          with connection.schema_editor() as editor:
              editor.alter_field(Tag, new_field2, new_field3, strict=True)
          # Ensure the field is still unique
          TagUniqueRename.objects.create(title="foo", slug2="foo")
          self.assertRaises(IntegrityError, TagUniqueRename.objects.create, title="bar", slug2="foo")
          Tag.objects.all().delete()
  
      def test_unique_together(self):
          """
          Tests removing and adding unique_together constraints on a model.
 
</s> remove         self.assertRaises(IntegrityError, Tag.objects.create, title="bar", slug="foo")
 </s> add         with self.assertRaises(IntegrityError):
            Tag.objects.create(title="bar", slug="foo") </s> remove         self.assertRaises(IntegrityError, UniqueTest.objects.create, year=2012, slug="foo")
 </s> add         with self.assertRaises(IntegrityError):
            UniqueTest.objects.create(year=2012, slug="foo") </s> remove         self.assertRaises(IntegrityError, Tag.objects.create, title="bar", slug="foo")
 </s> add         with self.assertRaises(IntegrityError):
            Tag.objects.create(title="bar", slug="foo") </s> remove         self.assertRaises(IntegrityError, UniqueTest.objects.create, year=2012, slug="foo")
 </s> add         with self.assertRaises(IntegrityError):
            UniqueTest.objects.create(year=2012, slug="foo") </s> remove         self.assertRaises(DatabaseError, self.column_classes, new_field.remote_field.through)
 </s> add         with self.assertRaises(DatabaseError):
            self.column_classes(new_field.remote_field.through)
        with self.assertRaises(IntegrityError):
            TagUniqueRename.objects.create(title="bar", slug2="foo")
          with connection.schema_editor() as editor:
              editor.alter_field(Tag, new_field2, new_field3, strict=True)
          # Ensure the field is still unique
          TagUniqueRename.objects.create(title="foo", slug2="foo")
        with self.assertRaises(IntegrityError):
            TagUniqueRename.objects.create(title="bar", slug2="foo")
          Tag.objects.all().delete()
  
      def test_unique_together(self):
          """
          Tests removing and adding unique_together constraints on a model.
keep keep keep keep replace keep keep keep keep keep
 Refs #26022 -- Used context manager version of assertRaises in tests. 
tests/schema/tests.py