular dependency
 if TYPE_CHECKING:
@@ -1940,9 +1939,9 @@ class Config:
         if elevation is not None:
             self.elevation = elevation
         if unit_system is not None:
-            if unit_system == CONF_UNIT_SYSTEM_IMPERIAL:
-                self.units = IMPERIAL_SYSTEM
-            else:
+            try:
+                self.units = get_unit_system(unit_system)
+            except ValueError:
                 self.units = METRIC_SYSTEM
         if location_name is not None:
             self.location_name = location_name
@@ -2015,7 +2014,7 @@ class Config:
             "latitude": self.latitude,
             "longitude": self.longitude,
             "elevation": self.elevation,
-            # We don't want any components to use the name of the unit system
+            # We don't want any integrations to use the name of the unit system
             # so we are using the private attribute here
             "unit_system": self.units._name,  # pylint: disable=protected-access
             "location_name": self.location_name,

homeassistant/helpers/config_validation.py

@@ -71,8 +71,6 @@ from homeassistant.const import (
     CONF_TARGET,
     CONF_THEN,
     CONF_TIMEOUT,
-    CONF_UNIT_SYSTEM_IMPERIAL,
-    CONF_UNIT_SYSTEM_METRIC,
     CONF_UNTIL,
     CONF_VALUE_TEMPLATE,
     CONF_VARIABLES,
@@ -588,11 +586,6 @@ def temperature_unit(value: Any) -> str:
     raise vol.Invalid("invalid temperature unit (expected C or F)")
 
 
-unit_system = vol.All(
-    vol.Lower, vol.Any(CONF_UNIT_SYSTEM_METRIC, CONF_UNIT_SYSTEM_IMPERIAL)
-)
-
-
 def template(value: Any | None) -> template_helper.Template:
     """Validate a jinja2 template."""
     if value is None:

homeassistant/util/unit_system.py

@@ -2,11 +2,12 @@
 from __future__ import annotations
 
 from numbers import Number
+from typing import Final
+
+import voluptuous as vol
 
 from homeassistant.const import (
     ACCUMULATED_PRECIPITATION,
-    CONF_UNIT_SYSTEM_IMPERIAL,
-    CONF_UNIT_SYSTEM_METRIC,
     LENGTH,
     LENGTH_INCHES,
     LENGTH_KILOMETERS,
@@ -41,6 +42,9 @@ from .unit_conversion import (
     VolumeConverter,
 )
 
+_CONF_UNIT_SYSTEM_IMPERIAL: Final = "imperial"
+_CONF_UNIT_SYSTEM_METRIC: Final = "metric"
+
 LENGTH_UNITS = DistanceConverter.VALID_UNITS
 
 MASS_UNITS: set[str] = {MASS_POUNDS, MASS_OUNCES, MASS_KILOGRAMS, MASS_GRAMS}
@@ -207,8 +211,21 @@ class UnitSystem:
         }
 
 
+def get_unit_system(key: str) -> UnitSystem:
+    """Get unit system based on key."""
+    if key == _CONF_UNIT_SYSTEM_IMPERIAL:
+        return IMPERIAL_SYSTEM
+    if key == _CONF_UNIT_SYSTEM_METRIC:
+        return METRIC_SYSTEM
+    raise ValueError(f"`{key}` is not a valid unit system key")
+
+
+validate_unit_system = vol.All(
+    vol.Lower, vol.Any(_CONF_UNIT_SYSTEM_METRIC, _CONF_UNIT_SYSTEM_IMPERIAL)
+)
+
 METRIC_SYSTEM = UnitSystem(
-    CONF_UNIT_SYSTEM_METRIC,
+    _CONF_UNIT_SYSTEM_METRIC,
     TEMP_CELSIUS,
     LENGTH_KILOMETERS,
     SPEED_METERS_PER_SECOND,
@@ -219,7 +236,7 @@ METRIC_SYSTEM = UnitSystem(
 )
 
 IMPERIAL_SYSTEM = UnitSystem(
-    CONF_UNIT_SYSTEM_IMPERIAL,
+    _CONF_UNIT_SYSTEM_IMPERIAL,
     TEMP_FAHRENHEIT,
     LENGTH_MILES,
     SPEED_MILES_PER_HOUR,

pylint/plugins/hass_imports.py

@@ -267,6 +267,10 @@ _OBSOLETE_IMPORT: dict[str, list[ObsoleteImportMatch]] = {
             reason="replaced by EntityCategory enum",
             constant=re.compile(r"^(ENTITY_CATEGORY_(\w*))|(ENTITY_CATEGORIES)$"),
         ),
+        ObsoleteImportMatch(
+            reason="replaced by local constants",
+            constant=re.compile(r"^(CONF_UNIT_SYSTEM_(\w*))$"),
+        ),
     ],
     "homeassistant.core": [
         ObsoleteImportMatch(

tests/util/test_unit_system.py

@@ -3,8 +3,6 @@ import pytest
 
 from homeassistant.const import (
     ACCUMULATED_PRECIPITATION,
-    CONF_UNIT_SYSTEM_IMPERIAL,
-    CONF_UNIT_SYSTEM_METRIC,
     LENGTH,
     LENGTH_KILOMETERS,
     LENGTH_METERS,
@@ -21,7 +19,14 @@ from homeassistant.const import (
     WIND_SPEED,
 )
 from homeassistant.exceptions import HomeAssistantError
-from homeassistant.util.unit_system import IMPERIAL_SYSTEM, METRIC_SYSTEM, UnitSystem
+from homeassistant.util.unit_system import (
+    _CONF_UNIT_SYSTEM_IMPERIAL,
+    _CONF_UNIT_SYSTEM_METRIC,
+    IMPERIAL_SYSTEM,
+    METRIC_SYSTEM,
+    UnitSystem,
+    get_unit_system,
+)
 
 SYSTEM_NAME = "TEST"
 INVALID_UNIT = "INVALID"
@@ -317,8 +322,8 @@ def test_is_metric(
 @pytest.mark.parametrize(
     "unit_system, expected_name",
     [
-        (METRIC_SYSTEM, CONF_UNIT_SYSTEM_METRIC),
-        (IMPERIAL_SYSTEM, CONF_UNIT_SYSTEM_IMPERIAL),
+        (METRIC_SYSTEM, _CONF_UNIT_SYSTEM_METRIC),
+        (IMPERIAL_SYSTEM, _CONF_UNIT_SYSTEM_IMPERIAL),
     ],
 )
 def test_deprecated_name(
@@ -330,3 +335,22 @@ def test_deprecated_name(
         "Detected code that accesses the `name` property of the unit system."
         in caplog.text
     )
+
+
+@pytest.mark.parametrize(
+    "key, expected_system",
+    [
+        (_CONF_UNIT_SYSTEM_METRIC, METRIC_SYSTEM),
+        (_CONF_UNIT_SYSTEM_IMPERIAL, IMPERIAL_SYSTEM),
+    ],
+)
+def test_get_unit_system(key: str, expected_system: UnitSystem) -> None:
+    """Test get_unit_system."""
+    assert get_unit_system(key) is expected_system
+
+
+@pytest.mark.parametrize("key", [None, "", "invalid_custom"])
+def test_get_unit_system_invalid(key: str) -> None:
+    """Test get_unit_system with an invalid key."""
+    with pytest.raises(ValueError, match=f"`{key}` is not a valid unit system key"):
+        _ = get_unit_system(key)