Merge branch 'dz-spinach-wait-ajax' into 'master'

Wait for ajax for every merge request spinach test

## What does this MR do?

* removes duplicate `WaitForAjax` module
* ensure we run `wait_for_ajax`after each MR spinach tests

## Why was this MR needed?

Because when visit MR page we do ajax call to check CI status. When testing this page with spinach and JS driver we got random failing tests. It happens because of race condition db cleaner drop data before ajax call finished. So we make sure that every MR spinach scenario with js driver waits for ajax before running next scenario

## What are the relevant issue numbers?

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/23461

See merge request !6959

features/steps/project/merge_requests.rb

@@ -9,6 +9,10 @@ class Spinach::Features::ProjectMergeRequests < Spinach::FeatureSteps
   include SharedUser
   include WaitForAjax
 
+  after do
+    wait_for_ajax if javascript_test?
+  end
+
   step 'I click link "New Merge Request"' do
     click_link "New Merge Request"
   end

features/steps/shared/note.rb

-require Rails.root.join('features/support/wait_for_ajax')
-
 module SharedNote
   include Spinach::DSL
   include WaitForAjax

features/support/env.rb

@@ -15,7 +15,7 @@ if ENV['CI']
   Knapsack::Adapters::SpinachAdapter.bind
 end
 
-%w(select2_helper test_env repo_helpers).each do |f|
+%w(select2_helper test_env repo_helpers wait_for_ajax).each do |f|
   require Rails.root.join('spec', 'support', f)
 end
 

features/support/wait_for_ajax.rb

-module WaitForAjax
-  def wait_for_ajax
-    Timeout.timeout(Capybara.default_max_wait_time) do
-      loop until finished_all_ajax_requests?
-    end
-  end
-
-  def finished_all_ajax_requests?
-    page.evaluate_script('jQuery.active').zero?
-  end
-end

spec/support/wait_for_ajax.rb

@@ -8,4 +8,8 @@ module WaitForAjax
   def finished_all_ajax_requests?
     page.evaluate_script('jQuery.active').zero?
   end
+
+  def javascript_test?
+    [:selenium, :webkit, :chrome, :poltergeist].include?(Capybara.current_driver)
+  end
 end