diff -r 5ff1fc726848 -r c6bca38c1cbf parts/django/tests/modeltests/force_insert_update/tests.py
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/parts/django/tests/modeltests/force_insert_update/tests.py	Sat Jan 08 11:20:57 2011 +0530
@@ -0,0 +1,38 @@
+from django.db import transaction, IntegrityError, DatabaseError
+from django.test import TestCase
+
+from models import Counter, WithCustomPK
+
+
+class ForceTests(TestCase):
+    def test_force_update(self):
+        c = Counter.objects.create(name="one", value=1)
+        # The normal case
+
+        c.value = 2
+        c.save()
+        # Same thing, via an update
+        c.value = 3
+        c.save(force_update=True)
+
+        # Won't work because force_update and force_insert are mutually
+        # exclusive
+        c.value = 4
+        self.assertRaises(ValueError, c.save, force_insert=True, force_update=True)
+
+        # Try to update something that doesn't have a primary key in the first
+        # place.
+        c1 = Counter(name="two", value=2)
+        self.assertRaises(ValueError, c1.save, force_update=True)
+        c1.save(force_insert=True)
+
+        # Won't work because we can't insert a pk of the same value.
+        sid = transaction.savepoint()
+        c.value = 5
+        self.assertRaises(IntegrityError, c.save, force_insert=True)
+        transaction.savepoint_rollback(sid)
+
+        # Trying to update should still fail, even with manual primary keys, if
+        # the data isn't in the database already.
+        obj = WithCustomPK(name=1, value=1)
+        self.assertRaises(DatabaseError, obj.save, force_update=True)