Add more tests to cover all cases

spec/services/application_settings/update_service_spec.rb

@@ -207,6 +207,18 @@ describe ApplicationSettings::UpdateService do
       described_class.new(application_settings, admin, { external_authorization_service_enabled: false }).execute
     end
 
+    it 'does validate labels if external authorization gets enabled ' do
+      expect_any_instance_of(described_class).to receive(:validate_classification_label)
+
+      described_class.new(application_settings, admin, { external_authorization_service_enabled: true }).execute
+    end
+
+    it 'does validate labels if external authorization is left unchanged' do
+      expect_any_instance_of(described_class).to receive(:validate_classification_label)
+
+      described_class.new(application_settings, admin, { external_authorization_service_default_label: 'new-label' }).execute
+    end
+
     it 'does not save the settings with an error if the service denies access' do
       expect(::Gitlab::ExternalAuthorization)
         .to receive(:access_allowed?).with(admin, 'new-label') { false }