refactor: rename remaining tests to NATS.Server.Core.Tests

- Rename tests/NATS.Server.Tests -> tests/NATS.Server.Core.Tests
- Update solution file, InternalsVisibleTo, and csproj references
- Remove JETSTREAM_INTEGRATION_MATRIX and NATS.NKeys from csproj (moved to JetStream.Tests and Auth.Tests)
- Update all namespaces from NATS.Server.Tests.* to NATS.Server.Core.Tests.*
- Replace private GetFreePort/ReadUntilAsync helpers with TestUtilities calls
- Fix stale namespace in Transport.Tests/NetworkingGoParityTests.cs

tests/NATS.Server.Core.Tests/SubList/SubListAsyncCacheSweepTests.cs

@@ -0,0 +1,22 @@
+using NATS.Server.Subscriptions;
+
+namespace NATS.Server.Core.Tests;
+
+public class SubListAsyncCacheSweepTests
+{
+    [Fact]
+    public async Task Cache_sweep_runs_async_and_prunes_stale_entries_without_write_locking_match_path()
+    {
+        using var sl = new SubList();
+        sl.Insert(new Subscription { Subject = ">", Sid = "all" });
+
+        for (var i = 0; i < 1500; i++)
+            _ = sl.Match($"orders.{i}");
+
+        var initial = sl.CacheCount;
+        initial.ShouldBeGreaterThan(1024);
+
+        await sl.TriggerCacheSweepAsyncForTest();
+        sl.CacheCount.ShouldBeLessThan(initial);
+    }
+}

tests/NATS.Server.Core.Tests/SubList/SubListHighFanoutOptimizationTests.cs

@@ -0,0 +1,22 @@
+using NATS.Server.Subscriptions;
+
+namespace NATS.Server.Core.Tests;
+
+public class SubListHighFanoutOptimizationTests
+{
+    [Fact]
+    public void High_fanout_nodes_enable_packed_list_optimization()
+    {
+        using var sl = new SubList();
+        for (var i = 0; i < 300; i++)
+        {
+            sl.Insert(new Subscription
+            {
+                Subject = "orders.created",
+                Sid = i.ToString(),
+            });
+        }
+
+        sl.HighFanoutNodeCountForTest.ShouldBeGreaterThan(0);
+    }
+}

tests/NATS.Server.Core.Tests/SubList/SubListMatchBytesTests.cs

@@ -0,0 +1,16 @@
+using NATS.Server.Subscriptions;
+
+namespace NATS.Server.Core.Tests;
+
+public class SubListMatchBytesTests
+{
+    [Fact]
+    public void MatchBytes_matches_subject_without_string_allocation_and_respects_remote_filter()
+    {
+        using var sl = new SubList();
+        sl.MatchBytes("orders.created"u8).PlainSubs.Length.ShouldBe(0);
+
+        sl.Insert(new Subscription { Subject = "orders.*", Sid = "1" });
+        sl.MatchBytes("orders.created"u8).PlainSubs.Length.ShouldBe(1);
+    }
+}

tests/NATS.Server.Core.Tests/SubList/SubListNotificationTests.cs

@@ -0,0 +1,24 @@
+using NATS.Server.Subscriptions;
+
+namespace NATS.Server.Core.Tests;
+
+public class SubListNotificationTests
+{
+    [Fact]
+    public void Interest_change_notifications_are_emitted_for_local_and_remote_changes()
+    {
+        using var sl = new SubList();
+        var changes = new List<InterestChange>();
+        sl.InterestChanged += changes.Add;
+
+        var sub = new Subscription { Subject = "orders.created", Sid = "1" };
+        sl.Insert(sub);
+        sl.Remove(sub);
+        sl.ApplyRemoteSub(new RemoteSubscription("orders.*", null, "r1", "A"));
+        sl.ApplyRemoteSub(RemoteSubscription.Removal("orders.*", null, "r1", "A"));
+
+        changes.Count.ShouldBe(4);
+        changes.Select(c => c.Kind).ShouldContain(InterestChangeKind.LocalAdded);
+        changes.Select(c => c.Kind).ShouldContain(InterestChangeKind.RemoteAdded);
+    }
+}

tests/NATS.Server.Core.Tests/SubList/SubListQueueWeightTests.cs

@@ -0,0 +1,17 @@
+using NATS.Server.Subscriptions;
+
+namespace NATS.Server.Core.Tests;
+
+public class SubListQueueWeightTests
+{
+    [Fact]
+    public void Remote_queue_weight_expands_matches()
+    {
+        using var sl = new SubList();
+        sl.ApplyRemoteSub(new RemoteSubscription("orders.*", "q", "r1", "A", QueueWeight: 3));
+
+        var matches = sl.MatchRemote("A", "orders.created");
+        matches.Count.ShouldBe(3);
+        matches.ShouldAllBe(m => m.Queue == "q");
+    }
+}

tests/NATS.Server.Core.Tests/SubList/SubListRemoteFilterTests.cs

@@ -0,0 +1,18 @@
+using NATS.Server.Subscriptions;
+
+namespace NATS.Server.Core.Tests;
+
+public class SubListRemoteFilterTests
+{
+    [Fact]
+    public void Match_remote_filters_by_account_and_subject()
+    {
+        using var sl = new SubList();
+        sl.ApplyRemoteSub(new RemoteSubscription("orders.*", null, "r1", "A"));
+        sl.ApplyRemoteSub(new RemoteSubscription("orders.*", null, "r2", "B"));
+
+        var aMatches = sl.MatchRemote("A", "orders.created");
+        aMatches.Count.ShouldBe(1);
+        aMatches[0].Account.ShouldBe("A");
+    }
+}