Failure case for notifications/initialized

Author: bigH

test/mcp/server/transports/streamable_http_transport_test.rb

@@ -665,7 +665,7 @@ class StreamableHTTPTransportTest < ActiveSupport::TestCase
           assert body["success"]
         end
 
-        test "stateless mode does not support notifications" do
+        test "stateless mode does not support server-sent events" do
           stateless_transport = StreamableHTTPTransport.new(@server, stateless: true)
 
           assert_raises(RuntimeError, "Stateless mode does not support notifications") do
@@ -677,6 +677,24 @@ class StreamableHTTPTransportTest < ActiveSupport::TestCase
           end
         end
 
+        test "stateless mode responds with 202 when client sends a notification/initialized request" do
+          stateless_transport = StreamableHTTPTransport.new(@server, stateless: true)
+
+          request = create_rack_request(
+            "POST",
+            "/",
+            { "CONTENT_TYPE" => "application/json" },
+            { jsonrpc: "2.0", method: "notifications/initialized" }.to_json,
+          )
+
+          response = stateless_transport.handle_request(request)
+          assert_equal 202, response[0]
+          assert_equal({ "Content-Type" => "application/json" }, response[1])
+
+          body = response[2][0]
+          assert body.blank?
+        end
+
         test "handle post request with a standard error" do
           request = create_rack_request(
             "POST",