Move icon constants to entity attributes (#90518)

* Move icon constants to attribute

* Adjust test

homeassistant/components/fixer/sensor.py

@@ -19,12 +19,10 @@ _LOGGER = logging.getLogger(__name__)
 
 ATTR_EXCHANGE_RATE = "Exchange rate"
 ATTR_TARGET = "Target currency"
-ATTRIBUTION = "Data provided by the European Central Bank (ECB)"
 
 DEFAULT_BASE = "USD"
 DEFAULT_NAME = "Exchange rate"
 
-ICON = "mdi:currency-usd"
 
 SCAN_INTERVAL = timedelta(days=1)
 
@@ -61,7 +59,8 @@ def setup_platform(
 class ExchangeRateSensor(SensorEntity):
     """Representation of a Exchange sensor."""
 
-    _attr_attribution = ATTRIBUTION
+    _attr_attribution = "Data provided by the European Central Bank (ECB)"
+    _attr_icon = "mdi:currency-usd"
 
     def __init__(self, data, name, target):
         """Initialize the sensor."""
@@ -94,11 +93,6 @@ class ExchangeRateSensor(SensorEntity):
                 ATTR_TARGET: self._target,
             }
 
-    @property
-    def icon(self):
-        """Return the icon to use in the frontend, if any."""
-        return ICON
-
     def update(self) -> None:
         """Get the latest data and updates the states."""
         self.data.update()