live_error.rb

require 'optparse'

unless File.exists?('Gemfile')
  File.write('Gemfile', <<-GEMFILE)
    source 'https://rubygems.org'
    gem 'rails', github: 'rails/rails'
  GEMFILE

  system 'bundle'
end

require 'bundler'
Bundler.setup(:default)

require 'rails'
require 'action_controller/railtie'

class TestApp < Rails::Application
  config.root = File.dirname(__FILE__)
  config.session_store :cookie_store, key: 'cookie_store_key'
  config.secret_token    = 'secret_token'
  config.secret_key_base = 'secret_key_base'

  config.logger = Logger.new($stdout)
  Rails.logger  = config.logger

  routes.draw do
    get '/' => 'test#index'
  end
end

class TestController < ActionController::Base
  OptionParser.new {|o| o.on('--include-live') {|live| include ActionController::Live}}.parse!
  def index
    raise "Error"
    response.stream.close
  end
end

require 'minitest/autorun'
require 'rack/test'

class BugTest < Minitest::Test
  include Rack::Test::Methods

  def test_errors
    get '/'
    assert last_response.server_error?, "Expected / to raise an error and return a 500"
  end

  private
    def app
      Rails.application
    end
end