Merge branch '28307-fix-sporadic-feature-spec-failures' into 'master'

Introduce a new middleware for the test environment that can block requests

Closes #28307

See merge request !9846

Gemfile

@@ -327,6 +327,7 @@ group :test do
   gem 'test_after_commit', '~> 1.1'
   gem 'sham_rack', '~> 1.3.6'
   gem 'timecop', '~> 0.8.0'
+  gem 'concurrent-ruby', '~> 1.0.5'
 end
 
 gem 'octokit', '~> 4.6.2'

Gemfile.lock

@@ -128,7 +128,7 @@ GEM
       execjs
     coffee-script-source (1.10.0)
     colorize (0.7.7)
-    concurrent-ruby (1.0.4)
+    concurrent-ruby (1.0.5)
     connection_pool (2.2.1)
     crack (0.4.3)
       safe_yaml (~> 1.0.0)
@@ -868,6 +868,7 @@ DEPENDENCIES
   chronic (~> 0.10.2)
   chronic_duration (~> 0.10.6)
   coffee-rails (~> 4.1.0)
+  concurrent-ruby (~> 1.0.5)
   connection_pool (~> 2.0)
   creole (~> 0.5.0)
   d3_rails (~> 3.5.0)

config/environments/test.rb

 Rails.application.configure do
+  # Make sure the middleware is inserted first in middleware chain
+  config.middleware.insert_before('ActionDispatch::Static', 'Gitlab::Testing::RequestBlockerMiddleware')
+
   # Settings specified here will take precedence over those in config/application.rb
 
   # The test environment is used exclusively to run your application's

lib/gitlab/testing/request_blocker_middleware.rb

+# rubocop:disable Style/ClassVars
+
+# This is inspired by http://www.salsify.com/blog/engineering/tearing-capybara-ajax-tests
+# Rack middleware that keeps track of the number of active requests and can block new requests.
+module Gitlab
+  module Testing
+    class RequestBlockerMiddleware
+      @@num_active_requests = Concurrent::AtomicFixnum.new(0)
+      @@block_requests = Concurrent::AtomicBoolean.new(false)
+
+      # Returns the number of requests the server is currently processing.
+      def self.num_active_requests
+        @@num_active_requests.value
+      end
+
+      # Prevents the server from accepting new requests. Any new requests will return an HTTP
+      # 503 status.
+      def self.block_requests!
+        @@block_requests.value = true
+      end
+
+      # Allows the server to accept requests again.
+      def self.allow_requests!
+        @@block_requests.value = false
+      end
+
+      def initialize(app)
+        @app = app
+      end
+
+      def call(env)
+        increment_active_requests
+        if block_requests?
+          block_request(env)
+        else
+          @app.call(env)
+        end
+      ensure
+        decrement_active_requests
+      end
+
+      private
+
+      def block_requests?
+        @@block_requests.true?
+      end
+
+      def block_request(env)
+        [503, {}, []]
+      end
+
+      def increment_active_requests
+        @@num_active_requests.increment
+      end
+
+      def decrement_active_requests
+        @@num_active_requests.decrement
+      end
+    end
+  end
+end

spec/features/participants_autocomplete_spec.rb

 require 'spec_helper'
 
-feature 'Member autocomplete', feature: true do
-  include WaitForAjax
-
+feature 'Member autocomplete', :js do
   let(:project) { create(:project, :public) }
   let(:user) { create(:user) }
-  let(:participant) { create(:user) }
   let(:author) { create(:user) }
+  let(:note) { create(:note, noteable: noteable, project: noteable.project) }
 
   before do
-    allow_any_instance_of(Commit).to receive(:author).and_return(author)
-    login_as user
+    note # actually create the note
+    login_as(user)
   end
 
-  shared_examples "open suggestions" do
-    it 'displays suggestions' do
-      expect(page).to have_selector('.atwho-view', visible: true)
-    end
-
-    it 'suggests author' do
-      page.within('.atwho-view', visible: true) do
-        expect(page).to have_content(author.username)
+  shared_examples "open suggestions when typing @" do
+    before do
+      page.within('.new-note') do
+        find('#note_note').send_keys('@')
       end
     end
 
-    it 'suggests participant' do
+    it 'suggests noteable author and note author' do
       page.within('.atwho-view', visible: true) do
-        expect(page).to have_content(participant.username)
+        expect(page).to have_content(author.username)
+        expect(page).to have_content(note.author.username)
       end
     end
   end
 
