设计请求环境 nil

如何解决设计请求环境 nil

关于控制器测试的设计自述部分表明

# Mimic the router behavior of setting the Devise scope through the env.
@request.env['devise.mapping'] = Devise.mappings[:user]

但是在下面的测试中

class UsersControllerTest < Actiondispatch::IntegrationTest
  include Devise::Test::IntegrationHelpers

test "should update user" do
  @request.env['devise.mapping'] = Devise.mappings[:user]
  sign_in users(:funky_mobile)
  login_name = users(:funky_mobile).login_name
  assert_changes login_name do
    patch user_registration_path(id: @user_mobile.id),params: { user: { address: 'muuvt',mobile: '7283699',mobile_nation_id: 1 } }
  end

测试立即出错

NoMethodError: undefined method `env' for nil:NilClass

应该如何使用 minitest 编写此测试来运行控制器逻辑？