如何安装webkit_server插件？

Question

我使用capybara-webkit（1.11.1）使用rspec运行以下代码：

    require 'spec_helper'

feature 'burnins', js: true do

  let(:user) { User.first }
  let(:project) { Project.visible_to(user).first }
  let(:folder) { create(:folder, project: project) }
  let(:clip) { create(:clip) }
  let(:playlist) { create(:playlist, folder: folder, clips: [clip]) }

  before do
    quick_login(user)
  end

  describe 'create' do

    after do
      attach_file 'burnin_file', 'spec/fixtures/burnin.png'
      expect do
        click_button(I18n.t('project.upload_burnin'))
        expect(page).to have_content(I18n.t('project.choose_burnin_background'))
      end.to change { Burnin.count }.by(1)
    end

    context 'in playlist' do
      it 'should create burnin and open edit popup' do
        visit playlist_path(id: playlist.id)
        click_link('btn_panel_burnin_ajax')
        click_link(I18n.t('project.create_new_burnin'))
      end
    end

  end

end

执行此测试时会弹出此通知：

过了一会儿，它变成了：

有没有办法安装具有需求功能的插件？