Avoid docker port conflicts from test suites running concurrently

Author: stephentoub

tests/ModelContextProtocol.TestSseServer/Program.cs

@@ -377,10 +377,12 @@ public static async Task MainAsync(string[] args, ILoggerProvider? loggerProvide
     {
         Console.WriteLine("Starting server...");
 
+        int port = args.Length > 0 &&  uint.TryParse(args[0], out var parsedPort) ? (int)parsedPort : 3001;
+
         var builder = WebApplication.CreateSlimBuilder(args);
         builder.WebHost.ConfigureKestrel(options =>
         {
-            options.ListenLocalhost(3001);
+            options.ListenLocalhost(port);
         });
 
         ConfigureSerilog(builder.Logging);

tests/ModelContextProtocol.Tests/SseIntegrationTests.cs

@@ -8,11 +8,25 @@ namespace ModelContextProtocol.Tests;
 
 public class SseIntegrationTests(ITestOutputHelper outputHelper) : LoggedTest(outputHelper)
 {
+    /// <summary>Port number to be grabbed by the next test.</summary>
+    private static int s_nextPort = 3000;
+
+    // If the tests run concurrently against different versions of the runtime, tests can conflict with
+    // each other in the ports set up for interacting with containers. Ensure that such suites running
+    // against different TFMs use different port numbers.
+    private static readonly int s_portOffset = 1000 * (Environment.Version.Major switch
+    {
+        int v when v >= 8 => Environment.Version.Major - 7,
+        _ => 0,
+    });
+
+    private static int CreatePortNumber() => Interlocked.Increment(ref s_nextPort) + s_portOffset;
+
     [Fact]
     public async Task ConnectAndReceiveMessage_InMemoryServer()
     {
         // Arrange
-        await using InMemoryTestSseServer server = new(logger: LoggerFactory.CreateLogger<InMemoryTestSseServer>());
+        await using InMemoryTestSseServer server = new(CreatePortNumber(), LoggerFactory.CreateLogger<InMemoryTestSseServer>());
         await server.StartAsync();
 
         var defaultOptions = new McpClientOptions
@@ -26,7 +40,7 @@ public async Task ConnectAndReceiveMessage_InMemoryServer()
             Name = "In-memory Test Server",
             TransportType = TransportTypes.Sse,
             TransportOptions = [],
-            Location = "http://localhost:5000/sse"
+            Location = $"http://localhost:{server.Port}/sse"
         };
 
         // Act
@@ -52,7 +66,7 @@ public async Task ConnectAndReceiveMessage_EverythingServerWithSse()
     {
         Assert.SkipWhen(!EverythingSseServerFixture.IsDockerAvailable, "docker is not available");
 
-        int port = 3001;
+        int port = CreatePortNumber();
 
         await using var fixture = new EverythingSseServerFixture(port);
         await fixture.StartAsync();
@@ -89,7 +103,7 @@ public async Task Sampling_Sse_EverythingServer()
     {
         Assert.SkipWhen(!EverythingSseServerFixture.IsDockerAvailable, "docker is not available");
 
-        int port = 3002;
+        int port = CreatePortNumber();
 
         await using var fixture = new EverythingSseServerFixture(port);
         await fixture.StartAsync();
@@ -157,11 +171,10 @@ public async Task Sampling_Sse_EverythingServer()
     public async Task ConnectAndReceiveMessage_InMemoryServer_WithFullEndpointEventUri()
     {
         // Arrange
-        await using InMemoryTestSseServer server = new(logger: LoggerFactory.CreateLogger<InMemoryTestSseServer>());
+        await using InMemoryTestSseServer server = new(CreatePortNumber(), LoggerFactory.CreateLogger<InMemoryTestSseServer>());
         server.UseFullUrlForEndpointEvent = true;
         await server.StartAsync();
 
-
         var defaultOptions = new McpClientOptions
         {
             ClientInfo = new() { Name = "IntegrationTestClient", Version = "1.0.0" }
@@ -173,7 +186,7 @@ public async Task ConnectAndReceiveMessage_InMemoryServer_WithFullEndpointEventU
             Name = "In-memory Test Server",
             TransportType = TransportTypes.Sse,
             TransportOptions = [],
-            Location = "http://localhost:5000/sse"
+            Location = $"http://localhost:{server.Port}/sse"
         };
 
         // Act
@@ -197,7 +210,7 @@ public async Task ConnectAndReceiveMessage_InMemoryServer_WithFullEndpointEventU
     public async Task ConnectAndReceiveNotification_InMemoryServer()
     {
         // Arrange
-        await using InMemoryTestSseServer server = new(logger: LoggerFactory.CreateLogger<InMemoryTestSseServer>());
+        await using InMemoryTestSseServer server = new(CreatePortNumber(), LoggerFactory.CreateLogger<InMemoryTestSseServer>());
         await server.StartAsync();
 
 
@@ -212,7 +225,7 @@ public async Task ConnectAndReceiveNotification_InMemoryServer()
             Name = "In-memory Test Server",
             TransportType = TransportTypes.Sse,
             TransportOptions = [],
-            Location = "http://localhost:5000/sse"
+            Location = $"http://localhost:{server.Port}/sse"
         };
 
         // Act

tests/ModelContextProtocol.Tests/SseServerIntegrationTestFixture.cs

@@ -17,16 +17,19 @@ public class SseServerIntegrationTestFixture : IAsyncDisposable
 
     public SseServerIntegrationTestFixture()
     {
+        // Ensure that test suites running against different TFMs and possibly concurrently use different port numbers.
+        int port = 3001 + Environment.Version.Major;
+
         DefaultConfig = new McpServerConfig
         {
             Id = "test_server",
             Name = "TestServer",
             TransportType = TransportTypes.Sse,
             TransportOptions = [],
-            Location = "http://localhost:3001/sse"
+            Location = $"http://localhost:{port}/sse"
         };
 
-        _serverTask = Program.MainAsync([], new XunitLoggerProvider(_delegatingTestOutputHelper), _stopCts.Token);
+        _serverTask = Program.MainAsync([port.ToString()], new XunitLoggerProvider(_delegatingTestOutputHelper), _stopCts.Token);
     }
 
     public static McpClientOptions CreateDefaultClientOptions() => new()

tests/ModelContextProtocol.Tests/Utils/InMemoryTestSseServer.cs

@@ -26,6 +26,8 @@ public sealed class InMemoryTestSseServer : IAsyncDisposable
 
     public InMemoryTestSseServer(int port = 5000, ILogger<InMemoryTestSseServer>? logger = null)
     {
+        Port = port;
+
         _listener = new HttpListener();
         _listener.Prefixes.Add($"http://localhost:{port}/");
         _cts = new CancellationTokenSource();
@@ -35,6 +37,8 @@ public InMemoryTestSseServer(int port = 5000, ILogger<InMemoryTestSseServer>? lo
         _messagePath = "/message";
     }
 
+    public int Port { get; }
+
     /// <summary>
     /// This is to be able to use the full URL for the endpoint event.
     /// </summary>