Fixed #11665 -- Made TestCase check deferrable constraints after each test.

tests/test_utils/test_testcase.py

@@ -0,0 +1,20 @@
+from django.db import IntegrityError, transaction
+from django.test import TestCase, skipUnlessDBFeature
+
+from .models import PossessedCar
+
+
+class TestTestCase(TestCase):
+
+    @skipUnlessDBFeature('can_defer_constraint_checks')
+    @skipUnlessDBFeature('supports_foreign_keys')
+    def test_fixture_teardown_checks_constraints(self):
+        rollback_atomics = self._rollback_atomics
+        self._rollback_atomics = lambda connection: None  # noop
+        try:
+            car = PossessedCar.objects.create(car_id=1, belongs_to_id=1)
+            with self.assertRaises(IntegrityError), transaction.atomic():
+                self._fixture_teardown()
+            car.delete()
+        finally:
+            self._rollback_atomics = rollback_atomics