Rename the example file names related to SSE.

This PR renamed the files related to the SSE example and fixed the README.md.
Because missing files were specified in README.md.

And also, I removed the word 'test' from the file names related to the SSE example.
Other examples file names do not contain the word `test`.

examples/streamable_http_server.rb

@@ -0,0 +1,173 @@
+#!/usr/bin/env ruby
+# frozen_string_literal: true
+
+$LOAD_PATH.unshift(File.expand_path("../lib", __dir__))
+require "mcp"
+require "mcp/server/transports/streamable_http_transport"
+require "rack"
+require "rackup"
+require "json"
+require "logger"
+
+# Create a logger for SSE-specific logging
+sse_logger = Logger.new($stdout)
+sse_logger.formatter = proc do |severity, datetime, _progname, msg|
+  "[SSE] #{severity} #{datetime.strftime("%H:%M:%S.%L")} - #{msg}\n"
+end
+
+# Tool that returns a response that will be sent via SSE if a stream is active
+class NotificationTool < MCP::Tool
+  tool_name "notification_tool"
+  description "Returns a notification message that will be sent via SSE if stream is active"
+  input_schema(
+    properties: {
+      message: { type: "string", description: "Message to send via SSE" },
+      delay: { type: "number", description: "Delay in seconds before returning (optional)" },
+    },
+    required: ["message"],
+  )
+
+  class << self
+    attr_accessor :logger
+
+    def call(message:, delay: 0)
+      sleep(delay) if delay > 0
+
+      logger&.info("Returning notification message: #{message}")
+
+      MCP::Tool::Response.new([{
+        type: "text",
+        text: "Notification: #{message} (timestamp: #{Time.now.iso8601})",
+      }])
+    end
+  end
+end
+
+# Create the server
+server = MCP::Server.new(
+  name: "sse_test_server",
+  tools: [NotificationTool],
+  prompts: [],
+  resources: [],
+)
+
+# Set logger for tools
+NotificationTool.logger = sse_logger
+
+# Add a simple echo tool for basic testing
+server.define_tool(
+  name: "echo",
+  description: "Simple echo tool",
+  input_schema: { properties: { message: { type: "string" } }, required: ["message"] },
+) do |message:|
+  MCP::Tool::Response.new([{ type: "text", text: "Echo: #{message}" }])
+end
+
+# Create the Streamable HTTP transport
+transport = MCP::Server::Transports::StreamableHTTPTransport.new(server)
+server.transport = transport
+
+# Create a logger for MCP request/response logging
+mcp_logger = Logger.new($stdout)
+mcp_logger.formatter = proc do |_severity, _datetime, _progname, msg|
+  "[MCP] #{msg}\n"
+end
+
+# Create the Rack application
+app = proc do |env|
+  request = Rack::Request.new(env)
+
+  # Log request details
+  if request.post?
+    body = request.body.read
+    request.body.rewind
+    begin
+      parsed_body = JSON.parse(body)
+      mcp_logger.info("Request: #{parsed_body["method"]} (id: #{parsed_body["id"]})")
+
+      # Log SSE-specific setup
+      if parsed_body["method"] == "initialize"
+        sse_logger.info("New client initializing session")
+      end
+    rescue JSON::ParserError
+      mcp_logger.warn("Invalid JSON in request")
+    end
+  elsif request.get?
+    session_id = request.env["HTTP_MCP_SESSION_ID"] ||
+      Rack::Utils.parse_query(request.env["QUERY_STRING"])["sessionId"]
+    sse_logger.info("SSE connection request for session: #{session_id}")
+  end
+
+  # Handle the request
+  response = transport.handle_request(request)
+
+  # Log response details
+  status, headers, body = response
+  if body.is_a?(Array) && !body.empty? && request.post?
+    begin
+      parsed_response = JSON.parse(body.first)
+      if parsed_response["error"]
+        mcp_logger.error("Response error: #{parsed_response["error"]["message"]}")
+      elsif parsed_response["accepted"]
+        # Response was sent via SSE
+        sse_logger.info("Response sent via SSE stream")
+      else
+        mcp_logger.info("Response: success (id: #{parsed_response["id"]})")
+
+        # Log session ID for initialization
+        if headers["Mcp-Session-Id"]
+          sse_logger.info("Session created: #{headers["Mcp-Session-Id"]}")
+        end
+      end
+    rescue JSON::ParserError
+      mcp_logger.warn("Invalid JSON in response")
+    end
+  elsif request.get? && status == 200
+    sse_logger.info("SSE stream established")
+  end
+
+  response
+end
+
+# Build the Rack application with middleware
+rack_app = Rack::Builder.new do
+  use(Rack::CommonLogger, Logger.new($stdout))
+  use(Rack::ShowExceptions)
+  run(app)
+end
+
+# Print usage instructions
+puts "=== MCP Streaming HTTP Test Server ==="
+puts ""
+puts "Starting server on http://localhost:9393"
+puts ""
+puts "Available Tools:"
+puts "1. NotificationTool - Returns messages that are sent via SSE when stream is active"
+puts "2. echo - Simple echo tool"
+puts ""
+puts "Testing SSE:"
+puts ""
+puts "1. Initialize session:"
+puts '   curl -X POST http://localhost:9393 -H "Content-Type: application/json" \\'
+puts '     -d \'{"jsonrpc":"2.0","method":"initialize","id":1,"params":{"protocolVersion":"2024-11-05","capabilities":{},"clientInfo":{"name":"sse-test","version":"1.0"}}}\''
+puts ""
+puts "2. Connect SSE stream (use the session ID from step 1):"
+puts '   curl -N -H "Mcp-Session-Id: YOUR_SESSION_ID" http://localhost:9393'
+puts ""
+puts "3. In another terminal, test tools (responses will be sent via SSE if stream is active):"
+puts ""
+puts "   Echo tool:"
+puts '   curl -X POST http://localhost:9393 -H "Content-Type: application/json" -H "Mcp-Session-Id: YOUR_SESSION_ID" \\'
+puts '     -d \'{"jsonrpc":"2.0","method":"tools/call","id":2,"params":{"name":"echo","arguments":{"message":"Hello SSE!"}}}\''
+puts ""
+puts "   Notification tool (with 2 second delay):"
+puts '   curl -X POST http://localhost:9393 -H "Content-Type: application/json" -H "Mcp-Session-Id: YOUR_SESSION_ID" \\'
+puts '     -d \'{"jsonrpc":"2.0","method":"tools/call","id":3,"params":{"name":"notification_tool","arguments":{"message":"Hello SSE!", "delay": 2}}}\''
+puts ""
+puts "Note: When an SSE stream is active, tool responses will appear in the SSE stream and the POST request will return {\"accepted\": true}"
+puts ""
+puts "Press Ctrl+C to stop the server"
+puts ""
+
+# Start the server
+Rackup::Handler.get("puma").run(rack_app, Port: 9393, Host: "localhost")