Add buttons to Blue current integration (#143964)

* Add buttons to Blue current integration

* Apply feedback

* Changed configEntry to use the BlueCurrentConfigEntry.

The connector is now accessed via the entry instead of hass.data.

* Changed test_buttons_created test to use the snapshot_platform function.

Also removed the entry.unique_id check in the test_charge_point_buttons function because this is not needed anymore, according to https://github.com/home-assistant/core/pull/114000#discussion_r1627201872

* Applied requested changes.

Changes requested by joostlek.

* Moved has_value from BlueCurrentEntity to class level.

This value was still inside the __init__ function, so the value was not overwritten by the ChargePointButton.

---------

Co-authored-by: Floris272 <florispuijk@outlook.com>

homeassistant/components/blue_current/entity.py

@@ -1,7 +1,5 @@
 """Entity representing a Blue Current charge point."""
 
-from abc import abstractmethod
-
 from homeassistant.const import ATTR_NAME
 from homeassistant.core import callback
 from homeassistant.helpers.device_registry import DeviceInfo
@@ -17,12 +15,12 @@ class BlueCurrentEntity(Entity):
 
     _attr_has_entity_name = True
     _attr_should_poll = False
+    has_value = False
 
     def __init__(self, connector: Connector, signal: str) -> None:
         """Initialize the entity."""
         self.connector = connector
         self.signal = signal
-        self.has_value = False
 
     async def async_added_to_hass(self) -> None:
         """Register callbacks."""
@@ -43,7 +41,6 @@ class BlueCurrentEntity(Entity):
         return self.connector.connected and self.has_value
 
     @callback
-    @abstractmethod
     def update_from_latest_data(self) -> None:
         """Update the entity from the latest data."""