Add basic coverage for `AppealService` class (#29322)

spec/services/appeal_service_spec.rb

@@ -0,0 +1,40 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe AppealService do
+  describe '#call' do
+    let!(:admin) { Fabricate(:user, role: UserRole.find_by(name: 'Admin')) }
+
+    context 'with an existing strike' do
+      let(:strike) { Fabricate(:account_warning) }
+      let(:text) { 'Appeal text' }
+
+      it 'creates an appeal and notifies staff' do
+        emails = capture_emails { subject.call(strike, text) }
+
+        expect(Appeal.last)
+          .to have_attributes(
+            strike: strike,
+            text: text,
+            account: strike.target_account
+          )
+
+        expect(emails.size)
+          .to eq(1)
+
+        expect(emails.first)
+          .to have_attributes(
+            to: contain_exactly(admin.email),
+            subject: eq(
+              I18n.t(
+                'admin_mailer.new_appeal.subject',
+                username: strike.target_account.acct,
+                instance: Rails.configuration.x.local_domain
+              )
+            )
+          )
+      end
+    end
+  end
+end