Add basic coverage for some worker jobs (#23943)

spec/workers/cache_buster_worker_spec.rb

@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+describe CacheBusterWorker do
+  let(:worker) { described_class.new }
+
+  describe 'perform' do
+    let(:path) { 'https://example.com' }
+    let(:service) { instance_double(CacheBuster, bust: true) }
+
+    it 'calls the cache buster' do
+      allow(CacheBuster).to receive(:new).and_return(service)
+      worker.perform(path)
+
+      expect(service).to have_received(:bust).with(path)
+    end
+  end
+end