diff options
| -rw-r--r-- | tests/prefetch_related/tests.py | 13 |
1 files changed, 12 insertions, 1 deletions
diff --git a/tests/prefetch_related/tests.py b/tests/prefetch_related/tests.py index cd763bb950..56bd64b5b9 100644 --- a/tests/prefetch_related/tests.py +++ b/tests/prefetch_related/tests.py @@ -223,7 +223,18 @@ class PrefetchRelatedTests(TestCase): self.assertIn('prefetch_related', str(cm.exception)) self.assertIn("name", str(cm.exception)) - def test_m2m_shadow(self): + def test_forward_m2m_to_attr_conflict(self): + msg = 'to_attr=authors conflicts with a field on the Book model.' + authors = Author.objects.all() + with self.assertRaisesMessage(ValueError, msg): + list(Book.objects.prefetch_related( + Prefetch('authors', queryset=authors, to_attr='authors'), + )) + # Without the ValueError, an author was deleted due to the implicit + # save of the relation assignment. + self.assertEqual(self.book1.authors.count(), 3) + + def test_reverse_m2m_to_attr_conflict(self): msg = 'to_attr=books conflicts with a field on the Author model.' poems = Book.objects.filter(title='Poems') with self.assertRaisesMessage(ValueError, msg): |