text: import unittest
  
  from django.db import NotSupportedError, connection
  from django.db.models import CharField
  from django.db.models.functions import SHA224
  from django.test import TestCase
  from django.test.utils import register_lookup
  
  from ..models import Author
  
  
  class SHA224Tests(TestCase):
      @classmethod
      def setUpTestData(cls):
          Author.objects.bulk_create([
              Author(alias='John Smith'),
              Author(alias='Jordan Élena'),
              Author(alias='皇帝'),
              Author(alias=''),
              Author(alias=None),
          ])
  
      def test_basic(self):
          authors = Author.objects.annotate(
              sha224_alias=SHA224('alias'),
          ).values_list('sha224_alias', flat=True).order_by('pk')
          self.assertSequenceEqual(
              authors,
              [
                  'a61303c220731168452cb6acf3759438b1523e768f464e3704e12f70',
                  '2297904883e78183cb118fc3dc21a610d60daada7b6ebdbc85139f4d',
                  'eba942746e5855121d9d8f79e27dfdebed81adc85b6bf41591203080',
                  'd14a028c2a3a2bc9476102bb288234c415a2b01f828ea62ac5b3e42f',
                  'd14a028c2a3a2bc9476102bb288234c415a2b01f828ea62ac5b3e42f'
                  if connection.features.interprets_empty_strings_as_nulls else None,
              ],
          )
  
      def test_transform(self):
          with register_lookup(CharField, SHA224):
              authors = Author.objects.filter(
                  alias__sha224='a61303c220731168452cb6acf3759438b1523e768f464e3704e12f70',
              ).values_list('alias', flat=True)
              self.assertSequenceEqual(authors, ['John Smith'])
  
      @unittest.skipUnless(connection.vendor == 'oracle', "Oracle doesn't support SHA224.")
      def test_unsupported(self):
          msg = 'SHA224 is not supported on Oracle.'
          with self.assertRaisesMessage(NotSupportedError, msg):
              Author.objects.annotate(sha224_alias=SHA224('alias')).first()
  