test: that validate_nulls gets header if check_answer_label is missing

spec/services/bulk_upload/lettings/year2023/row_parser_spec.rb

@@ -236,6 +236,16 @@ RSpec.describe BulkUpload::Lettings::Year2023::RowParser do
           expect(questions.map(&:id)).to eql([])
         end
       end
+
+      describe "#validate_nulls" do
+        let(:attributes) { { bulk_upload:, field_19: "", field_21: "" } }
+
+        it "fetches the question's check_answer_label if it exists, otherwise it get's the question's header" do
+          parser.valid?
+          expect(parser.errors[:field_19]).to eql(["You must answer q12 - address"])
+          expect(parser.errors[:field_21]).to eql(["You must answer town or city"])
+        end
+      end
     end
 
     context "when setup section not complete" do