# File test/test_params.rb, line 1606
    def test_argument_password
      init_arguments
      assert_equal(nil, @entry.args[1])
      @entry.set_arg_at(1, 'secret')
      assert_equal('secret', @entry.args[1])
      @entry.set_arg_at(1, nil) # allowd
      assert_exception(RuntimeError) {
        @entry.set_arg_at(1, :secret) # not allowed
      }
    end