Checking Jquery Ajax requests from Capybara

I was working in a particular feature today. I wanted to test an autocomplete input box that makes its requests via Ajax. Something very common.

I wanted to test that the requests were being done to the right URL in a black box kind of way using the cucumber features.

This is what I did:

• First added a new visit method visit_tracking_ajax to my Cucumber environment with the following content

  module CucumberGlobals
   def visit_tracking_ajax(url)
    visit(url)
    page.execute_script("$(document).ajaxSuccess(function(a,b,c){console.log(this);window._latest_ajax_url_called = c.url;})")
   end
  end
  
  World(CucumberGlobals)
  

This executes a Javascript Jquery script in the page that will listen to every Ajax request being made (through Jquery) and set a variable on window with the URL called in that request.

• Then from my step definition I did something like:

  page.latest_ajax_url.should == 'http://www.xx.xxx'
  

• Having also added the following method to the Capybara session:

  module CustomMethods
   def latest_ajax_url
     evaluate_script("window._latest_ajax_url_called")
   end
  end
  
  module Capybara
    class Session
      include CustomMethods
    end
  end
  

That's it, now I was checking the last ajax url being called. This is fragile code, but it worked fine for my current use case.