-  context 'adding a new note on a Issue', js: true do
+  context 'adding a new note on a Issue' do
+    let(:noteable) { create(:issue, author: author, project: project) }
     before do
-      issue = create(:issue, author: author, project: project)
-      create(:note, note: 'Ultralight Beam', noteable: issue,
-                    project: project, author: participant)
-      visit_issue(project, issue)
+      visit namespace_project_issue_path(project.namespace, project, noteable)
     end
 
-    context 'when typing @' do
-      include_examples "open suggestions"
-      before do
-        open_member_suggestions
-      end
-    end
+    include_examples "open suggestions when typing @"
   end
 
-  context 'adding a new note on a Merge Request ', js: true do
+  context 'adding a new note on a Merge Request' do
+    let(:noteable) do
+      create(:merge_request, source_project: project,
+                             target_project: project, author: author)
+    end
     before do
-      merge = create(:merge_request, source_project: project, target_project: project, author: author)
-      create(:note, note: 'Ultralight Beam', noteable: merge,
-                    project: project, author: participant)
-      visit_merge_request(project, merge)
+      visit namespace_project_merge_request_path(project.namespace, project, noteable)
     end
 
-    context 'when typing @' do
-      include_examples "open suggestions"
-      before do
-        open_member_suggestions
-      end
-    end
+    include_examples "open suggestions when typing @"
   end
 
-  context 'adding a new note on a Commit ', js: true do
-    let(:commit)  { project.commit }
+  context 'adding a new note on a Commit' do
+    let(:noteable) { project.commit }
+    let(:note) { create(:note_on_commit, project: project, commit_id: project.commit.id) }
 
     before do
-      allow(commit).to receive(:author).and_return(author)
-      create(:note_on_commit, author: participant, project: project, commit_id: project.repository.commit.id, note: 'No More Parties in LA')
-      visit_commit(project, commit)
-    end
-
-    context 'when typing @' do
-      include_examples "open suggestions"
-      before do
-        open_member_suggestions
-      end
-    end
-  end
+      allow_any_instance_of(Commit).to receive(:author).and_return(author)
 
-  def open_member_suggestions
-    page.within('.new-note') do
-      find('#note_note').send_keys('@')
+      visit namespace_project_commit_path(project.namespace, project, noteable)
     end
-    wait_for_ajax
-  end
-
-  def visit_issue(project, issue)
-    visit namespace_project_issue_path(project.namespace, project, issue)
-  end
-
-  def visit_merge_request(project, merge)
-    visit namespace_project_merge_request_path(project.namespace, project, merge)
-  end
 
-  def visit_commit(project, commit)
-    visit namespace_project_commit_path(project.namespace, project, commit)
+    include_examples "open suggestions when typing @"
   end
 end

spec/spec_helper.rb

@@ -35,7 +35,8 @@ RSpec.configure do |config|
   config.include Warden::Test::Helpers, type: :request
   config.include LoginHelpers, type: :feature
   config.include SearchHelpers, type: :feature
-  config.include WaitForAjax, type: :feature
+  config.include WaitForRequests, :js
+  config.include WaitForAjax, :js
   config.include StubConfiguration
   config.include EmailHelpers, type: :mailer
   config.include TestEnv

spec/support/wait_for_requests.rb

+module WaitForRequests
+  extend self
+
+  # This is inspired by http://www.salsify.com/blog/engineering/tearing-capybara-ajax-tests
+  def wait_for_requests_complete
+    Gitlab::Testing::RequestBlockerMiddleware.block_requests!
+    wait_for('pending AJAX requests complete') do
+      Gitlab::Testing::RequestBlockerMiddleware.num_active_requests.zero?
+    end
+  ensure
+    Gitlab::Testing::RequestBlockerMiddleware.allow_requests!
+  end
+
+  # Waits until the passed block returns true
+  def wait_for(condition_name, max_wait_time: Capybara.default_max_wait_time, polling_interval: 0.01)
+    wait_until = Time.now + max_wait_time.seconds
+    loop do
+      break if yield
+      if Time.now > wait_until
+        raise "Condition not met: #{condition_name}"
+      else
+        sleep(polling_interval)
+      end
+    end
+  end
+end
+
+RSpec.configure do |config|
+  config.after(:each, :js) do
+    wait_for_requests_complete
+  end
+end