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Headless

A class incapsulating the creation and usage of a headless X server

Prerequisites

Usage

Block mode:

require 'rubygems'
require 'headless'
require 'selenium-webdriver'

Headless.ly do
  driver = Selenium::WebDriver.for :firefox
  driver.navigate.to 'http://google.com'
  puts driver.title
end

Object mode:

require 'rubygems'
require 'headless'
require 'selenium-webdriver'

headless = Headless.new
headless.start

driver = Selenium::WebDriver.for :firefox
driver.navigate.to 'http://google.com'
puts driver.title

headless.destroy

Attributes

dimensions[R]

The display dimensions

display[R]

The display number

Public Class Methods

ly(options={}, &block) click to toggle source
Alias for: run
new(options = {}) click to toggle source

Creates a new headless server, but does NOT switch to it immediately. Call start for that

List of available options:

  • display (default 99) - what display number to listen to;

  • reuse (default true) - if given display server already exists, should we use it or try another?

  • autopick (default true is display number isn't explicitly set) - if Headless should automatically pick a display, or fail if the given one is not available.

  • dimensions (default 1280x1024x24) - display dimensions and depth. Not all combinations are possible, refer to +man Xvfb+.

  • destroy_at_exit (default true) - if a display is started but not stopped, should it be destroyed when the script finishes?

# File lib/headless.rb, line 65
def initialize(options = {})
  CliUtil.ensure_application_exists!('Xvfb', 'Xvfb not found on your system')

  @display = options.fetch(:display, DEFAULT_DISPLAY_NUMBER).to_i
  @autopick_display = options.fetch(:autopick, !options.key?(:display))
  @reuse_display = options.fetch(:reuse, true)
  @dimensions = options.fetch(:dimensions, DEFAULT_DISPLAY_DIMENSIONS)
  @video_capture_options = options.fetch(:video, {})
  @destroy_at_exit = options.fetch(:destroy_at_exit, true)

  attach_xvfb
end
run(options={}, &block) click to toggle source

Block syntax:

Headless.run do
  # perform operations in headless mode
end

See new for options

# File lib/headless.rb, line 102
def self.run(options={}, &block)
  headless = Headless.new(options)
  headless.start
  yield headless
ensure
  headless.destroy
end
Also aliased as: ly

Public Instance Methods

destroy() click to toggle source

Switches back from the headless server and terminates the headless session

# File lib/headless.rb, line 91
def destroy
  stop
  CliUtil.kill_process(pid_filename)
end
start() click to toggle source

Switches to the headless server

# File lib/headless.rb, line 79
def start
  @old_display = ENV['DISPLAY']
  ENV['DISPLAY'] = ":#{display}"
  hook_at_exit
end
stop() click to toggle source

Switches back from the headless server

# File lib/headless.rb, line 86
def stop
  ENV['DISPLAY'] = @old_display
end
take_screenshot(file_path) click to toggle source 
# File lib/headless.rb, line 115
def take_screenshot(file_path)
  CliUtil.ensure_application_exists!('import', "imagemagick not found on your system. Please install it using sudo apt-get install imagemagick")

  system "#{CliUtil.path_to('import')} -display localhost:#{display} -window root #{file_path}"
end
video() click to toggle source 
# File lib/headless.rb, line 111
def video
  @video_recorder ||= VideoRecorder.new(display, dimensions, @video_capture_options)
end

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