              {'name': u'source-1', 'target': None},
              {'name': u'source-2', 'target': 'target-1'},
              {'name': u'source-3', 'target': None},
          ]
          serializer = NullOKSluggedNullableForeignKeySourceSerializer(queryset)
          self.assertEquals(serializer.data, expected)
  
          serializer = NotRequiredSluggedNullableForeignKeySourceSerializer(queryset)
          self.assertEquals(serializer.data, expected)
  
 
</s> remove         serializer = NullOKSluggedNullableForeignKeySourceSerializer(queryset)
 </s> add  </s> remove 
        serializer = DefaultSluggedNullableForeignKeySourceSerializer(queryset)
        self.assertEquals(serializer.data, default_expected)

        serializer = NotRequiredSluggedNullableForeignKeySourceSerializer(queryset)
        self.assertEquals(serializer.data, expected)

        serializer = NullOKSluggedNullableForeignKeySourceSerializer(queryset)
 </s> add  </s> remove         serializer = NotRequiredSluggedNullableForeignKeySourceSerializer(queryset)
        self.assertEquals(serializer.data, expected)

 </s> add  </s> remove         #BUG: All serializers fail here
        serializer = DefaultSluggedNullableForeignKeySourceSerializer(queryset)
        self.assertEquals(serializer.data, default_expected)
        serializer = NullOKSluggedNullableForeignKeySourceSerializer(queryset)
        self.assertEquals(serializer.data, expected)
        serializer = NotRequiredSluggedNullableForeignKeySourceSerializer(queryset)
 </s> add  </s> remove         serializer = NotRequiredSluggedNullableForeignKeySourceSerializer(queryset)
        self.assertEquals(serializer.data, expected)

        expected = [
            {'name': u'source-1', 'target': 'N/A'},
            {'name': u'source-2', 'target': 'target-1'},
            {'name': u'source-3', 'target': 'N/A'},
        ]
        serializer = NullOKSluggedNullableForeignKeySourceSerializer(queryset)
        self.assertEquals(serializer.data, expected)

    def test_slug_foreign_key_update_with_valid_emptystring(self):
 </s> add     def test_foreign_key_update_with_valid_emptystring(self):
              {'name': u'source-1', 'target': None},
              {'name': u'source-2', 'target': 'target-1'},
              {'name': u'source-3', 'target': None},
          ]

          self.assertEquals(serializer.data, expected)
  
          serializer = NotRequiredSluggedNullableForeignKeySourceSerializer(queryset)
          self.assertEquals(serializer.data, expected)
  
keep keep keep keep replace keep keep keep keep keep
 Drop bits of relations_slug tests which don't mirror existing tests. 
rest_framework/tests/relations_slug.py