db(procedure): add a maintenance task to backfill closed procedures with closing reason

spec/tasks/maintenance/backfill_closing_reason_in_closed_procedures_task_spec.rb

@@ -0,0 +1,30 @@
+# frozen_string_literal: true
+
+require "rails_helper"
+
+module Maintenance
+  RSpec.describe BackfillClosingReasonInClosedProceduresTask do
+    describe "#process" do
+      subject(:process) { described_class.process(procedure) }
+
+      context 'with a closed and replaced procedure' do
+        let(:published_procedure) { create(:procedure, :published) }
+        let(:procedure) { create(:procedure, :closed, replaced_by_procedure_id: published_procedure.id) }
+
+        it 'fills closing_reason with internal_procedure' do
+          subject
+          expect(procedure.closing_reason).to eq Procedure.closing_reasons.fetch(:internal_procedure)
+        end
+      end
+
+      context 'with a closed and not replaced procedure' do
+        let(:procedure) { create(:procedure, :closed) }
+
+        it 'fills closing_reason with other' do
+          subject
+          expect(procedure.closing_reason).to eq Procedure.closing_reasons.fetch(:other)
+        end
+      end
+    end
+  end
+end