Fix: LD Signaturesで署名された投稿の検索許可（検索範囲）が改竄できる問題

spec/lib/activitypub/activity/create_spec.rb

@@ -564,7 +564,7 @@ RSpec.describe ActivityPub::Activity::Create do
         end
 
         context 'with direct' do
-          let(:searchable_by) { '' }
+          let(:searchable_by) { 'https://example.com/actor' }
 
           it 'create status' do
             status = sender.statuses.first
@@ -574,6 +574,17 @@ RSpec.describe ActivityPub::Activity::Create do
           end
         end
 
+        context 'with empty array' do
+          let(:searchable_by) { '' }
+
+          it 'create status' do
+            status = sender.statuses.first
+
+            expect(status).to_not be_nil
+            expect(status.searchability).to be_nil
+          end
+        end
+
         context 'with direct when not specify' do
           let(:searchable_by) { nil }