Add service for creating promotion batch

app/services/create_promotion_batch.rb

@@ -0,0 +1,7 @@
+class CreatePromotionBatch
+  def self.call(promotion, size)
+    size.times do
+      DuplicatePromotionJob.perform_async(promotion.id)
+    end
+  end
+end

spec/services/create_promotion_batch_spec.rb

@@ -0,0 +1,19 @@
+require 'spec_helper'
+
+describe CreatePromotionBatch do
+  describe "#call" do
+    subject(:batch) { described_class.call(promotion, size) }
+
+    let(:promotion) { create(:promotion) }
+    let(:size) { 50 }
+
+    it "enqueues DuplicatePromotionJob jobs", sidekiq: :inline do
+      expect(DuplicatePromotionJob)
+        .to receive(:perform_async)
+        .at_least(50).times
+        .with(promotion.id)
+
+      batch
+    end
+  end
+end