# File lib/spec/mocks/message_expectation.rb, line 165
      def invoke_return_block(args, block)
        args << block unless block.nil?
        # Ruby 1.9 - when we set @return_block to return values
        # regardless of arguments, any arguments will result in
        # a "wrong number of arguments" error
        @return_block.arity > 0 ? @return_block.call(*args) : @return_block.call()
      end