ruby-sdk/test/mcp/server_notification_test.rb
Koichi ITO da2a7f80d7 Stream modern request notifications and honor the envelope logLevel per SEP-2575
## Motivation and Context

The modern (stateless) lifecycle of MCP 2026-07-28 serves each request as a self-contained exchange,
and two delivery requirements of that model were unimplemented:

- Notifications a handler emits while serving a modern request (progress, log messages)
  had nowhere to go: the modern path answered with a single JSON object,
  and the ephemeral per-request session degraded every notification to non-delivery.
  The conformance requirement expects them as frames on the request's own response stream
  (`tools-call-with-progress` fails with "No progress notifications received" at 2026-07-28).
- The envelope's `logLevel` member, which replaces the removed `logging/setLevel` RPC,
  was parsed but never applied: log delivery fell back to the server-wide level, violating the requirement
  that no `notifications/message` is sent for requests that did not set `_meta` `logLevel`.

The changes wire both up:

- `StreamableHTTPTransport#handle_modern` registers a per-request notification sink for its ephemeral session;
  `send_notification` routes into the sink ahead of the stateless guard.
  A request whose handler emitted notifications answers as an SSE stream carrying them ahead of the final response;
  a request that emitted none keeps the single JSON exchange and its HTTP status ladder.
- `Server#handle_request` applies the lifted envelope's `logLevel` to the session via the existing `configure_logging`,
  and on modern-era sessions `ServerSession#notify_log_message` no longer falls back to the server-wide level:
  without a per-request `logLevel` it stays silent, on every transport. An unrecognized level reads as absent,
  the safe direction, matching the Python SDK's `allowed_log_levels`.

The `server-stateless` scenario of the 2026-07-28 conformance requirements probes two stream-discipline
rules through diagnostic fixture tools the Ruby fixture did not define, so both checks failed as
not testable: `sep-2575-http-server-no-independent-requests-on-stream` calls `test_streaming_elicitation`
and requires that every frame on the request's response stream is a notification or the final response,
and `sep-2575-server-no-log-without-loglevel` calls `test_logging_tool` without an envelope `logLevel`
and requires that no `notifications/message` reaches the stream.

The fixture now defines both tools. `test_streaming_elicitation` reports progress and completes;
`test_logging_tool` calls `notify_log_message` unconditionally and relies on the SDK's per-request gate,
which drops the notification for modern requests that did not authorize logging through
`io.modelcontextprotocol/logLevel`. Both lean on the notification streaming this change adds:
with a `progressToken` or an authorizing `logLevel`, the notification is delivered as an SSE frame
ahead of the final response rather than being dropped.

One known limitation relative to the TypeScript and Python SDKs, which stream notifications live while the handler runs:
delivery here is buffered, flushing the frames after the handler returns. Ordering is preserved
and the conformance checks are satisfied, but long-running handlers get no real-time interleaving.
The sink is bounded (`MAX_MODERN_REQUEST_NOTIFICATIONS`, 1000): a handler emitting notifications
in proportion to client-supplied input cannot grow one request's memory without bound,
and past the cap the notify helpers report `false`, the same non-delivery degradation
they have on every other undeliverable path. Live streaming can follow without changing the wire shape.

## How Has This Been Tested?

`bundle exec rake test` passes with zero failures and RuboCop reports no offenses. New tests cover:
a modern `tools/call` streaming `notifications/progress` frames ahead of the result, the single JSON exchange staying
in place without notifications, log suppression without the envelope `logLevel`, log delivery with it,
the modern-era session ignoring the server-wide level while honoring a per-request one,
and the notification cap bounding one request's buffered frames while the notify helpers report `false` past it.

Against the conformance fixture server, the `tools-call-with-progress` progress check passes
at `--spec-version 2026-07-28` (its remaining wire-schema check belongs to the separate `resultType` change),
the stream-discipline checks `sep-2575-http-server-no-independent-requests-on-stream` and
`sep-2575-server-no-log-without-loglevel` report SUCCESS, and manual probes confirm the positive
directions the suite leaves untested: with `io.modelcontextprotocol/logLevel` in `_meta`,
`test_logging_tool` streams its `notifications/message` frame ahead of the result, and
with a `progressToken`, `test_streaming_elicitation` streams its `notifications/progress` frame.
The `--requirements 2025-11-25` server leg passes 78/78, unchanged.

