          data = {'username': 'new-username', 'email': 'new-email@example.com'}
          rs = RelatedModelSerializer(data=data)
          self.assertTrue(rs.is_valid())
  
  
  # Tests for `UniqueTogetherValidator`
  # -----------------------------------
  
  class UniquenessTogetherModel(models.Model):
 
</s> remove         if None not in checked_values and queryset.exists():
 </s> add         if None not in checked_values and qs_exists(queryset): </s> remove         return queryset.filter(**filter_kwargs)
 </s> add         return qs_filter(queryset, **filter_kwargs) </s> remove         return queryset.filter(**filter_kwargs)
 </s> add         return qs_filter(queryset, **filter_kwargs) </s> remove         return queryset.filter(**filter_kwargs)
 </s> add         return qs_filter(queryset, **filter_kwargs)
    def test_value_error_treated_as_not_unique(self):
        serializer = UniquenessIntegerSerializer(data={'integer': 'abc'})
        assert serializer.is_valid()

          data = {'username': 'new-username', 'email': 'new-email@example.com'}
          rs = RelatedModelSerializer(data=data)
          self.assertTrue(rs.is_valid())
  
    def test_value_error_treated_as_not_unique(self):
        serializer = UniquenessIntegerSerializer(data={'integer': 'abc'})
        assert serializer.is_valid()

  
  # Tests for `UniqueTogetherValidator`
  # -----------------------------------
  
  class UniquenessTogetherModel(models.Model):
keep keep keep add keep keep keep keep keep
 Robust uniqueness checks. (#4217)

* Robust uniqueness checks
* Add master to test matrix (allow_failures) 
tests/test_validators.py