Add basic coverage for `ApproveAppealService` class (#29333)

spec/services/approve_appeal_service_spec.rb

@@ -0,0 +1,30 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe ApproveAppealService do
+  describe '#call' do
+    context 'with an existing appeal' do
+      let(:appeal) { Fabricate(:appeal) }
+      let(:account) { Fabricate(:account) }
+
+      it 'processes the appeal approval' do
+        expect { subject.call(appeal, account) }
+          .to mark_overruled
+          .and record_approver
+      end
+
+      def mark_overruled
+        change(appeal.strike, :overruled_at)
+          .from(nil)
+          .to(be > 1.minute.ago)
+      end
+
+      def record_approver
+        change(appeal, :approved_by_account)
+          .from(nil)
+          .to(account)
+      end
+    end
+  end
+end