test(redundancy): cover absent-node default-historize for HistorianAdapter (A2)

tests/Server/ZB.MOM.WW.OtOpcUa.Runtime.Tests/Historian/HistorianAdapterActorTests.cs

@@ -135,4 +135,33 @@ public sealed class HistorianAdapterActorTests : RuntimeActorTestBase
 
         AwaitAssert(() => sink.EnqueueCount.ShouldBe(1), Settle);
     }
+
+    /// <summary>Absent-node default-historize (T5): a snapshot that mentions only a DIFFERENT node
+    /// must NOT update the local cached role — the actor's own node is absent, so the role stays
+    /// null/unknown and the default-historize path must fire. Partial/stale snapshots MUST NOT
+    /// silently suppress historization for nodes not yet observed.</summary>
+    [Fact]
+    public void Redundancy_snapshot_without_local_node_leaves_role_unknown_and_historizes()
+    {
+        var sink = new RecordingSink();
+        var actor = Sys.ActorOf(HistorianAdapterActor.Props(sink, LocalNode));
+
+        // Send a snapshot that only describes a peer node — the local node is absent.
+        actor.Tell(new RedundancyStateChanged(
+            new[]
+            {
+                new NodeRedundancyState(
+                    NodeId: new NodeId("some-other-node"),
+                    Role: RedundancyRole.Secondary,
+                    IsClusterLeader: false,
+                    IsRoleLeaderForDriver: false,
+                    AsOfUtc: DateTime.UtcNow),
+            },
+            CorrelationId.NewId()));
+
+        actor.Tell(SampleEvent());
+
+        // Local role is still unknown ⇒ default-historize path: sink must record exactly one enqueue.
+        AwaitAssert(() => sink.EnqueueCount.ShouldBe(1), Settle);
+    }
 }