          self.assertEquals(serializer.data, expected)
          serializer = DefaultSluggedNullableForeignKeySourceSerializer(data=data)
          self.assertEquals(serializer.data, default_expected)
  
      def test_slug_foreign_key_create_with_valid_emptystring(self):
          """
          The emptystring should be interpreted as null in the context
          of relationships.
          """
          data = {'name': u'source-4', 'target': ''}
 
</s> remove         serializer = DefaultSluggedNullableForeignKeySourceSerializer(data=data)
        self.assertEquals(serializer.data, default_expected)
 </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): </s> remove         data = {'name': u'source-4', 'target': ''}
        expected_data = {'name': u'source-4', 'target': None}

        serializer = SluggedNullableForeignKeySourceSerializer(data=data)
        self.assertFalse(serializer.is_valid())
        self.assertEquals(serializer.errors, {'target': [u'Value may not be null']})

        serializer = NullOKSluggedNullableForeignKeySourceSerializer(data=data)
 </s> add         data = {'id': 4, 'name': u'source-4', 'target': ''}
        expected_data = {'id': 4, 'name': u'source-4', 'target': None}
        serializer = NullableSlugSourceSerializer(data=data) </s> remove         data = {'name': u'source-1', 'target': ''}
        default_data = {'name': u'source-1', 'target': 'N/A'}
        expected_data = {'name': u'source-1', 'target': None}
 </s> add         data = {'id': 1, 'name': u'source-1', 'target': ''}
        expected_data = {'id': 1, 'name': u'source-1', 'target': None} </s> remove         serializer = NullOKSluggedNullableForeignKeySourceSerializer(data=data)
        self.assertEquals(serializer.data, expected)
        serializer = NotRequiredSluggedNullableForeignKeySourceSerializer(data=data)
 </s> add 
    def test_foreign_key_create_with_valid_emptystring(self):
          self.assertEquals(serializer.data, expected)
          serializer = DefaultSluggedNullableForeignKeySourceSerializer(data=data)
          self.assertEquals(serializer.data, default_expected)
  
    def test_foreign_key_create_with_valid_emptystring(self):
          """
          The emptystring should be interpreted as null in the context
          of relationships.
          """
          data = {'name': u'source-4', 'target': ''}
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