[REFACTOR] Change is_positive condition in case serializers

apps/cases/serializers.py

@@ -93,7 +93,7 @@ class InvestigationCaseSerializer(serializers.ModelSerializer):
         outcome = self.validated_data.get('outcome', None)
         is_positive = None
         if outcome is not None:
-            is_positive = True if "+" in outcome else False
+            is_positive = False if "-" in outcome else True
 
         super(InvestigationCaseSerializer, self).save(author=account, is_positive=is_positive)