ruby-on-rails – 如何测试rails 4确认对话与Capybara和Polterge

链接正在使用rails’link_to：

link_to 'Delete',user_path,method: :delete,data: { confirm: "Are you sure?" }

并生成以下html：

<a data-confirm="Are you sure?" data-method="delete" href="/users/6" rel="nofollow">Delete</a>

该功能在浏览器中正常工作,但我想在我的rspec功能规范中进行测试.

我试图清除浏览器的确认功能,如here和this gist所述,但是我无法使其工作.

it 'requests confirmation',js: true do
  visit user_path(user)
  page.execute_script "
    window.confirmMsg = null;
    window.confirm = function(msg) { window.confirmMsg = msg; return true; };"
  click_link 'Delete'
  expect(page.evaluate_script('window.confirmMsg')).to eq('Are you sure?')
end

从rspec发出以下错误：

Failure/Error: expect(page.evaluate_script('window.confirmMsg')).to eq('Are you sure?')

       expected: "Are you sure?"
            got: nil

       (compared using ==)

但是,如果我直接通过page.execute_script直接打电话确认：

it 'requests confirmation',js: true do
  visit user_path(user)
  page.execute_script "
    window.confirmMsg = null;
    window.confirm = function(msg) { window.confirmMsg = msg; return true; };
    window.confirm('Are you sure?');"
  expect(page.evaluate_script('window.confirmMsg')).to eq('Are you sure?')
end

然后测试通过.

同时单击删除链接将导致测试失败,即使直接为page.execute_script调用确认：

it 'requests confirmation',js: true do
  visit user_path(user)
  page.execute_script "
    window.confirmMsg = null;
    window.confirm = function(msg) { window.confirmMsg = msg; return true; };
    window.confirm('Are you sure?');"
  click_link 'Delete'
  expect(page.evaluate_script('window.confirmMsg')).to eq('Are you sure?')
end

从rspec发出同样的错误：

Failure/Error: expect(page.evaluate_script('window.confirmMsg')).to eq('Are you sure?')

       expected: "Are you sure?"
            got: nil

       (compared using ==)

为什么测试失败？而且,如何正确地测试确认对话？

语境：

我从Vagrant虚拟机运行我的测试,这是Ubuntu 12.04.4 LTS和运行ruby 2.1.2p95.

我的Gemfile.lock显示我有以下版本：

rails (4.1.4)
poltergeist (1.5.1)
capybara (2.4.1)