feat: add e2e email delivery tests

Depends on a new scenario defined in gitlab-qa that launches a docker
image for mailhog and makes sure that email delivery via smtp is
performed correctly

changelogs/unreleased/qa-add-email-delivery-tests.yml

+---
+title: Add e2e qa test for email delivery
+merge_request: 20675
+author: Diego Louzán
+type: other

qa/qa.rb

@@ -15,6 +15,7 @@ module QA
   #
   module Flow
     autoload :Login, 'qa/flow/login'
+    autoload :Project, 'qa/flow/project'
   end
 
   ##
@@ -33,6 +34,7 @@ module QA
     autoload :Fixtures, 'qa/runtime/fixtures'
     autoload :Logger, 'qa/runtime/logger'
     autoload :GPG, 'qa/runtime/gpg'
+    autoload :MailHog, 'qa/runtime/mail_hog'
 
     module API
       autoload :Client, 'qa/runtime/api/client'
@@ -130,6 +132,7 @@ module QA
         autoload :Kubernetes, 'qa/scenario/test/integration/kubernetes'
         autoload :Mattermost, 'qa/scenario/test/integration/mattermost'
         autoload :ObjectStorage, 'qa/scenario/test/integration/object_storage'
+        autoload :SMTP, 'qa/scenario/test/integration/smtp'
       end
 
       module Sanity
@@ -422,6 +425,7 @@ module QA
       autoload :Maven, 'qa/service/docker_run/maven'
       autoload :NodeJs, 'qa/service/docker_run/node_js'
       autoload :GitlabRunner, 'qa/service/docker_run/gitlab_runner'
+      autoload :MailHog, 'qa/service/docker_run/mail_hog'
     end
   end
 

qa/qa/flow/project.rb

+# frozen_string_literal: true
+
+module QA
+  module Flow
+    module Project
+      module_function
+
+      def add_member(project:, username:)
+        project.visit!
+
+        Page::Project::Menu.perform(&:go_to_members_settings)
+
+        Page::Project::Settings::Members.perform do |member_settings|
+          member_settings.add_member(username)
+        end
+      end
+    end
+  end
+end

qa/qa/runtime/env.rb

@@ -281,6 +281,10 @@ module QA
         ENV.fetch('GITLAB_QA_LOOP_RUNNER_MINUTES', 1).to_i
       end
 
+      def mailhog_hostname
+        ENV['MAILHOG_HOSTNAME']
+      end
+
       private
 
       def remote_grid_credentials

qa/qa/runtime/mail_hog.rb

+# frozen_string_literal: true
+module QA
+  module Runtime
+    module MailHog
+      def self.base_url
+        host = QA::Runtime::Env.mailhog_hostname || 'localhost'
+        "http://#{host}:8025"
+      end
+
+      def self.api_messages_url
+        "#{base_url}/api/v2/messages"
+      end
+    end
+  end
+end

qa/qa/scenario/test/integration/smtp.rb

+# frozen_string_literal: true
+
+module QA
+  module Scenario
+    module Test
+      module Integration
+        class SMTP < Test::Instance::All
+          tags :smtp
+        end
+      end
+    end
+  end
+end

qa/qa/specs/features/browser_ui/1_manage/mail/trigger_mail_notification_spec.rb

+# frozen_string_literal: true
+
+module QA
+  context 'Manage', :orchestrated, :smtp do
+    describe 'mail notification' do
+      let(:user) do
+        Resource::User.fabricate_or_use(Runtime::Env.gitlab_qa_username_1, Runtime::Env.gitlab_qa_password_1)
+      end
+
+      let(:project) do
+        Resource::Project.fabricate_via_api! do |resource|
+          resource.name = 'email-notification-test'
+        end
+      end
+
+      before do
+        Flow::Login.sign_in
+      end
+
+      it 'user receives email for project invitation' do
+        Flow::Project.add_member(project: project, username: user.username)
+
+        expect(page).to have_content(/@#{user.username}(\n| )?Given access/)
+
+        # Wait for Action Mailer to deliver messages
+        mailhog_json = Support::Retrier.retry_until(sleep_interval: 1) do
+          Runtime::Logger.debug(%Q[retrieving "#{QA::Runtime::MailHog.api_messages_url}"]) if Runtime::Env.debug?
+
+          mailhog_response = get QA::Runtime::MailHog.api_messages_url
+
+          mailhog_data = JSON.parse(mailhog_response.body)
+
+          # Expect at least two invitation messages: group and project
+          mailhog_data if mailhog_data.dig('total') >= 2
+        end
+
+        # Check json result from mailhog
+        mailhog_items = mailhog_json.dig('items')
+        expect(mailhog_items).to include(an_object_satisfying { |o| /project was granted/ === o.dig('Content', 'Headers', 'Subject', 0) })
+      end
+    end
+  end
+end