Filter out Crossref-Crossref relationships from Crossref datacitation API import

app/models/crossref.rb

@@ -101,6 +101,11 @@ def push_data(result, _options = {})
     # Rails.logger.info "Extracting related identifiers for #{items.size} DOIs updated from #{options[:from_date]} until #{options[:until_date]}."
 
     Array.wrap(items).map do |item|
+      subj_ra = item.dig("subject", "registration-agency")
+      obj_ra = item.dig("object", "registration-agency")
+
+      next if subj_ra&.downcase == "crossref" && obj_ra&.downcase == "crossref"
+
       CrossrefImportJob.perform_later(item)
     end
   end

spec/models/crossref_spec.rb

@@ -112,19 +112,19 @@
   describe "#push_item" do
     it "sends a message to the events queue" do
       allow(Crossref).to(receive(:send_event_import_message).and_return(nil))
-      allow(Base).to(receive(:cached_crossref_response).and_return({ subj: "subj" }))
-      allow(Base).to(receive(:cached_datacite_response).and_return({ obj: "obj" }))
+      allow(described_class).to(receive(:cached_crossref_response).and_return({ subj: "subj" }))
+      allow(described_class).to(receive(:cached_datacite_response).and_return({ obj: "obj" }))
       allow(Rails.logger).to(receive(:info))
 
       item = {
         "timestamp" => "2002-07-25T03:18:25Z",
         "relation" => "example_relation_type",
         "subject" => {
-          "id" => "example_subj_id"
+          "id" => "example_subj_id",
         },
         "object" => {
-          "id" => "example_obj_id"
-        }
+          "id" => "example_obj_id",
+        },
       }
 
       Crossref.push_item(item)
@@ -133,4 +133,48 @@
       expect(Rails.logger).to(have_received(:info).with("[Event Data] example_subj_id example_relation_type example_obj_id sent to the events queue."))
     end
   end
+
+  describe "#push_data" do
+    let(:model) { described_class.new }
+
+    let(:item_crossref_to_datacite) do
+      {
+        "subject" => { "id" => "https://doi.org/10.1234/subj", "registration-agency" => "Crossref" },
+        "object" => { "id" => "https://doi.org/10.5678/obj", "registration-agency" => "DataCite" },
+      }
+    end
+
+    let(:item_crossref_to_crossref) do
+      {
+        "subject" => { "id" => "https://doi.org/10.1234/subj", "registration-agency" => "Crossref" },
+        "object" => { "id" => "https://doi.org/10.5678/obj", "registration-agency" => "Crossref" },
+      }
+    end
+
+    let(:result_crossref_to_datacite) do
+      instance_double(Faraday::Response,
+                      body: { "data" => { "message" => { "items" => [item_crossref_to_datacite] } } })
+    end
+
+    let(:result_crossref_to_crossref) do
+      instance_double(Faraday::Response,
+                      body: { "data" => { "message" => { "items" => [item_crossref_to_crossref] } } })
+    end
+
+    it "does not enqueue when both subject and object are Crossref" do
+      allow(CrossrefImportJob).to receive(:perform_later)
+
+      model.push_data(result_crossref_to_crossref)
+
+      expect(CrossrefImportJob).not_to have_received(:perform_later)
+    end
+
+    it "enqueues when object is DataCite" do
+      allow(CrossrefImportJob).to receive(:perform_later)
+
+      model.push_data(result_crossref_to_datacite)
+
+      expect(CrossrefImportJob).to have_received(:perform_later).once
+    end
+  end
 end