API の処理に時間がかかりすぎる問題 (#442) (#449)

Reviewed-on: #449
Co-authored-by: miteruzo <miteruzo@naver.com>

backend/spec/services/counts_export_spec.rb

@@ -221,9 +221,15 @@ RSpec.describe CountsExportDownload::ResponseBody do
       body = described_class.new(source) { |state| states << state; true }
       response = ActionDispatch::Response.new
       response.body = body
-      deferred = response.stream.to_ary
+
+      _, _, rack_body = response.to_a
+
       expect(states).to eq([])
-      expect(deferred.to_a.join).to eq(payload)
+
+      chunks = []
+      rack_body.each { |chunk| chunks << chunk }
+
+      expect(chunks.join).to eq(payload)
       expect(states.count('started')).to eq(1)
     end
   end