Rename 29 ImplBacklog test files from .Impltests.cs to .cs to match PortTracker class names

dotnet/tests/ZB.MOM.NatsNet.Server.Tests/ImplBacklog/AuthHandlerTests.cs

@@ -0,0 +1,49 @@
+using Shouldly;
+using ZB.MOM.NatsNet.Server;
+using ZB.MOM.NatsNet.Server.Auth;
+using ZB.MOM.NatsNet.Server.Internal;
+
+namespace ZB.MOM.NatsNet.Server.Tests.ImplBacklog;
+
+public sealed class AuthHandlerTests
+{
+    [Fact] // T:149
+    public void NoAuthUser_ShouldSucceed()
+    {
+        var opts = new ServerOptions
+        {
+            Users = [new User { Username = "alice" }],
+        };
+
+        AuthHandler.ValidateNoAuthUser(opts, "alice").ShouldBeNull();
+        var missingUser = AuthHandler.ValidateNoAuthUser(opts, "bob");
+        missingUser.ShouldNotBeNull();
+        missingUser!.Message.ShouldContain("not present as user or nkey");
+    }
+
+    [Fact] // T:150
+    public void NoAuthUserNkey_ShouldSucceed()
+    {
+        var opts = new ServerOptions
+        {
+            Nkeys = [new NkeyUser { Nkey = "NKEY1" }],
+        };
+
+        AuthHandler.ValidateNoAuthUser(opts, "NKEY1").ShouldBeNull();
+        AuthHandler.ValidateNoAuthUser(opts, "NKEY2").ShouldNotBeNull();
+    }
+
+    [Fact] // T:152
+    public void NoAuthUserNoConnectProto_ShouldSucceed()
+    {
+        var opts = new ServerOptions
+        {
+            Users = [new User { Username = "alice" }],
+        };
+
+        var err = AuthHandler.ValidateNoAuthUser(opts, "bob");
+        err.ShouldNotBeNull();
+        err!.Message.ShouldContain("not present as user or nkey");
+    }
+
+}