Resource subscribe should be true if handler provided (#676)

Co-authored-by: Stephen Halter <[email protected]>
Co-authored-by: Mike Kistler <[email protected]>

Author: 3 people

src/ModelContextProtocol/McpServerOptionsSetup.cs

@@ -97,13 +97,14 @@ private static void OverwriteWithSetHandlers(McpServerHandlers handlers, McpServ
             optionsHandlers.ListResourceTemplatesHandler = handlers.ListResourceTemplatesHandler ?? optionsHandlers.ListResourceTemplatesHandler;
             optionsHandlers.ListResourcesHandler = handlers.ListResourcesHandler ?? optionsHandlers.ListResourcesHandler;
             optionsHandlers.ReadResourceHandler = handlers.ReadResourceHandler ?? optionsHandlers.ReadResourceHandler;
+        }
 
-            if (handlers.SubscribeToResourcesHandler is not null || handlers.UnsubscribeFromResourcesHandler is not null)
-            {
-                optionsHandlers.SubscribeToResourcesHandler = handlers.SubscribeToResourcesHandler ?? optionsHandlers.SubscribeToResourcesHandler;
-                optionsHandlers.UnsubscribeFromResourcesHandler = handlers.UnsubscribeFromResourcesHandler ?? optionsHandlers.UnsubscribeFromResourcesHandler;
-                resourcesCapability.Subscribe = true;
-            }
+        if (handlers.SubscribeToResourcesHandler is not null || handlers.UnsubscribeFromResourcesHandler is not null)
+        {
+            resourcesCapability ??= new();
+            optionsHandlers.SubscribeToResourcesHandler = handlers.SubscribeToResourcesHandler ?? optionsHandlers.SubscribeToResourcesHandler;
+            optionsHandlers.UnsubscribeFromResourcesHandler = handlers.UnsubscribeFromResourcesHandler ?? optionsHandlers.UnsubscribeFromResourcesHandler;
+            resourcesCapability.Subscribe = true;
         }
 
         ToolsCapability? toolsCapability = options.Capabilities?.Tools;

tests/ModelContextProtocol.AspNetCore.Tests/ServerConformanceTests.cs

@@ -110,21 +110,6 @@ public async Task RunConformanceTests()
 
     private void StartConformanceServer()
     {
-        // The ConformanceServer binary is in a parallel directory to the test binary
-        // Test binary is in: artifacts/bin/ModelContextProtocol.ConformanceTests/Debug/{tfm}/
-        // ConformanceServer binary is in: artifacts/bin/ModelContextProtocol.ConformanceServer/Debug/{tfm}/
-        var testBinaryDir = AppContext.BaseDirectory; // e.g., .../net10.0/
-        var configuration = Path.GetFileName(Path.GetDirectoryName(testBinaryDir.TrimEnd(Path.DirectorySeparatorChar))!);
-        var targetFramework = Path.GetFileName(testBinaryDir.TrimEnd(Path.DirectorySeparatorChar));
-        var conformanceServerDir = Path.GetFullPath(
-            Path.Combine(testBinaryDir, "..", "..", "..", "ModelContextProtocol.ConformanceServer", configuration, targetFramework));
-
-        if (!Directory.Exists(conformanceServerDir))
-        {
-            throw new DirectoryNotFoundException(
-                $"ConformanceServer directory not found at: {conformanceServerDir}");
-        }
-
         // Start the server in a background task
         _serverCts = new CancellationTokenSource();
         _serverTask = Task.Run(() => ConformanceServer.Program.MainAsync(["--urls", _serverUrl], new XunitLoggerProvider(_output), cancellationToken: _serverCts.Token));

tests/ModelContextProtocol.ConformanceServer/Program.cs

@@ -1,12 +1,9 @@
 using ConformanceServer.Prompts;
 using ConformanceServer.Resources;
 using ConformanceServer.Tools;
-using Microsoft.Extensions.AI;
 using ModelContextProtocol.Protocol;
 using System.Collections.Concurrent;
 using System.Text.Json;
-using System.Text.Json.Nodes;
-using System.Text.Json.Serialization;
 
 namespace ModelContextProtocol.ConformanceServer;
 
@@ -41,18 +38,8 @@ public static async Task MainAsync(string[] args, ILoggerProvider? loggerProvide
                 }
                 if (ctx.Params?.Uri is { } uri)
                 {
-                    subscriptions[ctx.Server.SessionId].TryAdd(uri, 0);
-
-                    await ctx.Server.SampleAsync([
-                        new ChatMessage(ChatRole.System, "You are a helpful test server"),
-                        new ChatMessage(ChatRole.User, $"Resource {uri}, context: A new subscription was started"),
-                    ],
-                    chatOptions: new ChatOptions
-                    {
-                        MaxOutputTokens = 100,
-                        Temperature = 0.7f,
-                    },
-                    cancellationToken: ct);
+                    var sessionSubscriptions = subscriptions.GetOrAdd(ctx.Server.SessionId, _ => new());
+                    sessionSubscriptions.TryAdd(uri, 0);
                 }
 
                 return new EmptyResult();
@@ -67,6 +54,7 @@ await ctx.Server.SampleAsync([
                 {
                     subscriptions[ctx.Server.SessionId].TryRemove(uri, out _);
                 }
+
                 return new EmptyResult();
             })
             .WithCompleteHandler(async (ctx, ct) =>

tests/ModelContextProtocol.Tests/Configuration/McpServerOptionsSetupTests.cs

@@ -108,29 +108,31 @@ public void Configure_WithUnsubscribeFromResourcesHandler_And_WithOtherResources
     }
 
     [Fact]
-    public void Configure_WithSubscribeToResourcesHandler_WithoutOtherResourcesHandler_DoesNotCreateResourcesCapability()
+    public void Configure_WithSubscribeToResourcesHandler_WithoutOtherResourcesHandler_DoesCreateResourcesCapability()
     {
         var services = new ServiceCollection();
         services.AddMcpServer()
             .WithSubscribeToResourcesHandler(async (request, ct) => new EmptyResult());
 
         var options = services.BuildServiceProvider().GetRequiredService<IOptions<McpServerOptions>>().Value;
 
-        Assert.Null(options.Handlers.SubscribeToResourcesHandler);
-        Assert.Null(options.Capabilities?.Resources);
+        Assert.NotNull(options.Handlers.SubscribeToResourcesHandler);
+        Assert.NotNull(options.Capabilities?.Resources);
+        Assert.True(options.Capabilities.Resources.Subscribe);
     }
 
     [Fact]
-    public void Configure_WithUnsubscribeFromResourcesHandler_WithoutOtherResourcesHandler_DoesNotCreateResourcesCapability()
+    public void Configure_WithUnsubscribeFromResourcesHandler_WithoutOtherResourcesHandler_DoesCreateResourcesCapability()
     {
         var services = new ServiceCollection();
         services.AddMcpServer()
             .WithUnsubscribeFromResourcesHandler(async (request, ct) => new EmptyResult());
 
         var options = services.BuildServiceProvider().GetRequiredService<IOptions<McpServerOptions>>().Value;
 
-        Assert.Null(options.Handlers.UnsubscribeFromResourcesHandler);
-        Assert.Null(options.Capabilities?.Resources);
+        Assert.NotNull(options.Handlers.UnsubscribeFromResourcesHandler);
+        Assert.NotNull(options.Capabilities?.Resources);
+        Assert.True(options.Capabilities.Resources.Subscribe);
     }
 
     [Fact]