Selenium Webdriver - set preferred browser language DE - ruby

Question

I have a problem setting the preferred (accepted language) within headless Chrome using Selenium Webdriver and Ruby. I use the following WebDriver settings:
Selenium::WebDriver::Chrome.driver_path = #config[<path to the Chrome Driver>]
options = Selenium::WebDriver::Chrome::Options.new
options.add_argument('--headless')
options.add_argument('--disable-translate')
options.add_argument("--lang=de")
The driver is then initialized with:
#selenium_driver = Selenium::WebDriver.for :chrome, options: options
Everything works fine but at some pages Chrome returns English content even when I navigate to the German page URL (e.g. page.de). In these cases the Chrome driver returns the English content due to an internal forwarding to page.de/en. I do not specify the en path in my queried URL.
I have tried to set the language using the Webdriver preference:
options.add_preference('accept_languages', 'de')
instead of the add_argument but it doesn't change anything of the behavior.
Does anyone have an idea how to force a headless Chrome controlled by Selenium Webdriver within Ruby to request page content in a defined language or - not optimal but it might help as a workaround - to stop the forwarding?
Any help greatly appreciated
Best
Krid

Answer 1

I found a solution that works for me. As in many cases the problem was sitting in front of the screen and simply doesn't work precisely enough ;-)
Instead of using
options.add_argument("--lang=de")
you have to use
options.add_argument("--lang=de-DE")
When I use an IETF language tag the code I initially posted works as expected.

Answer 2

I'am using this in my test_helper.rb Works fine for me.
Capybara.register_driver :selenium do |app|
Chromedriver.set_version "2.36"
desired_capabilities = Selenium::WebDriver::Remote::Capabilities.chrome(
'chromeOptions' => {
'prefs' => {
'intl.accept_languages' => 'en-US'
},
args: ['disable-gpu', 'headless']
}
)
Capybara::Selenium::Driver.new(app, { browser: :chrome, desired_capabilities: desired_capabilities })
end
Capybara.javascript_driver = :chrome
Capybara.default_driver = :selenium

Answer 3

This prefs hash inside an options hash did the trick for me. It's at the end of the driven_by :selenium line.
(Inside test/application_syste_test_case.rb)
# frozen_string_literal: true
require 'test_helper'
require 'capybara/rails'
class ApplicationSystemTestCase < ActionDispatch::SystemTestCase
driven_by :selenium, using: :chrome, screen_size: [1400, 1400], options: { prefs: { 'intl.accept_languages' => 'de,de-DE;q=0.9,en;q=0.1' } }
# ...
2021-06-14 UPDATE:
The previous example produces this deprecation warning:
WARN Selenium [DEPRECATION] :prefs is deprecated. Use Selenium::WebDriver::Chrome::Options#add_preference instead.
IMO, the solution below is uglier, but I'm posting it for when it's fully deprecated and the original stops working.
class ApplicationSystemTestCase < ActionDispatch::SystemTestCase
driven_by(:selenium,
using: :chrome,
screen_size: [1400, 1400],
options: {
options: Selenium::WebDriver::Chrome::Options.new(
prefs: { 'intl.accept_languages' => 'de,de-DE;q=0.9,en;q=0.1' }
)
},
)

Answer 4

You should be able to solve your problem by adding an experimental option:
options.add_option('prefs', {'intl.accept_languages': 'en,en_US'})
I'm sure it works with Python, but I've not tried with Ruby: this approach is the correct one, not sure about the implementation.
You can find in this repository the code which handles your problem in Python code, and in this Q&A how to implement experimental_options in Ruby

Answer 5

For me works:
options = Selenium::WebDriver::Firefox::Options.new
options.add_preference("intl.accept_languages", 'de-DE')
Capybara::Selenium::Driver.new(app, browser: :firefox, options: options)