如何在使用rescue_from时使用Rails4和RSpec测试渲染状态：404

我有一个带有“PagesController”的 Rails4 应用程序。

当找不到页面时，show-method 会抛出自定义异常“PageNotFoundError”。

在我定义的控制器之上rescue_from PageNotFoundError, with: :render_not_found

render not found是一个私有方法PagesController看起来像：

def render_not_found
  flash[:alert]=t(:page_does_not_exists, title: params[:id])
  @pages = Page.all
  render :index, status: :not_found #404
end

开发模式下的 Rails-log 显示：

Started GET "/pages/readmef" for 127.0.0.1 at 2013-08-02 23:11:35 +0200
Processing by PagesController#show as HTML
  Parameters: {"id"=>"readmef"}
  ..
  Completed 404 Not Found in 14ms (Views: 12.0ms)

所以，到目前为止，我的 :status => :not_found 是有效的。

当我做curl -v http://0.0.0.0:3000/pages/readmef卷曲日志

curl -v http://localhost:3000/pages/readmef
* About to connect() to localhost port 3000 (#0)
*   Trying 127.0.0.1...
* connected
* Connected to localhost (127.0.0.1) port 3000 (#0)
> GET /pages/readmef HTTP/1.1
> User-Agent: curl/7.24.0 (x86_64-apple-darwin12.0) libcurl/7.24.0 OpenSSL/0.9.8x zlib/1.2.5
> Host: localhost:3000
> Accept: */*
>
< HTTP/1.1 404 Not Found
< X-Frame-Options: SAMEORIGIN

但以下 RSpec 测试失败：

 it 'renders an error if page not found' do
    visit page_path('not_existing_page_321')
    expect(response.status).to eq(404)
    within( '.alert-error' ) do
      page.should have_content('Page not_existing_page_321 doesn\'t exist')
    end
  end

  1) PagesController renders an error if page not found
     Failure/Error: expect(response.status).to eq(404)

       expected: 404
            got: 200

一切看起来都很好，甚至 test.log 也显示 404

$ tail -f log/test.log
Started GET "/pages/not_existing_page_321" for 127.0.0.1 at 2013-08-03 09:48:13 +0200
Processing by PagesController#show as HTML
  Parameters: {"id"=>"not_existing_page_321"}
  Rendered pages/_page.haml (0.8ms)
  Rendered layouts/_navigation.haml (0.6ms)
  Rendered layouts/_messages.haml (0.2ms)
  Rendered layouts/_locales.haml (0.3ms)
  Rendered layouts/_footer.haml (0.6ms)
Completed 404 Not Found in 6ms (Views: 4.5ms)

我尝试了不同的服务器，WebRICK、Thin、unicorn。在开发和生产模式下一切都按预期进行。即使 test.log 是正确的，但测试失败。

谁能告诉我为什么测试显示 200 而不是 404？

RSpec 3+ 的另一种方法是测试异常：

it 'responds with a 404 if the page is not found' do
  expect { get(:show, id: 'bad_id') }.to raise_error(ActionController::RoutingError)
end