Simplify tests using delayed_job

Among other advantages, now we can run these tests with
`rspec --tag delayed_jobs`.

spec/controllers/remote_translation_controller_spec.rb

@@ -2,7 +2,7 @@ require "rails_helper"
 
 describe RemoteTranslationsController do
 
-  describe "POST create" do
+  describe "POST create", :delay_jobs do
     let(:debate)             { create(:debate) }
 
     before do
@@ -10,11 +10,6 @@ describe RemoteTranslationsController do
                                        remote_translatable_type: debate.class.to_s,
                                        locale: :es }].to_json
       request.env["HTTP_REFERER"] = "any_path"
-      Delayed::Worker.delay_jobs = true
-    end
-
-    after do
-      Delayed::Worker.delay_jobs = false
     end
 
     it "create correctly remote translation" do

spec/features/notifications_spec.rb

@@ -181,7 +181,7 @@ describe "Notifications" do
     end
   end
 
-  describe "#send_pending" do
+  describe "#send_pending", :delay_jobs do
     let!(:user1) { create(:user) }
     let!(:user2) { create(:user) }
     let!(:user3) { create(:user) }
@@ -192,11 +192,6 @@ describe "Notifications" do
       create(:notification, notifiable: proposal_notification, user: user2)
       create(:notification, notifiable: proposal_notification, user: user3)
       reset_mailer
-      Delayed::Worker.delay_jobs = true
-    end
-
-    after do
-      Delayed::Worker.delay_jobs = false
     end
 
     it "sends pending proposal notifications" do

spec/models/newsletter_spec.rb

@@ -64,7 +64,7 @@ describe Newsletter do
     end
   end
 
-  describe "#deliver" do
+  describe "#deliver", :delay_jobs do
     let!(:proposals) { Array.new(3) { create(:proposal) } }
 
     let!(:recipients) { proposals.map(&:author).map(&:email) }
@@ -73,11 +73,6 @@ describe Newsletter do
     before do
       create(:debate)
       reset_mailer
-      Delayed::Worker.delay_jobs = true
-    end
-
-    after do
-      Delayed::Worker.delay_jobs = false
     end
 
     it "sends an email with the newsletter to every recipient" do

spec/models/remote_translation_spec.rb

@@ -28,16 +28,7 @@ describe RemoteTranslation do
     expect(remote_translation).not_to be_valid
   end
 
-  describe "#enqueue_remote_translation" do
-
-    before do
-      Delayed::Worker.delay_jobs = true
-    end
-
-    after do
-      Delayed::Worker.delay_jobs = false
-    end
-
+  describe "#enqueue_remote_translation", :delay_jobs do
     it "after create enqueue Delayed Job" do
       expect { remote_translation.save }.to change { Delayed::Job.count }.by(1)
     end

spec/shared/features/remotely_translatable.rb

@@ -48,10 +48,7 @@ shared_examples "remotely_translatable" do |factory_name, path_name, path_argume
       expect(page).not_to have_button("Translate page")
     end
 
-    describe "with delayed job active" do
-      before { Delayed::Worker.delay_jobs = true }
-      after  { Delayed::Worker.delay_jobs = false }
-
+    describe "with delayed job active", :delay_jobs do
       scenario "should not be present when an equal RemoteTranslation is enqueued", :js do
         create(:remote_translation, remote_translatable: resource, locale: :de)
         visit path
@@ -154,16 +151,7 @@ shared_examples "remotely_translatable" do |factory_name, path_name, path_argume
 
   context "After click remote translations button" do
 
-    describe "with delayed jobs" do
-
-      before do
-        Delayed::Worker.delay_jobs = true
-      end
-
-      after do
-        Delayed::Worker.delay_jobs = false
-      end
-
+    describe "with delayed jobs", :delay_jobs do
       scenario "the remote translation button should not be present", :js do
         visit path
         select("Deutsch", from: "locale-switcher")

spec/spec_helper.rb

@@ -93,6 +93,14 @@ RSpec.configure do |config|
     Bullet.end_request
   end
 
+  config.before(:each, :delay_jobs) do
+    Delayed::Worker.delay_jobs = true
+  end
+
+  config.after(:each, :delay_jobs) do
+    Delayed::Worker.delay_jobs = false
+  end
+
   config.before(:each, :with_frozen_time) do
     travel_to Time.now # TODO: use `freeze_time` after migrating to Rails 5.
   end