## Breaking Changes

None for stable protocol versions: legacy requests and their notification delivery are unchanged.
Within the modern lifecycle, notifications become deliverable where they were previously dropped,
and log messages without a per-request `logLevel` stop leaking through the server-wide level,
as the specification requires.
2026-08-08 15:22:58 +09:00

316 lines
13 KiB
Ruby

# frozen_string_literal: true
require "test_helper"
module MCP
class ServerNotificationTest < ActiveSupport::TestCase
include InstrumentationTestHelper
include DeprecationWarningTestHelper
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)
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 "#notify_log_message sends notification through transport" do
@server.logging_message_notification = MCP::LoggingMessageNotification.new(level: "error")
@server.notify_log_message(data: { error: "Connection Failed" }, level: "error")
assert_equal 1, @mock_transport.notifications.size
assert_equal Methods::NOTIFICATIONS_MESSAGE, @mock_transport.notifications.first[:method]
assert_equal({ "data" => { error: "Connection Failed" }, "level" => "error" }, @mock_transport.notifications.first[:params])
end
test "#notify_log_message does not warn when no protocol version has been established" do
@server.logging_message_notification = MCP::LoggingMessageNotification.new(level: "error")
assert_no_deprecation_warning do
@server.notify_log_message(data: { error: "Connection Failed" }, level: "error")
end
assert_equal Methods::NOTIFICATIONS_MESSAGE, @mock_transport.notifications.first[:method]
end
test "#notify_log_message warns when configured protocol version is 2026-07-28" do
server = Server.new(
name: "test_server",
version: "1.0.0",
configuration: Configuration.new(protocol_version: "2026-07-28"),
)
mock_transport = MockTransport.new(server)
server.logging_message_notification = MCP::LoggingMessageNotification.new(level: "error")
assert_deprecation_warning(/MCP Logging .*2026-07-28/) do
server.notify_log_message(data: { error: "Connection Failed" }, level: "error")
end
assert_equal Methods::NOTIFICATIONS_MESSAGE, mock_transport.notifications.first[:method]
end
test "#notify_log_message warns when configured protocol version is 2026-07-28 without transport" do
server = Server.new(
name: "test_server",
version: "1.0.0",
configuration: Configuration.new(protocol_version: "2026-07-28"),
)
server.logging_message_notification = MCP::LoggingMessageNotification.new(level: "error")
assert_deprecation_warning(/MCP Logging .*2026-07-28/) do
server.notify_log_message(data: { error: "Connection Failed" }, level: "error")
end
end
test "#notify_log_message warns when configured protocol version is 2026-07-28 below configured level" do
server = Server.new(
name: "test_server",
version: "1.0.0",
configuration: Configuration.new(protocol_version: "2026-07-28"),
)
mock_transport = MockTransport.new(server)
server.logging_message_notification = MCP::LoggingMessageNotification.new(level: "error")
assert_deprecation_warning(/MCP Logging .*2026-07-28/) do
server.notify_log_message(data: { message: "test" }, level: "info")
end
assert_empty mock_transport.notifications
end
test "#notify_log_message does not warn when configured protocol version is older" do
server = Server.new(
name: "test_server",
version: "1.0.0",
configuration: Configuration.new(protocol_version: "2025-11-25"),
)
MockTransport.new(server)
server.logging_message_notification = MCP::LoggingMessageNotification.new(level: "error")
assert_no_deprecation_warning do
server.notify_log_message(data: { error: "Connection Failed" }, level: "error")
end
end
test "ServerSession#notify_log_message warns when negotiated protocol version is 2026-07-28 below configured level" do
server = Server.new(name: "test_server", version: "1.0.0")
mock_transport = MockTransport.new(server)
session = ServerSession.new(server: server, transport: mock_transport)
server.handle(
{
jsonrpc: "2.0",
method: "initialize",
id: 1,
params: {
protocolVersion: "2026-07-28",
capabilities: {},
clientInfo: { name: "test-client", version: "1.0" },
},
},
session: session,
)
session.configure_logging(MCP::LoggingMessageNotification.new(level: "error"))
assert_deprecation_warning(/MCP Logging .*2026-07-28/) do
session.notify_log_message(data: { message: "test" }, level: "info")
end
assert_empty mock_transport.notifications
end
test "ServerSession#notify_log_message on a modern-era session ignores the server-wide level" do
# SEP-2575: on the modern lifecycle, log delivery is authorized per request via
# the envelope's logLevel; the server-wide level MUST NOT apply.
server = Server.new(name: "test_server", version: "1.0.0")
mock_transport = MockTransport.new(server)
server.logging_message_notification = MCP::LoggingMessageNotification.new(level: "debug")
