Jon Leighton

Poltergeist: A PhantomJS driver for Capybara

This announcement is coming way later than I had originally intended. Last October I started experimenting with the idea of writing a driver for Capybara that would use PhantomJS as the browser.

Initially the biggest problem was addressing the issue of how to communicate between a Ruby process and a PhantomJS process. But then it hit me: PhantomJS gives you a browser environment, so you can do everything you can do in a browser, and you can do Web Sockets in a browser. So I used Web Sockets.

After hacking away for a while I eventually had a pretty complete driver. But I was being plagued by segfaults that were coming from WebKit’s JavaScriptCore JS engine. Thus began months of poking C++ code and getting far too comfortable with gdb.

I tried the Qt 4.8 RC (it has since been properly released) and found that the JSC segfault had gone, but now there was a new segfault. After much hair-pulling I found a workaround. But I was still left with another problem: it wasn’t possible to attach files to <input> elements against Qt 4.8. After yet more hair-pulling I found the culprit for that one, too.

Which leads me to the point where I am now finally happy to invite you, dear reader, to try out my humble little Capybara driver. Let me know how you get on!

3 January 2012