Configure Capybara to use Marionette WebDriver for Firefox
marionette is passed an option to Driver.new - not to desired_capabilities
Capybara.register_driver :selenium_firefox do |app| Capybara::Selenium::Driver.new(app, browser: :firefox, marionette: true)endIt also requires you to have downloaded geckodriver, put it in your path and renamed it to wires
A complete description of these configuration steps, including Marionette latest executables download links can be found here.
Note: Capybara does not yet support marionette, some things are being fixed in capybara, some are bugs in selenium-webdriver, and others are just general flakiness of it - things like it just stops selecting options from select elements - no errors thrown, just stops working. I don't think its ready for real world use yet.