spec: fix focus/blur issues, don't use buggy native events

native event/no_focus stuff is buggy (which is why it's normally not
enabled by default), so let's try a different approach...

ensure each runner has its own framebuffer (and thus its firefox should
run in the foreground). additionally, ensure the viewport has focus when
specs start so that blur/focus events fire normally.

this ensures that specs like spec/selenium/wiki_pages_spec.rb:429 pass when
run on jenkins without following another alert-accepting spec (like
spec/selenium/wiki_pages_spec:422).

test plan:
* full selenium build should pass on this commit, faster and w/ fewer
  reruns
* non-testbot test-queue selenium build should pass on dependent commit
  (running spec/selenium/wiki_pages_spec.rb w/ 5 runners concurrently)

Change-Id: Ic1bd09ab3ca8f483611201198025cdf4858d51dc
Reviewed-on: https://gerrit.instructure.com/69663
Reviewed-by: Simon Williams <simon@instructure.com>
Tested-by: Jenkins
Product-Review: Jon Jensen <jon@instructure.com>
QA-Review: Jon Jensen <jon@instructure.com>

Gemfile.d/test.rb

@@ -38,6 +38,7 @@ group :test do
   gem 'yard-appendix', '>=0.1.8'
   gem 'timecop', '0.6.3'
   gem 'jira_ref_parser', '1.0.0'
+  gem 'headless', '2.2.0', require: false
 
   unless CANVAS_RAILS4_0
     gem 'rails-dom-testing', '1.0.7'

spec/selenium/test_setup/selenium_driver_setup.rb

@@ -11,6 +11,9 @@ module SeleniumDriverSetup
       Selenium::WebDriver.const_get(browser.to_s.capitalize).path = path
     end
 
+    run_headless = ENV.key?("TEST_ENV_NUMBER")
+    set_up_display_buffer if run_headless
+
     driver = if browser == :firefox
                firefox_driver
              elsif browser == :chrome
@@ -19,11 +22,36 @@ module SeleniumDriverSetup
                ie_driver
              end
 
+    focus_viewport driver if run_headless
+
     driver.manage.timeouts.implicit_wait = 3
     driver.manage.timeouts.script_timeout = 60
+
     driver
   end
 
+  def set_up_display_buffer
+    require "headless"
+
+    test_number = ENV["TEST_ENV_NUMBER"]
+    # it'll be '', '2', '3', '4'...
+    test_number = test_number.blank? ? 1 : test_number.to_i
+    # start at 21 to avoid conflicts with other test runner Xvfb stuff
+
+    display = 20 + test_number
+    Headless.new(display: display, dimensions: "2000x2000x24").start
+    puts "Setting up DISPLAY=#{ENV['DISPLAY']}"
+  end
+
+  def focus_viewport(driver)
+    # force the viewport to have focus right away; otherwise certain specs
+    # will fail unless they follow another dialog accepting/dismissing spec,
+    # since they rely on focus/blur events, which don't fire if the window
+    # doesn't have focus
+    driver.execute_script "alert('yolo')"
+    driver.switch_to.alert.accept
+  end
+
   def ie_driver
     require 'testingbot'
     require 'testingbot/tunnel'
@@ -151,8 +179,6 @@ module SeleniumDriverSetup
 
   def firefox_profile
     profile = Selenium::WebDriver::Firefox::Profile.new
-    profile.load_no_focus_lib=(true)
-    profile.native_events = true
     profile.add_extension Rails.root.join("spec/selenium/test_setup/JSErrorCollector.xpi")
 
     if $selenium_config[:firefox_profile].present?