batch33 task5 port wave T1 mapped tests

dotnet/tests/ZB.MOM.NatsNet.Server.Tests/ImplBacklog/JetStreamClusterTests3.Impltests.cs

@@ -84,4 +84,29 @@ public sealed class JetStreamClusterTests3
         var engine = new JetStreamEngine(state);
         engine.SubjectsOverlap("A", ["orders.created"]).ShouldBeTrue();
     }
+
+    [Fact] // T:1118
+    public void JetStreamClusterStreamRescaleCatchup_ShouldSucceed()
+    {
+        var cluster = new JetStreamCluster
+        {
+            Streams = new Dictionary<string, Dictionary<string, StreamAssignment>>
+            {
+                ["A"] = new Dictionary<string, StreamAssignment>
+                {
+                    ["ORDERS"] = new()
+                    {
+                        Client = new ClientInfo { Account = "A" },
+                        Config = new StreamConfig { Name = "ORDERS", Replicas = 3 },
+                        Group = new RaftGroup { Name = "RG-ORDERS", Peers = ["S1", "S2"] },
+                    },
+                },
+            },
+        };
+        var state = new global::ZB.MOM.NatsNet.Server.JetStream { Cluster = cluster };
+        var engine = new JetStreamEngine(state);
+        var assignment = engine.StreamAssignment("A", "ORDERS");
+        assignment.ShouldNotBeNull();
+        assignment!.MissingPeers().ShouldBeTrue();
+    }
 }