Poltergeist - A PhantomJS driver for Capybara
poltergeist to your Gemfile, and add in your test setup add:
Currently PhantomJS is not 'truly headless', so to run it on a continuous integration
server you will need to use Xvfb. You can either use the
headless gem for this,
or make sure that Xvfb is running and the
DISPLAY environment variable is set.
You need PhantomJS 1.4.1+, built against Qt 4.8, on your system.
By far the easiest, most reliable thing to do is to install the pre-built static binary. Try this first.
Linux users, or if the pre-built Mac binary doesn't work
You need to build PhantomJS manually. Unfortunately, this not currently straightforward, for two reasons:
qmake --version), you'll need to build it.
A change in the version of WebKit bundled with Qt 4.8 means that in order to be able to attach files to file
<input>elements, we must apply a patch to the Qt source tree that PhantomJS is built against.
So, you basically have two options:
If you have Qt 4.8 on your system, and don't need to use file inputs, follow the standard PhantomJS build instructions.
Otherwise, download the PhantomJS tarball,
cd deploy/and run either
./build-mac.sh. The script will download Qt, apply some patches, build it, and then build PhantomJS against the patched build of Qt. It takes quite a while, around 30 minutes on a modern computer with two hyperthreaded cores. Afterwards, you should copy the
bin/phantomjsbinary into your
PhantomJS 1.5 plans to bundle a stripped-down version of Qt, which will reduce the build time a bit (although most of the time is spent building WebKit) and make it easier to apply patches. When it is possible to make static builds for Linux, those may be provided too, so most users will avoid having to build it themselves.
There are some additional features:
You can grab screenshots of the page at any point by calling
page.driver.render('/path/to/file.png') (this works the same way as the PhantomJS
render feature, so you can specify other extensions like
By default, only the viewport will be rendered (the part of the page that is in view). To render
the entire page, use
page.driver.render('/path/to/file.png', :full => true).
Resizing the window
Sometimes the window size is important to how things are rendered. Poltergeist sets the window
size to 1024x768 by default, but you can set this yourself with
You can customize the way that Capybara sets up Poltegeist via the following code in your test setup:
Capybara.register_driver :poltergeist do |app| Capybara::Poltergeist::Driver.new(app, options) end
options is a hash of options. The following options are supported:
:phantomjs(String) - A custom path to the phantomjs executable
:debug(Boolean) - When true, debug output is logged to
:logger(Object responding to
puts) - When present, debug output is written to this object
Please file bug reports on Github and include example code to reproduce the problem wherever
possible. (Tests are even better.) Please also provide the output with
:debug turned on, and screenshots if you think it's relevant.
If capybara-webkit works for you, then by all means carry on using it.
However, I have had some trouble with it, and Poltergeist basically started as an experiment to see whether a PhantomJS driver was possible. (It turned out it was, but only thanks to some new features since the 1.3 release.)
In the long term, I think having a PhantomJS driver makes sense, because that allows PhantomJS to concentrate on being an awesome headless browser, while the capybara driver (Poltergeist) is able to be the minimal amount of glue code necessary to drive the browser.
I also find it more pleasant to hack in CoffeeScript than C++, particularly as my C++ experience only goes as far as trying to make PhantomJS/Qt/WebKit work with Poltergeist :)
Contributions are very welcome and I will happily give commit access to anyone who does a few good pull requests.
To get setup, run
bundle install. You can run the full test suite with
rspec spec/ or
I previously set up the repository on Travis CI but unfortunately given they need a custom-built Qt+PhantomJS in order to pass, it can't be used for now. When static Linux PhantomJS builds are working this can be revisited.
While PhantomJS is capable of compiling and running CoffeeScript code
directly, I prefer to compile the code myself and distribute that (it
makes debugging easier). Running
rake autocompile will watch the
.coffee files for changes, and compile them into
Copyright (c) 2011 Jonathan Leighton
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