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: failure_app_test.rb
    path of file: ./repos/stackneveroverflow/vendor/bundle/ruby/2.3.0/gems/devise-4.3.0/test
    
    the code of the file until where you have to start completion: require 'test_helper'
require 'ostruct'

class FailureTest < ActiveSupport::TestCase
  class RootFailureApp < Devise::Failur
    
  def call_failure(env_params={})
    env = {
      'REQUEST_URI' => 'http://test.host/',
      'HTTP_HOST' => 'test.host',
      'REQUEST_METHOD' => 'GET',
      'warden.options' => { scope: :user },
      'rack.session' => {},
      'action_dispatch.request.formats' => Array(env_params.delete('formats') || Mime[:html]),
      'rack.input' => "",
      'warden' => OpenStruct.new(message: nil)
    }.merge!(env_params)

    # Passing nil for action_dispatch.request.formats prevents the default from being used in Rails 5, need to remove it
    if env.has_key?('action_dispatch.request.formats') && env['action_dispatch.request.formats'].nil?
      env.delete 'action_dispatch.request.formats' unless env['action_dispatch.request.formats']
    end