Add basic coverage for `RemoveDomainsFromFollowersService` class (#29327)

spec/services/remove_domains_from_followers_service_spec.rb

@@ -0,0 +1,28 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe RemoveDomainsFromFollowersService do
+  describe '#call' do
+    context 'with account followers' do
+      let(:account) { Fabricate(:account, domain: nil) }
+      let(:good_domain_account) { Fabricate(:account, domain: 'good.example', protocol: :activitypub) }
+      let(:bad_domain_account) { Fabricate(:account, domain: 'bad.example', protocol: :activitypub) }
+
+      before do
+        Fabricate :follow, target_account: account, account: good_domain_account
+        Fabricate :follow, target_account: account, account: bad_domain_account
+      end
+
+      it 'removes followers from supplied domains and sends a notification' do
+        subject.call(account, ['bad.example'])
+
+        expect(account.followers)
+          .to include(good_domain_account)
+          .and not_include(bad_domain_account)
+        expect(ActivityPub::DeliveryWorker)
+          .to have_enqueued_sidekiq_job(anything, account.id, bad_domain_account.inbox_url)
+      end
+    end
+  end
+end