Add WS command sensor/device_class_convertible_units (#85213)

* Add WS command sensor/device_class_units

* Rename new command to device_class_convertible_units

homeassistant/components/sensor/__init__.py

@@ -77,6 +77,7 @@ from .const import (  # noqa: F401
     SensorDeviceClass,
     SensorStateClass,
 )
+from .websocket_api import async_setup as async_setup_ws_api
 
 _LOGGER: Final = logging.getLogger(__name__)
 
@@ -109,6 +110,7 @@ async def async_setup(hass: HomeAssistant, config: ConfigType) -> bool:
         _LOGGER, DOMAIN, hass, SCAN_INTERVAL
     )
 
+    async_setup_ws_api(hass)
     await component.async_setup(config)
     return True
 

homeassistant/components/sensor/websocket_api.py

@@ -0,0 +1,35 @@
+"""The sensor websocket API."""
+from __future__ import annotations
+
+from typing import Any
+
+import voluptuous as vol
+
+from homeassistant.components import websocket_api
+from homeassistant.core import HomeAssistant, callback
+
+from .const import DEVICE_CLASS_UNITS, UNIT_CONVERTERS
+
+
+@callback
+def async_setup(hass: HomeAssistant) -> None:
+    """Set up the sensor websocket API."""
+    websocket_api.async_register_command(hass, ws_device_class_units)
+
+
+@callback
+@websocket_api.websocket_command(
+    {
+        vol.Required("type"): "sensor/device_class_convertible_units",
+        vol.Required("device_class"): str,
+    }
+)
+def ws_device_class_units(
+    hass: HomeAssistant, connection: websocket_api.ActiveConnection, msg: dict[str, Any]
+) -> None:
+    """Return supported units for a device class."""
+    device_class = msg["device_class"]
+    convertible_units = set()
+    if device_class in UNIT_CONVERTERS and device_class in DEVICE_CLASS_UNITS:
+        convertible_units = DEVICE_CLASS_UNITS[device_class]
+    connection.send_result(msg["id"], {"units": convertible_units})

tests/components/sensor/test_websocket_api.py

@@ -0,0 +1,53 @@
+"""Test the sensor websocket API."""
+from pytest_unordered import unordered
+
+from homeassistant.components.sensor.const import DOMAIN
+from homeassistant.core import HomeAssistant
+from homeassistant.setup import async_setup_component
+
+
+async def test_device_class_units(hass: HomeAssistant, hass_ws_client) -> None:
+    """Test we can get supported units."""
+    assert await async_setup_component(hass, DOMAIN, {})
+
+    client = await hass_ws_client(hass)
+
+    # Device class with units which sensor allows customizing & converting
+    await client.send_json(
+        {
+            "id": 1,
+            "type": "sensor/device_class_convertible_units",
+            "device_class": "speed",
+        }
+    )
+    msg = await client.receive_json()
+    assert msg["success"]
+    assert msg["result"] == {
+        "units": unordered(
+            ["km/h", "kn", "mph", "in/h", "in/d", "ft/s", "mm/d", "mm/h", "m/s"]
+        )
+    }
+
+    # Device class with units which sensor doesn't allow customizing & converting
+    await client.send_json(
+        {
+            "id": 2,
+            "type": "sensor/device_class_convertible_units",
+            "device_class": "energy",
+        }
+    )
+    msg = await client.receive_json()
+    assert msg["success"]
+    assert msg["result"] == {"units": []}
+
+    # Unknown device class
+    await client.send_json(
+        {
+            "id": 3,
+            "type": "sensor/device_class_convertible_units",
+            "device_class": "kebabsås",
+        }
+    )
+    msg = await client.receive_json()
+    assert msg["success"]
+    assert msg["result"] == {"units": unordered([])}