Function TestSynchronousNotifications

mcp/mcp_test.go:1957–2022

(t *testing.T)

}

func TestSynchronousNotifications(t *testing.T) {
	synctest.Test(t, func(t *testing.T) {
		var toolsChanged atomic.Int32
		clientOpts := &ClientOptions{
			ToolListChangedHandler: func(ctx context.Context, req *ToolListChangedRequest) {
				toolsChanged.Add(1)
			},
			CreateMessageHandler: func(ctx context.Context, req *CreateMessageRequest) (*CreateMessageResult, error) {
				// See the comment after "from server" below.
				if n := toolsChanged.Load(); n != 1 {
					return nil, fmt.Errorf("got %d tools-changed notification, wanted 1", n)
				}
				// TODO(rfindley): investigate the error returned from this test if
				// CreateMessageResult is new(CreateMessageResult): it's a mysterious
				// unmarshalling error that we should improve.
				return &CreateMessageResult{Content: &TextContent{}}, nil
			},
		}
		client := NewClient(testImpl, clientOpts)

		var rootsChanged atomic.Bool
		serverOpts := &ServerOptions{
			RootsListChangedHandler: func(_ context.Context, req *RootsListChangedRequest) {
				rootsChanged.Store(true)
			},
		}
		server := NewServer(testImpl, serverOpts)
		addTool := func(s *Server) {
			AddTool(s, &Tool{Name: "tool"}, func(ctx context.Context, req *CallToolRequest, args any) (*CallToolResult, any, error) {
				if !rootsChanged.Load() {
					return nil, nil, fmt.Errorf("didn't get root change notification")
				}
				return new(CallToolResult), nil, nil
			})
		}
		cs, ss, cleanup := basicClientServerConnection(t, client, server, addTool)
		defer cleanup()

		t.Log("from client")
		{
			client.AddRoots(&Root{Name: "myroot", URI: "file://foo"})
			res, err := cs.CallTool(context.Background(), &CallToolParams{Name: "tool"})
			if err != nil {
				t.Fatalf("CallTool failed: %v", err)
			}
			if res.IsError {
				t.Errorf("tool error: %v", res.Content[0].(*TextContent).Text)
			}
		}

		t.Log("from server")
		{
			// Despite all this tool-changed activity, we expect only one notification.
			for range 10 {
				server.RemoveTools("tool")
				addTool(server)
			}