Poltergeist - A PhantomJS driver for Capybara
poltergeist to your Gemfile, and in your test setup add:
Important note about Rack versions < 1.3.0
Prior to version 1.3.0, the Rack handlers for Mongrel and Thin wrap your
app in the
Rack::Chunked middleware so that it uses
This has been observed to cause problems,
probably due to race conditions in Qt's HTTP handling code, so you are
recommended to avoid this by specifying your own server setup for
Capybara.server do |app, port| require 'rack/handler/thin' Thin::Logging.silent = true Thin::Server.new('0.0.0.0', port, app).start end
If you're using Rails 3.0, this affects you. If you're using Rails 3.1+, this doesn't affect you.
You need PhantomJS 1.5.0. There are no other dependencies (you don't need Qt, or Xvfb, etc.)
- With homebrew:
brew install phantomjs
- Without homebrew: Download this
- Download the 32 bit or 64 bit binary.
- Extract it:
sudo tar xvzf phantomjs-1.5.0-linux-*-dynamic.tar.gz -C /usr/local
- Link it:
sudo ln -s /usr/local/phantomjs/bin/phantomjs /usr/local/bin/phantomjs
(Note that you cannot copy the
binary elsewhere on its own as it dynamically links with other files in
Do this as a last resort if the binaries don't work for you. It will take quite a long time as it has to build WebKit.
- Download the source tarball
- Extract and cd in
Supported: MRI 1.8.7, MRI 1.9.2, MRI 1.9.3, JRuby 1.8, JRuby 1.9.
- Rubinius (due to some unknown socket related issues)
Contributions are welcome in order to move 'unsupported' items into the 'supported' list.
Running on a CI
There are no special steps to take. You don't need Xvfb or any running X server at all.
Depending on your tests, one thing that you may need is some fonts. If you're getting errors on a CI that don't occur during development then try taking some screenshots - it may well be missing fonts throwing things off kilter. Your distro will have various font packages available to install.
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
Remote debugging (experimental)
If you use the
:inspector => true option (see below), remote debugging
will be enabled.
When this option is enabled, you can insert
your tests to pause the test and launch a browser which gives you the
WebKit inspector to view your test run with.
(This feature is considered experimental - it needs more polish and apparently will only work on Linux.)
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
:timeout(Numeric) - The number of seconds we'll wait for a response when communicating with PhantomJS.
nilmeans wait forever. Default is 30.
:inspector(Boolean, String) - See 'Remote Debugging', above.
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.
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
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
Detect if clicking an element will fail. If the click will actually hit another element (because that element is in front of the one we want to click), the user will now see an exception explaining what happened and which element would actually be targeted by the click. This should aid debugging. [Issue #25]
Click elements at their middle position rather than the top-left. This is presumed to be more likely to succeed because the top-left may be obscured by overlapping elements, negative margins, etc. [Issue #26]
Add experimental support for using the remote WebKit web inspector. This will only work with PhantomJS 1.5, which is not yet released, so it won't be officially supported by Poltergeist until 1.5 is released. [Issue #31]
page.driver.quitmethod. If you spawn additional Capybara sessions, you might want to use this to reap the child phantomjs process. [Issue #24]
JRuby support. [Issue #20]
Fix bug where we could end up interacting with an obsolete element. [Issue #30]
Raise an suitable error if PhantomJS returns a non-zero exit status. Previously a version error would be raised, indicating that the PhantomJS version was too old when in fact it did not start at all. [Issue #23]
:timeoutoption is actually used. [Issue #36]
In some circumstances, we could end up missing an inline element when attempting to click it. This is due to the use of
getBoundingClientRect(). We're now using
getClientRects()to address this.
Element click position is now calculated using the native
getBoundingClientRect()method, which will be faster and less buggy.
window.confirm(). Always returns true, which is the same as capybara-webkit. [Issue #10]
window.prompt(). Returns the default value, if present, or null.
There was a bad bug to do with clicking elements in a page where the page is smaller than the window. The incorrect position would be calculated, and so the click would happen in the wrong place. This is fixed. [Issue #8]
Poltergeist didn't work in conjunction with the Thin web server, because that server uses Event Machine, and Poltergeist was assuming that it was the only thing in the process using EventMachine.
To solve this, EventMachine usage has been completely removed, which has the welcome side-effect of being more efficient because we no longer have the overhead of running a mostly-idle event loop.
:timeoutoption to configure the timeout when talking to PhantomJS.
- First version considered 'ready', hopefully fewer problems.
- First version, various problems.
Copyright (c) 2011 Jonathan Leighton
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
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