[2.0.x] Fixed #29126 -- Doc'd the behavior of QuerySet.update_or_create() with manually specified pks.

Backport of e917ea6bec45d7f789ca96a13be15df9521963e1 from master

1 files changed, 13 insertions, 0 deletions

diff --git a/tests/get_or_create/tests.py b/tests/get_or_create/tests.py
index 60e1ef23f2..1aed318608 100644
--- a/tests/get_or_create/tests.py
+++ b/tests/get_or_create/tests.py
@@ -444,6 +444,19 @@ class UpdateOrCreateTests(TestCase):
         self.assertEqual(obj.last_name, 'NotHarrison')
 
 
+class UpdateOrCreateTestsWithManualPKs(TestCase):
+
+    def test_create_with_duplicate_primary_key(self):
+        """
+        If an existing primary key is specified with different values for other
+        fields, then IntegrityError is raised and data isn't updated.
+        """
+        ManualPrimaryKeyTest.objects.create(id=1, data='Original')
+        with self.assertRaises(IntegrityError):
+            ManualPrimaryKeyTest.objects.update_or_create(id=1, data='Different')
+        self.assertEqual(ManualPrimaryKeyTest.objects.get(id=1).data, 'Original')
+
+
 class UpdateOrCreateTransactionTests(TransactionTestCase):
     available_apps = ['get_or_create']