DRY up the added update service specs, add two email helpers

spec/services/issues/update_service_spec.rb

@@ -320,37 +320,10 @@ describe Issues::UpdateService, services: true do
       end
     end
 
-    context 'updated user mentions' do
-      let(:user4) { create(:user) }
-      before do
-        project.team << [user4, :developer]
-      end
-
-      context "in title" do
-        before do
-          perform_enqueued_jobs { update_issue(title: user4.to_reference) }
-        end
-
-        it 'emails only the newly-mentioned user' do
-          should_not_email(user)
-          should_not_email(user2)
-          should_not_email(user3)
-          should_email(user4)
-        end
-      end
-
-      context 'in description' do
-        before do
-          perform_enqueued_jobs { update_issue(description: user4.to_reference) }
-        end
-
-        it 'emails only the newly-mentioned user' do
-          should_not_email(user)
-          should_not_email(user2)
-          should_not_email(user3)
-          should_email(user4)
-        end
-      end
+    context 'updating mentions' do
+      let(:mentionable) { issue }
+      include_examples 'updating mentions', Issues::UpdateService
     end
+
   end
 end

spec/services/merge_requests/update_service_spec.rb

@@ -226,37 +226,9 @@ describe MergeRequests::UpdateService, services: true do
       end
     end
 
-    context 'updated user mentions' do
-      let(:user4) { create(:user) }
-      before do
-        project.team << [user4, :developer]
-      end
-
-      context 'in title' do
-        before do
-          perform_enqueued_jobs { update_merge_request(title: user4.to_reference) }
-        end
-
-        it 'emails only the newly-mentioned user' do
-          should_not_email(user)
-          should_not_email(user2)
-          should_not_email(user3)
-          should_email(user4)
-        end
-      end
-
-      context 'in description' do
-        before do
-          perform_enqueued_jobs { update_merge_request(description: user4.to_reference) }
-        end
-
-        it 'emails only the newly-mentioned user' do
-          should_not_email(user)
-          should_not_email(user2)
-          should_not_email(user3)
-          should_email(user4)
-        end
-      end
+    context 'updating mentions' do
+      let(:mentionable) { merge_request }
+      include_examples 'updating mentions', MergeRequests::UpdateService
     end
 
     context 'when MergeRequest has tasks' do

spec/support/email_helpers.rb

@@ -3,6 +3,16 @@ module EmailHelpers
     ActionMailer::Base.deliveries.map(&:to).flatten.count(user.email) == 1
   end
 
+  def reset_delivered_emails!
+    ActionMailer::Base.deliveries.clear
+  end
+
+  def should_only_email(*users)
+    users.each {|user| should_email(user) }
+    recipients = ActionMailer::Base.deliveries.flat_map(&:to)
+    expect(recipients.count).to eq(users.count)
+  end
+
   def should_email(user)
     expect(sent_to_user?(user)).to be_truthy
   end

spec/support/updating_mentions_shared_examples.rb

@@ -0,0 +1,32 @@
+RSpec.shared_examples 'updating mentions' do |service_class|
+  let(:mentioned_user) { create(:user) }
+  let(:service_class) { service_class }
+
+  before { project.team << [mentioned_user, :developer] }
+
+  def update_mentionable(opts)
+    reset_delivered_emails!
+
+    perform_enqueued_jobs do
+      service_class.new(project, user, opts).execute(mentionable)
+    end
+
+    mentionable.reload
+  end
+
+  context 'in title' do
+    before { update_mentionable(title: mentioned_user.to_reference) }
+
+    it 'emails only the newly-mentioned user' do
+      should_only_email(mentioned_user)
+    end
+  end
+
+  context 'in description' do
+    before { update_mentionable(description: mentioned_user.to_reference) }
+
+    it 'emails only the newly-mentioned user' do
+      should_only_email(mentioned_user)
+    end
+  end
+end