Capybara does not pass header after form submit

I am building a Rails 3 app which renders different views for mobile devices (using jQuery Mobile) and regular desktop browsers. I am testing with Cucumb开发者_StackOverflow中文版er/Capybara, and have separate test suites for mobile and browser. I am able to set a mobile User-Agent string in the request's HTTP header just fine using the ‘headers hack’ found here…

Using Cucumber/Capybara in Rails 3, how do I set a custom User-Agent string?

The Problem...

Most of my mobile Cucumber steps work fine (e.g., I set the mobile header in a step, thereafter the mobile views render). However after a form submit, the test then renders a browser view of the next step (not the mobile view I want). I think this may be because Capybara is dropping the header after a form submit action.

I tried to test this by adding a logger to my controller action so I could look at the user_agent headers, as follows:

def show
    # …
    logger.info("Headers: #{request.user_agent}")
    # …
end

I used an iPhone header (Buyer is the resource). In my test.log I see:

For the create action…

Started POST "/buyers" for 127.0.0.1 at 2011-04-19 16:49:18 -0700
Processing by BuyersController#create as HTML
  #...
Headers: Mozilla/5.0 (iPhone; U; CPU iPhone OS 4_0 like Mac OS X; en-us) AppleWebKit/532.9 (KHTML, like Gecko) Version/4.0.5 Mobile/8A293 Safari/6531.22.7
  #...
Redirected to http://www.example.com/buyers/1
Completed 302 Found in 7ms

For the subsequent show action (note ‘Headers:’ is blank)…

Started GET "/buyers/1" for 127.0.0.1 at 2011-04-19 16:49:18 -0700
Processing by BuyersController#show as HTML
 #...
Headers: 
 #...
Completed 200 OK in 4ms (Views: 2.8ms | ActiveRecord: 1.4ms)

As one would expect, the ‘show me the page’ step then renders the browser page, not the mobile page I want.

How can I preserve the header so all my mobile steps run in my mobile test suite?

Update

Jnicklas (creator of the truly awesome Capybara gem!) responds:

“This is more of a question than an issue, tbh. In Rack-Test there is currently there no way of achieving this short of monkey patching that I am aware of. I've been thinking about adding a header option to the rack-test driver, which would allow the passing in of different header options. If you're using a lot of JavaScript, Selenium might be a better fit anyway and allows you to set the user agent freely, IIRC.”

https://github.com/jnicklas

https://github.com/jnicklas/capybara

This feature was added to Capybara on April 25th, 2011 with this commit - https://github.com/jnicklas/capybara/commit/a00435d63085ac2e74a0f64e7b7dedc0f7252ea9

You can can now specify a custom header when using a custom Capybara driver. See http://automagical.posterous.com/creating-a-custom-capybara-driver for code examples.

Here's how we fixed it, to work with javascript as well (note, use remove_headers in your After block):

module CapybaraHeadersHelper
  def add_headers(headers)
    headers.each do |name, value|
      case page.driver.class.to_s
      when "Capybara::RackTest::Driver"
        page.driver.options[:headers] ||= {}
        page.driver.options[:headers][name.to_s] = value

      when "Capybara::Driver::Webkit"
        page.driver.browser.header name, value

      end
    end
  end

  def remove_headers(headers)
    headers.each do |name|
      case page.driver.class.to_s
      when "Capybara::RackTest::Driver"
        page.driver.options[:headers] ||= {}
        page.driver.options[:headers].delete name.to_s

      when "Capybara::Driver::Webkit"
        page.driver.browser.header name, nil

      end
    end
  end
end

World(CapybaraHeadersHelper)