Fix Delete activity handling when the status has been reblogged (#4729)

spec/lib/activitypub/activity/delete_spec.rb

@@ -25,4 +25,28 @@ RSpec.describe ActivityPub::Activity::Delete do
       expect(Status.find_by(id: status.id)).to be_nil
     end
   end
+
+  context 'when the status has been reblogged' do
+    describe '#perform' do
+      subject { described_class.new(json, sender) }
+      let(:reblogger) { Fabricate(:account) }
+      let(:follower)   { Fabricate(:account, username: 'follower', protocol: :activitypub, domain: 'example.com', inbox_url: 'http://example.com/inbox') }
+
+      before do
+        stub_request(:post, 'http://example.com/inbox').to_return(status: 200)
+        follower.follow!(reblogger)
+        Fabricate(:status, account: reblogger, reblog: status)
+        subject.perform
+      end
+
+      it 'deletes sender\'s status' do
+        expect(Status.find_by(id: status.id)).to be_nil
+      end
+
+      it 'sends delete activity to followers of rebloggers' do
+        # one for Delete original post, and one for Undo reblog (normal delivery)
+        expect(a_request(:post, 'http://example.com/inbox')).to have_been_made.twice
+      end
+    end
+  end
 end