make possible to unarchive completed submission

spec/system/submission_spec.rb

@@ -0,0 +1,25 @@
+# frozen_string_literal: true
+
+RSpec.describe 'Submission' do
+  let(:account) { create(:account) }
+  let(:user) { create(:user, account:) }
+  let(:template) { create(:template, account:, author: user) }
+  let(:submission) do
+    create(:submission, :with_submitters, template:, created_by_user: user, archived_at: Time.current)
+  end
+
+  before do
+    sign_in(user)
+    submission.submitters.each { |s| s.update!(completed_at: 1.day.ago) }
+  end
+
+  it 'unarchives a completed submission from the download dropdown' do
+    visit submission_path(submission)
+
+    find('label[aria-label="Download"]').click
+    click_button 'Unarchive'
+
+    expect(page).to have_content('Submission has been unarchived.')
+    expect(submission.reload.archived_at).to be_nil
+  end
+end