fixup! Implement ListConnections

Add active_at().

Author: llucax

src/frequenz/client/microgrid/component/_connection.py

@@ -4,6 +4,7 @@
 """Component connection."""
 
 import dataclasses
+from datetime import datetime, timezone
 from functools import cached_property
 
 from .._id import ComponentId
@@ -58,10 +59,14 @@ def __post_init__(self) -> None:
         if self.source == self.destination:
             raise ValueError("Source and destination components must be different")
 
+    def active_at(self, timestamp: datetime) -> bool:
+        """Check whether this connection is active at a specific timestamp."""
+        return self.operational_lifetime.active_at(timestamp)
+
     @cached_property
     def active(self) -> bool:
         """Whether this connection is currently active."""
-        return self.operational_lifetime.active
+        return self.active_at(datetime.now(timezone.utc))
 
     def __str__(self) -> str:
         """Return a human-readable string representation of this instance."""