Add notification support

Co-authored-by: Kevin Fischer <kfischer_okarin@yahoo.co.jp>

test/mcp/server_notification_test.rb

@@ -0,0 +1,136 @@
+# typed: true
+# frozen_string_literal: true
+
+require "test_helper"
+
+module MCP
+  class ServerNotificationTest < ActiveSupport::TestCase
+    include InstrumentationTestHelper
+
+    class MockTransport < Transport
+      attr_reader :notifications
+
+      def initialize(server)
+        super
+        @notifications = []
+      end
+
+      def send_notification(method, params = nil)
+        @notifications << { method: method, params: params }
+        true
+      end
+
+      def send_response(response); end
+      def open; end
+      def close; end
+      def handle_request(request); end
+    end
+
+    setup do
+      configuration = MCP::Configuration.new
+      configuration.instrumentation_callback = instrumentation_helper.callback
+      
+      @server = Server.new(
+        name: "test_server",
+        version: "1.0.0",
+        configuration: configuration
+      )
+      
+      @mock_transport = MockTransport.new(@server)
+      @server.transport = @mock_transport
+    end
+
+    test "#notify_tools_list_changed sends notification through transport" do
+      @server.notify_tools_list_changed
+
+      assert_equal 1, @mock_transport.notifications.size
+      notification = @mock_transport.notifications.first
+      assert_equal Methods::NOTIFICATIONS_TOOLS_LIST_CHANGED, notification[:method]
+      assert_nil notification[:params]
+    end
+
+    test "#notify_prompts_list_changed sends notification through transport" do
+      @server.notify_prompts_list_changed
+
+      assert_equal 1, @mock_transport.notifications.size
+      notification = @mock_transport.notifications.first
+      assert_equal Methods::NOTIFICATIONS_PROMPTS_LIST_CHANGED, notification[:method]
+      assert_nil notification[:params]
+    end
+
+    test "#notify_resources_list_changed sends notification through transport" do
+      @server.notify_resources_list_changed
+
+      assert_equal 1, @mock_transport.notifications.size
+      notification = @mock_transport.notifications.first
+      assert_equal Methods::NOTIFICATIONS_RESOURCES_LIST_CHANGED, notification[:method]
+      assert_nil notification[:params]
+    end
+
+    test "notification methods work without transport" do
+      server_without_transport = Server.new(name: "test_server")
+      
+      # Should not raise any errors
+      assert_nothing_raised do
+        server_without_transport.notify_tools_list_changed
+        server_without_transport.notify_prompts_list_changed
+        server_without_transport.notify_resources_list_changed
+      end
+    end
+
+    test "notification methods handle transport errors gracefully" do
+      # Create a transport that raises errors
+      error_transport = Class.new(MockTransport) do
+        def send_notification(method, params = nil)
+          raise StandardError, "Transport error"
+        end
+      end.new(@server)
+      
+      @server.transport = error_transport
+      
+      # Mock the exception reporter
+      expected_contexts = [
+        { notification: "tools_list_changed" },
+        { notification: "prompts_list_changed" },
+        { notification: "resources_list_changed" }
+      ]
+      
+      call_count = 0
+      @server.configuration.exception_reporter.expects(:call).times(3).with do |exception, context|
+        assert_kind_of StandardError, exception
+        assert_equal "Transport error", exception.message
+        assert_includes expected_contexts, context
+        call_count += 1
+        true
+      end
+      
+      # Should not raise errors to the caller
+      assert_nothing_raised do
+        @server.notify_tools_list_changed
+        @server.notify_prompts_list_changed
+        @server.notify_resources_list_changed
+      end
+      
+      assert_equal 3, call_count
+    end
+
+    test "multiple notification methods can be called in sequence" do
+      @server.notify_tools_list_changed
+      @server.notify_prompts_list_changed
+      @server.notify_resources_list_changed
+
+      assert_equal 3, @mock_transport.notifications.size
+      
+      notifications = @mock_transport.notifications
+      assert_equal Methods::NOTIFICATIONS_TOOLS_LIST_CHANGED, notifications[0][:method]
+      assert_equal Methods::NOTIFICATIONS_PROMPTS_LIST_CHANGED, notifications[1][:method]
+      assert_equal Methods::NOTIFICATIONS_RESOURCES_LIST_CHANGED, notifications[2][:method]
+    end
+
+    test "notification method constants are defined correctly" do
+      assert_equal "notifications/tools/list_changed", Methods::NOTIFICATIONS_TOOLS_LIST_CHANGED
+      assert_equal "notifications/prompts/list_changed", Methods::NOTIFICATIONS_PROMPTS_LIST_CHANGED
+      assert_equal "notifications/resources/list_changed", Methods::NOTIFICATIONS_RESOURCES_LIST_CHANGED
+    end
+  end
+end