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: test_digest.rb
    path of file: ./repos/stackneveroverflow/vendor/bundle/ruby/2.3.0/gems/mini_portile2-2.2.0/test
    
    the code of the file until where you have to start completion: require File.expand_path('../helper', __FILE__)

class TestDigest < TestCase
  attr :assets_path, :tar_path, :recipe

  def before_all
    super
    @assets_path = File.expand_path("../assets", __FILE_
    
  def test_with_invalid_gpg_signature
    data_file = File.expand_path(File.join(File.dirname(__FILE__), 'assets', 'gpg-fixtures', 'data'))

    @recipe.files << {
      :url => "file://#{data_file}",
      :gpg => {
        :key => public_key,
        :signature_url => "file://#{data_file}.invalid.asc"
      }
    }
    exception = assert_raises(RuntimeError){
      @recipe.download
    }
    assert_equal("signature mismatch", exception.message)
  end