Move serializer import to top-level causes test error

rest_framework/tests/test_serializer_nested.py

@@ -6,6 +6,7 @@ Doesn't cover model serializers.
 from __future__ import unicode_literals
 from django.test import TestCase
 from rest_framework import serializers
+from rest_framework.tests.accounts.serializers import AccountSerializer
 from . import models
 
 
@@ -349,5 +350,4 @@ class NestedModelSerializerUpdateTests(TestCase):
 
 class ImportingModelSerializerWithStrForeignKeys(TestCase):
     def test_import_model_serializer(self):
-        from rest_framework.tests.accounts.serializers import AccountSerializer
         self.assertIsInstance(AccountSerializer(), serializers.ModelSerializer)