You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: definition_spec.rb
    path of file: ./repos/rubygems/bundler/spec/bundler
    
    the code of the file until where you have to start completion: # frozen_string_literal: true

require "bundler/definition"

R
    
  def mock_source_list
    Class.new do
      def all_sources
        []
      end

      def path_sources
        []
      end

      def rubygems_remotes
        []
      end

      def replace_sources!(arg)
        nil
      end
    end.new
  end
end