Hide unconnected breakers from component graph

RELEASE_NOTES.md

@@ -10,7 +10,7 @@
 
 ## New Features
 
-<!-- Here goes the main new features and examples or instructions on how to use them -->
+- If there are unconnected breakers at a site, they are now hidden from the component graph.  If there are breakers with connections to other components, they are still sent to the component graph.  This is a temporary measure until the graph traversal supports breakers.
 
 ## Bug Fixes
 

src/frequenz/gridpool/_graph_generator.py

@@ -3,15 +3,20 @@
 
 """Formula generation from assets API component/connection configurations."""
 
+import logging
+
 from frequenz.client.assets import AssetsApiClient
 from frequenz.client.assets.electrical_component import (
+    Breaker,
     ComponentConnection,
     ElectricalComponent,
 )
 from frequenz.client.common.microgrid import MicrogridId
 from frequenz.client.common.microgrid.electrical_components import ElectricalComponentId
 from frequenz.microgrid_component_graph import ComponentGraph
 
+_logger = logging.getLogger(__name__)
+
 
 class ComponentGraphGenerator:
     """Generates component graphs for microgrids using the Assets API."""
@@ -57,6 +62,26 @@ async def get_component_graph(
         if any(c is None for c in connections):
             raise ValueError("Failed to load all electrical component connections.")
 
+        breakers = [c for c in components if isinstance(c, Breaker)]
+        connected_breakers = [
+            b
+            for b in breakers
+            if any(
+                b.id in (c.source, c.destination) for c in connections if c is not None
+            )
+        ]
+
+        if connected_breakers:
+            _logger.warning(
+                "The following breakers are connected to other components, "
+                + "which is not supported by the component graph generator and may "
+                + "lead to graph traversal issues: %s",
+                [b.id for b in connected_breakers],
+            )
+        elif breakers:
+            _logger.debug("Dropping unconnected breakers: %s", [b.id for b in breakers])
+            components = [c for c in components if not isinstance(c, Breaker)]
+
         graph = ComponentGraph[
             ElectricalComponent, ComponentConnection, ElectricalComponentId
         ](components, connections)