          data = {'url': 'http://testserver/nullableforeignkeysource/1/', 'name': 'source-1', 'target': ''}
          expected_data = {'url': 'http://testserver/nullableforeignkeysource/1/', 'name': 'source-1', 'target': None}
          instance = NullableForeignKeySource.objects.get(pk=1)
          serializer = NullableForeignKeySourceSerializer(instance, data=data, context={'request': request})
          self.assertTrue(serializer.is_valid())
          serializer.save()
          self.assertEqual(serializer.data, expected_data)
  
          # Ensure source 1 is updated, and everything else is as expected
          queryset = NullableForeignKeySource.objects.all()
 
</s> remove         self.assertTrue(serializer.is_valid())
 </s> add         assert serializer.is_valid() </s> remove         self.assertEqual(serializer.data, expected_data)
 </s> add         assert serializer.data == expected_data </s> remove         self.assertTrue(serializer.is_valid())
 </s> add         assert serializer.is_valid() </s> remove         self.assertEqual(serializer.data, data)
 </s> add         assert serializer.data == data </s> remove         self.assertEqual(serializer.data, expected_data)
        self.assertEqual(obj.name, 'source-4')
 </s> add         assert serializer.data == expected_data
        assert obj.name == 'source-4'
        assert serializer.is_valid()
          data = {'url': 'http://testserver/nullableforeignkeysource/1/', 'name': 'source-1', 'target': ''}
          expected_data = {'url': 'http://testserver/nullableforeignkeysource/1/', 'name': 'source-1', 'target': None}
          instance = NullableForeignKeySource.objects.get(pk=1)
          serializer = NullableForeignKeySourceSerializer(instance, data=data, context={'request': request})
        assert serializer.is_valid()
          serializer.save()
          self.assertEqual(serializer.data, expected_data)
  
          # Ensure source 1 is updated, and everything else is as expected
          queryset = NullableForeignKeySource.objects.all()
keep keep keep keep replace keep keep keep keep keep
 converted test asserts of hyperlin relations to pytest 
tests/test_relations_hyperlink.py