Poltergeist is a driver for Capybara. It allows you to run your Capybara tests on a headless WebKit browser, provided by PhantomJS.
If you're viewing this at https://github.com/jonleighton/poltergeist, you're reading the documentation for the master branch. View documentation for the latest release (1.4.1).
Questions should be posted on Stack Overflow, using the 'poltergeist' tag.
Bug reports should be posted on GitHub (and be sure to read the bug reporting guidance below).
Add poltergeist
to your Gemfile, and in your test setup add:
require 'capybara/poltergeist'
Capybara.javascript_driver = :poltergeist
If you were previously using the :rack_test
driver, be aware that
your app will now run in a separate thread and this can have
consequences for transactional tests. See the Capybara README for more
detail.
You need at least PhantomJS 1.8.1. There are no other external dependencies (you don't need Qt, or a running X server, etc.)
- Homebrew:
brew install phantomjs
- MacPorts:
sudo port install phantomjs
- Manual install: Download this
- Download the precompiled binary for Windows
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
./build.sh
(See also the PhantomJS building guide.)
Poltergeist runs on MRI 1.9, JRuby 1.9 and Rubinius 1.9. Poltergeist and PhantomJS are currently supported on Mac OS X, Linux, and Windows platforms.
Ruby 1.8 is no longer supported. The last release to support Ruby 1.8 was 1.0.2, so you should use that if you still need Ruby 1.8 support.
There are no special steps to take. You don't need Xvfb or any running X server at all.
Travis CI has PhantomJS pre-installed, but it might not be the latest version. If you need to install the latest version, check out the .travis.yml that Poltergeist uses.
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.
Poltergeist supports all the mandatory features for a Capybara driver, and the following optional features:
page.evaluate_script
andpage.execute_script
page.within_frame
page.within_window
page.status_code
page.response_headers
page.save_screenshot
page.render_base64
page.scroll_to
- cookie handling
- drag-and-drop
There are some additional features:
You can grab screenshots of the page at any point by calling
save_screenshot('/path/to/file.png')
(this works the same way as the PhantomJS
render feature, so you can specify other extensions like .pdf
, .gif
, etc.)
By default, only the viewport will be rendered (the part of the page that is in view). To render
the entire page, use save_screenshot('/path/to/file.png', :full => true)
.
You also have an ability to render selected element. Pass option selector
with
any valid element selector to make a screenshot bounded by that element
save_screenshot('/path/to/file.png', :selector => '#id')
.
If you need for some reasons base64 encoded screenshot you can simply call
render_base64
that will return you encoded image. Additional options are the
same as for save_screenshot
except the first argument which is format (:png by
default, acceptable :png, :gif, :jpeg).
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 page.driver.resize(width, height)
.
Sometimes its desirable to click a very specific area of the screen. You can accomplish this with
page.driver.click(x, y)
, where x and y are the screen coordinates.
If you use the :inspector => true
option (see below), remote debugging
will be enabled.
When this option is enabled, you can insert page.driver.debug
into
your tests to pause the test and launch a browser which gives you the
WebKit inspector to view your test run with.
You can register this debugger driver with a different name and set it as the current javascript driver. By example, in your helper file:
Capybara.register_driver :poltergeist_debug do |app|
Capybara::Poltergeist::Driver.new(app, :inspector => true)
end
# Capybara.javascript_driver = :poltergeist
Capybara.javascript_driver = :poltergeist_debug
You can manipulate HTTP request headers with these methods:
page.driver.headers # => {}
page.driver.headers = { "User-Agent" => "Poltergeist" }
page.driver.add_headers("Referer" => "https://example.com")
page.driver.headers # => { "User-Agent" => "Poltergeist", "Referer" => "https://example.com" }
Notice that headers=
will overwrite already set headers. You should use
add_headers
if you want to add a few more. These headers will apply to all
subsequent HTTP requests (including requests for assets, AJAX, etc). They will
be automatically cleared at the end of the test. You have ability to set headers
only for the initial request:
page.driver.headers = { "User-Agent" => "Poltergeist" }
page.driver.add_header("Referer", "http://example.com", permanent: false)
page.driver.headers # => { "User-Agent" => "Poltergeist", "Referer" => "http://example.com" }
visit(login_path)
page.driver.headers # => { "User-Agent" => "Poltergeist" }
This way your temporary headers will be sent only for the initial request, all subsequent request will only contain your permanent headers.
You can inspect the network traffic (i.e. what resources have been
loaded) on the current page by calling page.driver.network_traffic
.
This returns an array of request objects. A request object has a
response_parts
method containing data about the response chunks.
The following methods are used to inspect and manipulate cookies:
page.driver.cookies
- a hash of cookies accessible to the current page. The keys are cookie names. The values areCookie
objects, with the following methods:name
,value
,domain
,path
,secure?
,httponly?