session = ServerSession.new(server: server, transport: mock_transport, era: :modern)
session.notify_log_message(data: { message: "test" }, level: "error")
assert_empty mock_transport.notifications
end
test "ServerSession#notify_log_message on a modern-era session honors a per-request level" do
server = Server.new(name: "test_server", version: "1.0.0")
mock_transport = MockTransport.new(server)
session = ServerSession.new(server: server, transport: mock_transport, era: :modern)
session.configure_logging(MCP::LoggingMessageNotification.new(level: "info"))
session.notify_log_message(data: { message: "test" }, level: "error")
assert_equal 1, mock_transport.notifications.length
assert_equal Methods::NOTIFICATIONS_MESSAGE, mock_transport.notifications.first[:method]
end
test "#notify_log_message sends notification with logger through transport" do
@server.logging_message_notification = MCP::LoggingMessageNotification.new(level: "error")
@server.notify_log_message(data: { error: "Connection Failed" }, level: "error", logger: "DatabaseLogger")
assert_equal 1, @mock_transport.notifications.size
notification = @mock_transport.notifications.first
assert_equal Methods::NOTIFICATIONS_MESSAGE, notification[:method]
assert_equal({ "data" => { error: "Connection Failed" }, "level" => "error", "logger" => "DatabaseLogger" }, notification[:params])
end
test "#notify_log_message does not send notification with invalid log level" do
@server.logging_message_notification = MCP::LoggingMessageNotification.new(level: "error")
@server.notify_log_message(data: { message: "test" }, level: "invalid")
assert_equal 0, @mock_transport.notifications.size
end
test "#notify_log_message does not send notification when level is below configured level" do
@server.logging_message_notification = MCP::LoggingMessageNotification.new(level: "error")
@server.notify_log_message(data: { message: "test" }, level: "info")
assert_equal 0, @mock_transport.notifications.size
end
test "#notify_log_message sends notification when level is above configured level through transport" do
@server.logging_message_notification = MCP::LoggingMessageNotification.new(level: "error")
@server.notify_log_message(data: { message: "test" }, level: "critical")
assert_equal 1, @mock_transport.notifications.size
assert_equal Methods::NOTIFICATIONS_MESSAGE, @mock_transport.notifications[0][:method]
assert_equal({ "data" => { message: "test" }, "level" => "critical" }, @mock_transport.notifications[0][:params])
end
test "notification methods work without transport" do
server_without_transport = Server.new(name: "test_server")
server_without_transport.logging_message_notification = MCP::LoggingMessageNotification.new(level: "error")
# 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
server_without_transport.notify_log_message(data: { error: "Connection Failed" }, level: "error")
end
end
test "notification methods handle transport errors gracefully" do
# Replace server's transport with one that raises on send_notification.
Class.new(MockTransport) do
def send_notification(method, params = nil)
raise StandardError, "Transport error"
end
end.new(@server)
@server.logging_message_notification = MCP::LoggingMessageNotification.new(level: "error")
# Mock the exception reporter
expected_contexts = [
{ notification: "tools_list_changed" },
{ notification: "prompts_list_changed" },
{ notification: "resources_list_changed" },
{ notification: "log_message" },
]
call_count = 0
@server.configuration.exception_reporter.expects(:call).times(4).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
@server.notify_log_message(data: { error: "Connection Failed" }, level: "error")
end
assert_equal 4, 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
@server.logging_message_notification = MCP::LoggingMessageNotification.new(level: "error")
@server.notify_log_message(data: { error: "Connection Failed" }, level: "error")
assert_equal 4, @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]
assert_equal Methods::NOTIFICATIONS_MESSAGE, notifications[3][:method]
end
test "server.notify_log_message works after logging/setLevel via session" do
session = ServerSession.new(server: @server, transport: @mock_transport)
# Client sends logging/setLevel through session.
@server.handle(
{ jsonrpc: "2.0", id: 1, method: "logging/setLevel", params: { level: "info" } },
session: session,
)
# Server-level broadcast should still work because logging level
# is stored on both the session and the server.
@server.notify_log_message(data: "broadcast log", level: "info")
log_notifications = @mock_transport.notifications.select { |n| n[:method] == Methods::NOTIFICATIONS_MESSAGE }
assert_equal 1, log_notifications.size
assert_equal "broadcast log", log_notifications.first[:params]["data"]
end
end
end