More WEI tests, > 97 % coverage

apps/wei/forms/surveys/base.py

@@ -25,9 +25,7 @@ class WEISurveyInformation:
         If the algorithm ran, return the prefered bus according to the survey.
         In the other case, return None.
         """
-        if not self.valid:
-            return None
-        return Bus.objects.get(pk=self.selected_bus_pk)
+        return Bus.objects.get(pk=self.selected_bus_pk) if self.valid else None
 
     def save(self, registration) -> None:
         """