Selenium::WebDriver::Error::UnknownError: 无效的内容类型

Question

In my Ruby on Rails 5 app I have the following test that started failing without any changes to the code:

require 'rails_helper'

RSpec.describe 'Agent Groups Index Page' do
  let(:active_user) {FactoryBot.create(:agent)}
  let(:user_group) {FactoryBot.create(:group, servicing_agent_id: active_user.id)}
  let(:other_user) {FactoryBot.create(:agent, :other_agent)}
  let(:other_group) {FactoryBot.create(:group, servicing_agent_id: other_user.id)}
  let(:zip_code) {FactoryBot.create(:zip_code)}

  before do
    visit new_user_session_path
    fill_in 'user_email', with: active_user.email
    fill_in 'user_password', with: active_user.password
    click_button 'Login'
  end

  context 'has no groups' do
    before do
      other_user
      other_group
      visit groups_path()
    end

    scenario 'sees empty list', js: true do
      expect(page).to have_content 'No data available in table'
    end
  end
end

it returns the following error:

Failure/Error: click_button 'Login'
 Selenium::WebDriver::Error::UnknownError:
   Invalid Content-Type
 # /Users/override23/.rvm/gems/ruby-2.5.1@-global/gems/selenium-webdriver-3.11.0/lib/selenium/webdriver/remote/response.rb:69:in `assert_ok'
 # /Users/override23/.rvm/gems/ruby-2.5.1@-global/gems/selenium-webdriver-3.11.0/lib/selenium/webdriver/remote/response.rb:32:in `initialize'
 # /Users/override23/.rvm/gems/ruby-2.5.1@-global/gems/selenium-webdriver-3.11.0/lib/selenium/webdriver/remote/http/common.rb:81:in `new'
 # /Users/override23/.rvm/gems/ruby-2.5.1@-global/gems/selenium-webdriver-3.11.0/lib/selenium/webdriver/remote/http/common.rb:81:in `create_response'
 # /Users/override23/.rvm/gems/ruby-2.5.1@-global/gems/selenium-webdriver-3.11.0/lib/selenium/webdriver/remote/http/default.rb:104:in `request'
 # /Users/override23/.rvm/gems/ruby-2.5.1@-global/gems/selenium-webdriver-3.11.0/lib/selenium/webdriver/remote/http/common.rb:59:in `call'
 # /Users/override23/.rvm/gems/ruby-2.5.1@-global/gems/selenium-webdriver-3.11.0/lib/selenium/webdriver/remote/bridge.rb:164:in `execute'
 # /Users/override23/.rvm/gems/ruby-2.5.1@-global/gems/selenium-webdriver-3.11.0/lib/selenium/webdriver/remote/w3c/bridge.rb:535:in `execute'
 # /Users/override23/.rvm/gems/ruby-2.5.1@-global/gems/selenium-webdriver-3.11.0/lib/selenium/webdriver/remote/w3c/bridge.rb:358:in `click_element'
 # /Users/override23/.rvm/gems/ruby-2.5.1@-global/gems/selenium-webdriver-3.11.0/lib/selenium/webdriver/common/element.rb:72:in `click'
 # /Users/override23/.rvm/gems/ruby-2.5.1@-global/gems/capybara-3.0.2/lib/capybara/selenium/node.rb:94:in `click'
 # /Users/override23/.rvm/gems/ruby-2.5.1@-global/gems/capybara-3.0.2/lib/capybara/node/element.rb:133:in `block in click'
 # /Users/override23/.rvm/gems/ruby-2.5.1@-global/gems/capybara-3.0.2/lib/capybara/node/base.rb:83:in `synchronize'
 # /Users/override23/.rvm/gems/ruby-2.5.1@-global/gems/capybara-3.0.2/lib/capybara/node/element.rb:133:in `click'
 # /Users/override23/.rvm/gems/ruby-2.5.1@-global/gems/capybara-3.0.2/lib/capybara/node/actions.rb:58:in `click_button'
 # /Users/override23/.rvm/gems/ruby-2.5.1@-global/gems/capybara-3.0.2/lib/capybara/session.rb:740:in `block (2 levels) in <class:Session>'
 # /Users/override23/.rvm/gems/ruby-2.5.1@-global/gems/capybara-3.0.2/lib/capybara/dsl.rb:51:in `block (2 levels) in <module:DSL>'
 # ./spec/support/helpers/session_helpers.rb:7:in `signin'
 # ./spec/features/agents/groups/groups_index_spec.rb:11:in `block (2 levels) in <top (required)>'

Any ideas what can cause this strange behavior?

Answer 1

I had the same problem with our Docker-based CI setup. I was able to fix it by specifying the version of the Selenium image that Capybara talks to.

So in the docker-compose.yml our configuration went from:

  firefox:
    image: selenium/standalone-firefox
    volumes:
      - /dev/shm:/dev/shm

To:

  firefox:
    image: selenium/standalone-firefox:3.11
    volumes:
      - /dev/shm:/dev/shm

In addition to the above, we specified the versions of capybara and selenium-webdriver in the Gemfile for this project to give us certainty about compatibility. We will upgrade them all in lockstep in the future, but this is a good way to keep things working in the meantime.