1 files changed, 47 insertions, 0 deletions
diff --git a/tests/foreign_object/test_empty_join.py b/tests/foreign_object/test_empty_join.py
new file mode 100644
index 0000000000..a043595ce2
--- /dev/null
+++ b/tests/foreign_object/test_empty_join.py
@@ -0,0 +1,47 @@
+from django.test import TestCase
+
+from .models import SlugPage
+
+
+class RestrictedConditionsTests(TestCase):
+    def setUp(self):
+        slugs = [
+            'a',
+            'a/a',
+            'a/b',
+            'a/b/a',
+            'x',
+            'x/y/z',
+        ]
+        SlugPage.objects.bulk_create([SlugPage(slug=slug) for slug in slugs])
+
+    def test_restrictions_with_no_joining_columns(self):
+        """
+        Test that it's possible to create a working related field that doesn't
+        use any joining columns, as long as an extra restriction is supplied.
+        """
+        a = SlugPage.objects.get(slug='a')
+        self.assertListEqual(
+            [p.slug for p in SlugPage.objects.filter(ascendants=a)],
+            ['a', 'a/a', 'a/b', 'a/b/a'],
+        )
+        self.assertEqual(
+            [p.slug for p in a.descendants.all()],
+            ['a', 'a/a', 'a/b', 'a/b/a'],
+        )
+
+        aba = SlugPage.objects.get(slug='a/b/a')
+        self.assertListEqual(
+            [p.slug for p in SlugPage.objects.filter(descendants__in=[aba])],
+            ['a', 'a/b', 'a/b/a'],
+        )
+        self.assertListEqual(
+            [p.slug for p in aba.ascendants.all()],
+            ['a', 'a/b', 'a/b/a'],
+        )
+
+    def test_empty_join_conditions(self):
+        x = SlugPage.objects.get(slug='x')
+        message = "Join generated an empty ON clause."
+        with self.assertRaisesMessage(ValueError, message):
+            list(SlugPage.objects.filter(containers=x))