rails路由使用路由断言在路由测试中设置请求头

Question

使用路由断言帮助程序编写测试，我想将请求标头设置为Facebook Share bot

class RoutesTest < ActionController::TestCase

    test 'route social share bot to bots controller' do
            assert_recognizes({controller: 'bots', action: 'index'}, '/careers/1', 
                { @request.headers['HTTP_USER_AGENT'] => 'facebookexternalhit/1.1 (+http://www.facebook.com/externalhit_uatext.php)' })
    end
end

测试记录实际识别的选项显示为

{
 "controller"=>"site/pages", 
 "action"=>"home", "path"=>"careers/1", 
 "Rails Testing"=>"facebookexternalhit/1.1 (+http://www.facebook.com/externalhit_uatext.php)"
}

这并不像我设置请求标头那样。我是否在这里正确设置用户代理标题有点困惑？

更新

通过ActionContoller :: TestCase文档，这应该有效

test 'route social share bot to bots controller' do
        @request.user_agent = 'facebookexternalhit/1.1 (+http://www.facebook.com/externalhit_uatext.php)'
        assert_recognizes({controller: 'site/bots', action: 'index', path: 'careers/1'}, '/careers/1')
end

但是也没有设置用户代理，我也尝试了@request.env['HTTP_USER_AGENT']风味