  from __future__ import unicode_literals
  
  from django.db.models.query_utils import DeferredAttribute, InvalidQuery
  from django.test import TestCase
  
  from .models import (
      BigChild, Child, ChildProxy, Primary, RefreshPrimaryProxy, Secondary,
  )
 
</s> remove from django.test.utils import isolate_apps
 </s> add  </s> remove from django.db.models.query_utils import (
    DeferredAttribute, deferred_class_factory,
)
 </s> add  </s> remove from django.apps import apps
 </s> add  </s> remove from django.db import models
 </s> add  </s> remove from django.db.models.query_utils import (
    DeferredAttribute, deferred_class_factory,
)
 </s> add 
from django.db.models.query_utils import InvalidQuery
  from __future__ import unicode_literals
  
from django.db.models.query_utils import InvalidQuery
  from django.test import TestCase
  
  from .models import (
      BigChild, Child, ChildProxy, Primary, RefreshPrimaryProxy, Secondary,
  )
keep keep replace keep keep keep keep keep
 Fixed #26207 -- Replaced dynamic classes with non-data descriptors for deferred instance loading. 
tests/defer/tests.py