Add notifications test

Author: stephentoub

tests/ModelContextProtocol.Tests/Configuration/McpServerBuilderExtensionsToolsTests.cs

@@ -9,6 +9,8 @@
 using ModelContextProtocol.Tests.Transport;
 using System.Text.RegularExpressions;
 using Microsoft.Extensions.AI;
+using System.Threading.Channels;
+using ModelContextProtocol.Protocol.Messages;
 
 namespace ModelContextProtocol.Tests.Configuration;
 
@@ -83,6 +85,45 @@ public async Task Can_List_Registered_Tools()
         Assert.Equal("Echoes the input back to the client.", doubleEchoTool.Description);
     }
 
+    [Fact]
+    public async Task Can_Be_Notified_Of_Tool_Changes()
+    {
+        IMcpClient client = await CreateMcpClientForServer();
+
+        var tools = await client.ListToolsAsync(TestContext.Current.CancellationToken);
+        Assert.Equal(10, tools.Count);
+
+        Channel<JsonRpcNotification> listChanged = Channel.CreateUnbounded<JsonRpcNotification>();
+        client.AddNotificationHandler("notifications/tools/list_changed", notification =>
+        {
+            listChanged.Writer.TryWrite(notification);
+            return Task.CompletedTask;
+        });
+
+        var notificationRead = listChanged.Reader.ReadAsync(TestContext.Current.CancellationToken);
+        Assert.False(notificationRead.IsCompleted);
+
+        var serverTools = _server.ServerOptions.Capabilities?.Tools?.ToolCollection;
+        Assert.NotNull(serverTools);
+
+        var newTool = McpServerTool.Create([McpServerTool(name: "NewTool")] () => "42");
+        serverTools.Add(newTool);
+        await notificationRead;
+
+        tools = await client.ListToolsAsync(TestContext.Current.CancellationToken);
+        Assert.Equal(11, tools.Count);
+        Assert.Contains(tools, t => t.Name == "NewTool");
+
+        notificationRead = listChanged.Reader.ReadAsync(TestContext.Current.CancellationToken);
+        Assert.False(notificationRead.IsCompleted);
+        serverTools.Remove(newTool);
+        await notificationRead;
+
+        tools = await client.ListToolsAsync(TestContext.Current.CancellationToken);
+        Assert.Equal(10, tools.Count);
+        Assert.DoesNotContain(tools, t => t.Name == "NewTool");
+    }
+
     [Fact]
     public async Task Can_Call_Registered_Tool()
     {