Implement deferred core utility parity APIs/tests and refresh tracking artifacts

dotnet/tests/ZB.MOM.NatsNet.Server.Tests/Internal/AccessTimeServiceTests.cs

@@ -77,4 +77,16 @@ public sealed class AccessTimeServiceTests : IDisposable
         // Mirror: TestUnbalancedUnregister
         Should.Throw<InvalidOperationException>(() => AccessTimeService.Unregister());
     }
+
+    [Fact]
+    public void Init_ShouldBeIdempotentAndNonThrowing()
+    {
+        Should.NotThrow(() => AccessTimeService.Init());
+        var first = AccessTimeService.AccessTime();
+        first.ShouldBeGreaterThan(0);
+
+        Should.NotThrow(() => AccessTimeService.Init());
+        var second = AccessTimeService.AccessTime();
+        second.ShouldBeGreaterThan(0);
+    }
 }

dotnet/tests/ZB.MOM.NatsNet.Server.Tests/Internal/IpQueueTests.cs

@@ -28,6 +28,62 @@ namespace ZB.MOM.NatsNet.Server.Tests.Internal;
 /// </summary>
 public sealed class IpQueueTests
 {
+    [Fact]
+    public void IpqMaxRecycleSize_ShouldAffectQueueConfig()
+    {
+        var q = IpQueue<int>.NewIPQueue("opt-max-recycle", null, IpQueue<int>.IpqMaxRecycleSize(123));
+        q.MaxRecycleSize.ShouldBe(123);
+    }
+
+    [Fact]
+    public void IpqSizeCalculation_AndLimitBySize_ShouldEnforceLimit()
+    {
+        var q = IpQueue<byte[]>.NewIPQueue(
+            "opt-size-limit",
+            null,
+            IpQueue<byte[]>.IpqSizeCalculation(e => (ulong)e.Length),
+            IpQueue<byte[]>.IpqLimitBySize(8));
+
+        var (_, err1) = q.Push(new byte[4]);
+        err1.ShouldBeNull();
+
+        var (_, err2) = q.Push(new byte[4]);
+        err2.ShouldBeNull();
+
+        var (_, err3) = q.Push(new byte[1]);
+        err3.ShouldBeSameAs(IpQueueErrors.SizeLimitReached);
+    }
+
+    [Fact]
+    public void IpqLimitByLen_ShouldEnforceLengthLimit()
+    {
+        var q = IpQueue<int>.NewIPQueue("opt-len-limit", null, IpQueue<int>.IpqLimitByLen(2));
+
+        q.Push(1).error.ShouldBeNull();
+        q.Push(2).error.ShouldBeNull();
+        q.Push(3).error.ShouldBeSameAs(IpQueueErrors.LenLimitReached);
+    }
+
+    [Fact]
+    public void NewIPQueue_ShouldApplyOptionsAndRegister()
+    {
+        var registry = new ConcurrentDictionary<string, object>();
+        var q = IpQueue<int>.NewIPQueue(
+            "opt-factory",
+            registry,
+            IpQueue<int>.IpqMaxRecycleSize(55),
+            IpQueue<int>.IpqLimitByLen(1));
+
+        q.MaxRecycleSize.ShouldBe(55);
+        registry.TryGetValue("opt-factory", out var registered).ShouldBeTrue();
+        registered.ShouldBeSameAs(q);
+
+        var (_, err1) = q.Push(1);
+        err1.ShouldBeNull();
+        var (_, err2) = q.Push(2);
+        err2.ShouldBeSameAs(IpQueueErrors.LenLimitReached);
+    }
+
     [Fact]
     public void Basic_ShouldInitialiseCorrectly()
     {

dotnet/tests/ZB.MOM.NatsNet.Server.Tests/Internal/RateCounterTests.cs

@@ -22,6 +22,17 @@ namespace ZB.MOM.NatsNet.Server.Tests.Internal;
 /// </summary>
 public sealed class RateCounterTests
 {
+    [Fact]
+    public void NewRateCounter_ShouldCreateWithDefaultInterval()
+    {
+        var counter = RateCounter.NewRateCounter(2);
+        counter.Interval.ShouldBe(TimeSpan.FromSeconds(1));
+
+        counter.Allow().ShouldBeTrue();
+        counter.Allow().ShouldBeTrue();
+        counter.Allow().ShouldBeFalse();
+    }
+
     [Fact]
     public async Task RateCounter_ShouldAllowUpToLimitThenBlockAndReset()
     {

