Add private method for event export filename (#38454)

spec/models/account_relationship_severance_event_spec.rb

@@ -0,0 +1,20 @@
+# frozen_string_literal: true
+
+RSpec.describe AccountRelationshipSeveranceEvent do
+  describe 'Associations' do
+    it { is_expected.to belong_to(:account) }
+    it { is_expected.to belong_to(:relationship_severance_event) }
+    it { is_expected.to have_many(:severed_relationships).through(:relationship_severance_event) }
+  end
+
+  describe '#identifier' do
+    subject { account_relationship_severance_event.identifier }
+
+    let(:account_relationship_severance_event) { Fabricate.build :account_relationship_severance_event, relationship_severance_event:, created_at: DateTime.new(2026, 3, 15, 1, 2, 3) }
+    let(:relationship_severance_event) { Fabricate.build :relationship_severance_event, target_name: 'host.example' }
+
+    context 'with a hostname target and timestamp' do
+      it { is_expected.to eq('host.example-2026-03-15') }
+    end
+  end
+end