Add preference for report notification e-mails, skip for duplicates (#8559)

If an unresolved report for the same target account already exists,
no new notification is generated

spec/services/report_service_spec.rb

@@ -3,7 +3,7 @@ require 'rails_helper'
 RSpec.describe ReportService, type: :service do
   subject { described_class.new }
 
-  let(:source_account) { Fabricate(:account) }
+  let(:source_account) { Fabricate(:user).account }
 
   context 'for a remote account' do
     let(:remote_account) { Fabricate(:account, domain: 'example.com', protocol: :activitypub, inbox_url: 'http://example.com/inbox') }
@@ -22,4 +22,22 @@ RSpec.describe ReportService, type: :service do
       expect(a_request(:post, 'http://example.com/inbox')).to_not have_been_made
     end
   end
+
+  context 'when other reports already exist for the same target' do
+    let!(:target_account) { Fabricate(:account) }
+    let!(:other_report)   { Fabricate(:report, target_account: target_account) }
+
+    subject do
+      -> {  described_class.new.call(source_account, target_account) }
+    end
+
+    before do
+      ActionMailer::Base.deliveries.clear
+      source_account.user.settings.notification_emails['report'] = true
+    end
+
+    it 'does not send an e-mail' do
+      is_expected.to_not change(ActionMailer::Base.deliveries, :count).from(0)
+    end
+  end
 end