Fixed #29658 -- Registered model lookups in tests with a context manager.

tests/db_functions/math/test_ceil.py

@@ -4,6 +4,7 @@ from decimal import Decimal
 from django.db.models import DecimalField
 from django.db.models.functions import Ceil
 from django.test import TestCase
+from django.test.utils import register_lookup
 
 from ..models import DecimalModel, FloatModel, IntegerModel
 
@@ -41,11 +42,8 @@ class CeilTests(TestCase):
         self.assertEqual(obj.big_ceil, math.ceil(obj.big))
 
     def test_transform(self):
-        try:
-            DecimalField.register_lookup(Ceil)
+        with register_lookup(DecimalField, Ceil):
             DecimalModel.objects.create(n1=Decimal('3.12'), n2=Decimal('0'))
             DecimalModel.objects.create(n1=Decimal('1.25'), n2=Decimal('0'))
             objs = DecimalModel.objects.filter(n1__ceil__gt=3)
             self.assertQuerysetEqual(objs, [Decimal('3.12')], lambda a: a.n1)
-        finally:
-            DecimalField._unregister_lookup(Ceil)