✅ Add FakeServer#unsolicited (for testing)

Author: nevans

test/net/imap/fake_server.rb

@@ -103,6 +103,9 @@ def state; connection.state end
   # See CommandRouter#on
   def on(...) connection&.on(...) end
 
+  # See Connection#unsolicited
+  def unsolicited(...) @mutex.synchronize { connection&.unsolicited(...) } end
+
   private
 
   attr_reader :tcp_server, :connection

test/net/imap/fake_server/connection.rb

@@ -19,6 +19,7 @@ def initialize(server, tcp_socket:)
 
     def commands; state.commands end
     def on(...) router.on(...) end
+    def unsolicited(...) writer.untagged(...) end
 
     def run
       writer.greeting