feat: add test

spec/services/imports/lettings_logs_import_service_spec.rb

@@ -566,6 +566,27 @@ RSpec.describe Imports::LettingsLogsImportService do
         end
       end
 
+      context "and the number of times the property was relet is a non nil string that is nil as a BigDecimal" do
+        before do
+          lettings_log_xml.at_xpath("//xmlns:Q20").content = "a"
+        end
+
+        it "doesn't throw an error" do
+          expect { lettings_log_service.send(:create_log, lettings_log_xml) }
+            .not_to raise_error
+        end
+
+        it "clears out the number offered answer" do
+          allow(logger).to receive(:warn)
+
+          lettings_log_service.send(:create_log, lettings_log_xml)
+          lettings_log = LettingsLog.find_by(old_id: lettings_log_id)
+
+          expect(lettings_log).not_to be_nil
+          expect(lettings_log.offered).to be_nil
+        end
+      end
+
       context "and the gender identity is refused" do
         before do
           lettings_log_xml.at_xpath("//xmlns:P1Sex").content = "Person prefers not to say"