dotnet/tests/ZB.MOM.NatsNet.Server.Tests/Internal/ServerUtilitiesTests.cs

@@ -11,7 +11,10 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+using System.Net;
+using System.Text.Json;
 using Shouldly;
+using ZB.MOM.NatsNet.Server;
 using ZB.MOM.NatsNet.Server.Internal;
 
 namespace ZB.MOM.NatsNet.Server.Tests.Internal;
@@ -191,4 +194,86 @@ public sealed class ServerUtilitiesTests
                     $"VersionAtLeast({version}, {major}, {minor}, {update})");
         }
     }
+
+    [Fact]
+    public void RefCountedUrlSet_Wrappers_ShouldTrackRefCounts()
+    {
+        var set = new RefCountedUrlSet();
+        ServerUtilities.AddUrl(set, "nats://a:4222").ShouldBeTrue();
+        ServerUtilities.AddUrl(set, "nats://a:4222").ShouldBeFalse();
+        ServerUtilities.AddUrl(set, "nats://b:4222").ShouldBeTrue();
+
+        ServerUtilities.RemoveUrl(set, "nats://a:4222").ShouldBeFalse();
+        ServerUtilities.RemoveUrl(set, "nats://a:4222").ShouldBeTrue();
+
+        var urls = ServerUtilities.GetAsStringSlice(set);
+        urls.Length.ShouldBe(1);
+        urls[0].ShouldBe("nats://b:4222");
+    }
+
+    [Fact]
+    public async Task NatsDialTimeout_ShouldConnectWithinTimeout()
+    {
+        using var listener = new System.Net.Sockets.TcpListener(IPAddress.Loopback, 0);
+        listener.Start();
+        var port = ((IPEndPoint)listener.LocalEndpoint).Port;
+        var acceptTask = listener.AcceptTcpClientAsync();
+
+        using var client = await ServerUtilities.NatsDialTimeout(
+            "tcp",
+            $"127.0.0.1:{port}",
+            TimeSpan.FromSeconds(2));
+
+        client.Connected.ShouldBeTrue();
+        using var accepted = await acceptTask;
+        accepted.Connected.ShouldBeTrue();
+    }
+
+    [Fact]
+    public void GenerateInfoJSON_ShouldEmitInfoLineWithCRLF()
+    {
+        var info = new ServerInfo
+        {
+            Id = "S1",
+            Name = "n1",
+            Host = "127.0.0.1",
+            Port = 4222,
+            Version = "2.0.0",
+            Proto = 1,
+            GoVersion = "go1.23",
+        };
+
+        var bytes = ServerUtilities.GenerateInfoJSON(info);
+        var line = System.Text.Encoding.UTF8.GetString(bytes);
+        line.ShouldStartWith("INFO ");
+        line.ShouldEndWith("\r\n");
+
+        var json = line["INFO ".Length..^2];
+        var payload = JsonSerializer.Deserialize<ServerInfo>(json);
+        payload.ShouldNotBeNull();
+        payload!.Id.ShouldBe("S1");
+    }
+
+    [Fact]
+    public async Task ParallelTaskQueue_ShouldExecuteQueuedActions()
+    {
+        var writer = ServerUtilities.ParallelTaskQueue(maxParallelism: 2);
+        var ran = 0;
+        var tcs = new TaskCompletionSource(TaskCreationOptions.RunContinuationsAsynchronously);
+
+        for (var i = 0; i < 4; i++)
+        {
+            var accepted = writer.TryWrite(() =>
+            {
+                if (Interlocked.Increment(ref ran) == 4)
+                    tcs.TrySetResult();
+            });
+            accepted.ShouldBeTrue();
+        }
+
+        writer.TryComplete().ShouldBeTrue();
+        var finished = await Task.WhenAny(tcs.Task, Task.Delay(TimeSpan.FromSeconds(2)));
+        finished.ShouldBe(tcs.Task);
+        ran.ShouldBe(4);
+    }
 }

dotnet/tests/ZB.MOM.NatsNet.Server.Tests/Internal/SignalHandlerTests.cs

@@ -35,6 +35,16 @@ public sealed class SignalHandlerTests : IDisposable
         SignalHandler.CommandToUnixSignal(ServerCommand.LameDuckMode).ShouldBe(UnixSignal.SigUsr2);
     }
 
+    [Fact]
+    public void CommandToSignal_ShouldMatchCommandToUnixSignal()
+    {
+        foreach (var command in Enum.GetValues<ServerCommand>())
+        {
+            SignalHandler.CommandToSignal(command)
+                .ShouldBe(SignalHandler.CommandToUnixSignal(command));
+        }
+    }
+
     [Fact] // T:3155
     public void SetProcessName_ShouldNotThrow()
     {