      target = serializers.SlugRelatedField(slug_field='name', default='N/A')
      class Meta:
          model = NullableForeignKeySource
  
  class NotRequiredSluggedNullableForeignKeySourceSerializer(serializers.ModelSerializer):
      target = serializers.SlugRelatedField(slug_field='name', required=False)
      class Meta:
          model = NullableForeignKeySource
  
  
  class SluggedNullableForeignKeyTests(TestCase):
  
      def setUp(self):
 
</s> remove class DefaultSluggedNullableForeignKeySourceSerializer(serializers.ModelSerializer):
    target = serializers.SlugRelatedField(slug_field='name', default='N/A')
 </s> add  </s> remove     class Meta:
        model = NullableForeignKeySource
 </s> add  </s> remove 
# Nullable ForeignKey
class SluggedNullableForeignKeySourceSerializer(serializers.ModelSerializer):
    target = serializers.SlugRelatedField(slug_field='name')
    class Meta:
        model = NullableForeignKeySource

class NullOKSluggedNullableForeignKeySourceSerializer(serializers.ModelSerializer):
 </s> add class NullableSlugSourceSerializer(serializers.ModelSerializer): </s> remove class SluggedNullableForeignKeyTests(TestCase):

 </s> add class SlugNullableForeignKeyTests(TestCase):
      target = serializers.SlugRelatedField(slug_field='name', default='N/A')
      class Meta:
          model = NullableForeignKeySource
  




  
  
  class SluggedNullableForeignKeyTests(TestCase):
  
      def setUp(self):
keep keep keep keep replace replace replace replace keep keep keep keep keep
 Drop bits of relations_slug tests which don't mirror existing tests. 
rest_framework/tests/relations_slug.py