CLDC-2659 complete logs with no location (#1931)

* WIP fix

* feat: update status before validation to prevent issue in future

* feat: reprivatise update_status!

* feat: revert before_save -> before_validation

* feat: add test

* feat: lint

* refactor: lint

app/models/derived_variables/lettings_log_variables.rb

@@ -275,7 +275,7 @@ private
   def reset_scheme_location!
     self.location = nil
     if scheme && scheme.locations.active_in_2_weeks.size == 1
-      self.location = scheme.locations.first
+      self.location = scheme.locations.active_in_2_weeks.first
     end
   end
 

spec/models/lettings_log_spec.rb

@@ -2035,6 +2035,21 @@ RSpec.describe LettingsLog do
         allow(FormHandler.instance).to receive(:get_form).and_return(real_2021_2022_form)
       end
 
+      describe "when changing a log's scheme and hence calling reset_scheme_location!" do
+        let(:scheme) { FactoryBot.create(:scheme) }
+        let(:invalid_location_1) { FactoryBot.create(:location, scheme:, startdate: Time.zone.today + 3.weeks) }
+        let(:valid_location) { FactoryBot.create(:location, scheme:, startdate: Time.zone.yesterday) }
+        let(:invalid_location_2) { FactoryBot.create(:location, scheme:, startdate: Time.zone.today + 3.weeks) }
+
+        context "when there is one valid location and many invalid locations in the new scheme" do
+          let(:log) { create(:lettings_log, scheme: nil, location_id: nil, startdate: Time.zone.today) }
+
+          it "infers that the log is for the valid location" do
+            expect { log.update!(scheme:) }.to change(log, :location_id).from(nil).to(valid_location.id)
+          end
+        end
+      end
+
       context "and a scheme with a single log is selected" do
         let(:scheme) { create(:scheme) }
         let!(:location) { create(:location, scheme:) }