Refs #31282 -- Clarified M2O add/remove/set with PK behaviour.

Improved error message for remove() and added tests.

1 files changed, 11 insertions, 0 deletions

diff --git a/tests/many_to_one/tests.py b/tests/many_to_one/tests.py
index d769b206b9..76ef4921dd 100644
--- a/tests/many_to_one/tests.py
+++ b/tests/many_to_one/tests.py
@@ -733,3 +733,14 @@ class ManyToOneTests(TestCase):
         child = parent.to_field_children.get()
         with self.assertNumQueries(0):
             self.assertIs(child.parent, parent)
+
+    def test_add_remove_set_by_pk_raises(self):
+        usa = Country.objects.create(name='United States')
+        chicago = City.objects.create(name='Chicago')
+        msg = "'City' instance expected, got %s" % chicago.pk
+        with self.assertRaisesMessage(TypeError, msg):
+            usa.cities.add(chicago.pk)
+        with self.assertRaisesMessage(TypeError, msg):
+            usa.cities.remove(chicago.pk)
+        with self.assertRaisesMessage(TypeError, msg):
+            usa.cities.set([chicago.pk])