task6: implement batch38 group E state snapshot and wait queue

dotnet/tests/ZB.MOM.NatsNet.Server.Tests/JetStream/WaitQueueTests.cs

@@ -48,4 +48,39 @@ public sealed class WaitQueueTests
         q.Cycle();
         q.Peek()!.Reply.ShouldBe("1b");
     }
+
+    [Fact]
+    public void WaitingRequestRecycle_AndWaitQueueFactory_ShouldBehave()
+    {
+        var request = new WaitingRequest
+        {
+            Subject = "s",
+            Reply = "r",
+            N = 0,
+            D = 1,
+            MaxBytes = 10,
+            B = 10,
+            PriorityGroup = new PriorityGroup { Group = "g", Priority = 1 },
+        };
+
+        request.RecycleIfDone().ShouldBeTrue();
+        request.Subject.ShouldBe(string.Empty);
+        request.Reply.ShouldBeNull();
+
+        var q = WaitQueue.NewWaitQueue(max: 3);
+        q.ShouldNotBeNull();
+        q.IsFull(3).ShouldBeFalse();
+    }
+
+    [Fact]
+    public void WaitingDeliveryRecycle_ShouldClearState()
+    {
+        var wd = new WaitingDelivery { Reply = "r", Sequence = 42, Created = DateTime.UtcNow };
+
+        wd.Recycle();
+
+        wd.Reply.ShouldBe(string.Empty);
+        wd.Sequence.ShouldBe(0UL);
+        wd.Created.ShouldBe(DateTime.UnixEpoch);
+    }
 }