feat: add PID file and ports file support

tests/NATS.Server.Tests/ServerTests.cs

@@ -842,3 +842,62 @@ public class LameDuckTests
         }
     }
 }
+
+public class PidFileTests : IDisposable
+{
+    private readonly string _tempDir = Path.Combine(Path.GetTempPath(), $"nats-test-{Guid.NewGuid():N}");
+
+    public PidFileTests() => Directory.CreateDirectory(_tempDir);
+
+    public void Dispose()
+    {
+        if (Directory.Exists(_tempDir))
+            Directory.Delete(_tempDir, recursive: true);
+    }
+
+    private static int GetFreePort()
+    {
+        using var sock = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
+        sock.Bind(new IPEndPoint(IPAddress.Loopback, 0));
+        return ((IPEndPoint)sock.LocalEndPoint!).Port;
+    }
+
+    [Fact]
+    public async Task Server_writes_pid_file_on_startup()
+    {
+        var pidFile = Path.Combine(_tempDir, "nats.pid");
+        var port = GetFreePort();
+        var server = new NatsServer(new NatsOptions { Port = port, PidFile = pidFile }, NullLoggerFactory.Instance);
+        _ = server.StartAsync(CancellationToken.None);
+        await server.WaitForReadyAsync();
+
+        File.Exists(pidFile).ShouldBeTrue();
+        var content = await File.ReadAllTextAsync(pidFile);
+        int.Parse(content).ShouldBe(Environment.ProcessId);
+
+        await server.ShutdownAsync();
+        File.Exists(pidFile).ShouldBeFalse();
+
+        server.Dispose();
+    }
+
+    [Fact]
+    public async Task Server_writes_ports_file_on_startup()
+    {
+        var port = GetFreePort();
+        var server = new NatsServer(new NatsOptions { Port = port, PortsFileDir = _tempDir }, NullLoggerFactory.Instance);
+        _ = server.StartAsync(CancellationToken.None);
+        await server.WaitForReadyAsync();
+
+        var portsFiles = Directory.GetFiles(_tempDir, "*.ports");
+        portsFiles.Length.ShouldBe(1);
+
+        var content = await File.ReadAllTextAsync(portsFiles[0]);
+        content.ShouldContain($"\"client\":{port}");
+
+        await server.ShutdownAsync();
+        Directory.GetFiles(_tempDir, "*.ports").Length.ShouldBe(0);
+
+        server.Dispose();
+    }
+}