,expires
.page.driver.set_cookie(name, value, options = {})
- set a cookie. The options hash can take the following keys::domain
,:path
,:secure
,:httponly
,:expires
.:expires
should be aTime
object.page.driver.remove_cookie(name)
- remove a cookie
The following methods can be used to execute commands inside different windows:
-
page.driver.window_handles
- an array containing the names of all the open windows. -
page.within_window(name) { # actions }
- executes the passed block in the context of the named window.
Example:
find_link("Login with Facebook").trigger("click")
sleep(0.1)
fb_popup = page.driver.window_handles.last
page.within_window fb_popup do
fill_in "email", :with => "[email protected]"
fill_in "pass", :with => "my_pass"
click_button "Log In"
end
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 toSTDERR
. Some debug info from the PhantomJS portion of Poltergeist is also output, but this goes toSTDOUT
due to technical limitations.:logger
(Object responding toputs
) - When present, debug output is written to this object:phantomjs_logger
(IO
object) - Where theSTDOUT
from PhantomJS is written to. This is where yourconsole.log
statements will show up. Default:STDOUT
:timeout
(Numeric) - The number of seconds we'll wait for a response when communicating with PhantomJS. Default is 30.:inspector
(Boolean, String) - See 'Remote Debugging', above.:js_errors
(Boolean) - When false, Javascript errors do not get re-raised in Ruby.:window_size
(Array) - The dimensions of the browser window in which to test, expressed as a 2-element array, e.g. [1024, 768]. Default: [1024, 768]:phantomjs_options
(Array) - Additional command line options to be passed to PhantomJS, e.g.['--load-images=no', '--ignore-ssl-errors=yes']
:extensions
(Array) - An array of JS files to be preloaded into the phantomjs browser. Useful for faking unsupported APIs.:port
(Fixnum) - The port which should be used to communicate with the PhantomJS process. Default: 44678.
Unfortunately, the nature of full-stack testing is that things can and do go wrong from time to time. This section aims to highlight a number of common problems and provide ideas about how you can work around them.
Sometimes PhantomJS crashes during a test. There are basically two kinds of crashes: those that can be reproduced every time, and those that occur sporadically and are not easily reproduced.
If your crash happens every time, you should read the PhantomJS crash reporting guide and file a bug against PhantomJS. Feel free to also file a bug against Poltergeist in case there are workarounds that can be implemented within Poltergeist. Also, if lots of Poltergeist users are experiencing the same crash then fixing it will move up the priority list.
If your crash is sporadic, there is less that can be done. Often these issues are very complicated and difficult to track down. It may be that the crash has already been fixed in a newer version of WebKit that will eventually find its way into PhantomJS. It's still worth reporting your bug against PhantomJS, but it's probably not worth filing a bug against Poltergeist as there's not much we can do.
If you experience sporadic crashes a lot, it may be worth configuring your CI to automatically re-run failing tests before reporting a failed build.
When Poltergeist clicks on an element, rather than generating a DOM click event, it actually generates a "proper" click. This is much closer to what happens when a real user clicks on the page - but it means that Poltergeist must scroll the page to where the element is, and work out the correct co-ordinates to click. If the element is covered up by another element, the click will fail (this is a good thing - because your user won't be able to click a covered up element either).
Sometimes there can be issues with this behavior. If you have problems,
it's worth taking screenshots of the page and trying to work out what's
going on. If your click is failing, but you're not getting a
MouseEventFailed
error, then you can turn on the :debug
option and look
in the output to see what co-ordinates Poltergeist is using for the
click. You can then cross-reference this with a screenshot to see if
something is obviously wrong.
If you can't figure out what's going on and just want to work around the problem so you can get on with life, consider using a DOM click event. For example, if this code is failing:
click_button "Save"
Then try:
find_button("Save").trigger('click')
Sometimes tests pass and fail sporadically. This is often because there
is some problem synchronising events properly. It's often
straightforward to verify this by adding sleep
statements into your
test to allow sufficient time for the page to settle.
If you have these types of problems, read through the Capybara documentation on asynchronous Javascript which explains the tools that Capybara provides for dealing with this.
If you run a few capybara sessions manually please make sure you've called
session.driver.quit
when you don't need session anymore. Forgetting about this
causes memory leakage and your system's resources can be exhausted earlier than
you may expect.
- Configure Poltergeist with
:debug
turned on so you can see its communication with PhantomJS. - Take screenshots to figure out what the state of your page is when the problem occurs.
- Use the remote web inspector in case it provides any useful insight
- Consider downloading the Poltergeist source and using
console.log
debugging to figure out what's going on inside PhantomJS. (This will require an understanding of the Poltergeist source code and PhantomJS, so it's only for the committed!)
If you can provide specific steps to reproduce your problem, or have specific information that might help other help you track down the problem, then please file a bug on Github.
Include as much information as possible. For example:
- Specific steps to reproduce where possible (failing tests are even better)
- The output obtained from running Poltergeist with
:debug
turned on - Screenshots
- Stack traces if there are any Ruby on Javascript exceptions generated
- The Poltergeist and PhantomJS version numbers used
- The operating system name and version used
Version history and a list of next-release features and fixes can be found in the changelog.
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.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.