support headless configuration for Firefox in selenium-webdriver package

[mykmelez]

OS: Windows, macOS, Linux
Selenium Version: 3.5.0
Browser: Firefox
Browser Version: 56

Once Firefox supports headless mode on all three platforms (starting with Firefox 56, currently in beta and due to be released next month), the selenium-webdriver package should support configuring Firefox to run headlessly the same way it supports Chrome running headlessly, via a headless() method on the Firefox driver's Options class, so that you can drive Firefox headlessly via:

const { Builder } = require('selenium-webdriver');
const firefox = require('selenium-webdriver/firefox');
const driver = new Builder()
.forBrowser('firefox')
.setFirefoxOptions(new firefox.Options().headless())
.build();

(It would additionally be useful to be able to set the headless window's size via the equivalent of Chrome's windowSize({width, height}) method.)

[barancev]

This option should be added to all language binding.

[barancev]

Implemented in Java binding by 38a5130

[franzliedke]

As far as I can tell, this is already possible with the Ruby bindings:

options = Selenium::WebDriver::Firefox::Options.new(
  args: ['-headless']
)

Selenium::WebDriver.for :firefox, options: options

[lmtierney]

@franzliedke yes it is most likely possible with all bindings, but this is asking for a shortcut without having to specify it in args

[mykmelez]

Right, note that Chrome already supports this configuration in selenium-webdriver:

selenium/javascript/node/selenium-webdriver/chrome.js

Lines 39 to 51 in 18660c4

	* __Headless Chrome__ <a id="headless"></a>
	*
	* To start Chrome in headless mode, simply call
	* {@linkplain Options#headless Options.headless()}. Note, starting in headless
	* mode currently also disables GPU acceleration.
	*
	* let chrome = require('selenium-webdriver/chrome');
	* let {Builder} = require('selenium-webdriver');
	*
	* let driver = new Builder()
	* .forBrowser('chrome')
	* .setChromeOptions(new chrome.Options().headless())
	* .build();

And selenium-webdriver also provides an example script using it:

https://github.com/SeleniumHQ/selenium/blob/master/javascript/node/selenium-webdriver/example/chrome_headless.js

Although strangely the docs don't mention it:

http://seleniumhq.github.io/selenium/docs/api/javascript/module/selenium-webdriver/chrome_exports_Options.html

This issue is about doing the same for Firefox. It may be merely syntactic sugar, but it's useful nonetheless.

[franzliedke]

Thanks for clarification. I sent a PR for the Ruby bindings: #4762.