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/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})