1 files changed, 69 insertions, 0 deletions
diff --git a/tests/null_fk/tests.py b/tests/null_fk/tests.py
new file mode 100644
index 0000000000..96a06b6769
--- /dev/null
+++ b/tests/null_fk/tests.py
@@ -0,0 +1,69 @@
+from __future__ import absolute_import,  unicode_literals
+
+from django.db.models import Q
+from django.test import TestCase
+
+from .models import (SystemDetails, Item, PropertyValue, SystemInfo, Forum,
+    Post, Comment)
+
+
+class NullFkTests(TestCase):
+
+    def test_null_fk(self):
+        d = SystemDetails.objects.create(details='First details')
+        s = SystemInfo.objects.create(system_name='First forum', system_details=d)
+        f = Forum.objects.create(system_info=s, forum_name='First forum')
+        p = Post.objects.create(forum=f, title='First Post')
+        c1 = Comment.objects.create(post=p, comment_text='My first comment')
+        c2 = Comment.objects.create(comment_text='My second comment')
+
+        # Starting from comment, make sure that a .select_related(...) with a specified
+        # set of fields will properly LEFT JOIN multiple levels of NULLs (and the things
+        # that come after the NULLs, or else data that should exist won't). Regression
+        # test for #7369.
+        c = Comment.objects.select_related().get(id=c1.id)
+        self.assertEqual(c.post, p)
+        self.assertEqual(Comment.objects.select_related().get(id=c2.id).post, None)
+
+        self.assertQuerysetEqual(
+            Comment.objects.select_related('post__forum__system_info').all(),
+            [
+                (c1.id, 'My first comment', '<Post: First Post>'),
+                (c2.id, 'My second comment', 'None')
+            ],
+            transform = lambda c: (c.id, c.comment_text, repr(c.post))
+        )
+
+        # Regression test for #7530, #7716.
+        self.assertTrue(Comment.objects.select_related('post').filter(post__isnull=True)[0].post is None)
+
+        self.assertQuerysetEqual(
+            Comment.objects.select_related('post__forum__system_info__system_details'),
+            [
+                (c1.id, 'My first comment', '<Post: First Post>'),
+                (c2.id, 'My second comment', 'None')
+            ],
+            transform = lambda c: (c.id, c.comment_text, repr(c.post))
+        )
+
+    def test_combine_isnull(self):
+        item = Item.objects.create(title='Some Item')
+        pv = PropertyValue.objects.create(label='Some Value')
+        item.props.create(key='a', value=pv)
+        item.props.create(key='b') # value=NULL
+        q1 = Q(props__key='a', props__value=pv)
+        q2 = Q(props__key='b', props__value__isnull=True)
+
+        # Each of these individually should return the item.
+        self.assertEqual(Item.objects.get(q1), item)
+        self.assertEqual(Item.objects.get(q2), item)
+
+        # Logically, qs1 and qs2, and qs3 and qs4 should be the same.
+        qs1 = Item.objects.filter(q1) & Item.objects.filter(q2)
+        qs2 = Item.objects.filter(q2) & Item.objects.filter(q1)
+        qs3 = Item.objects.filter(q1) | Item.objects.filter(q2)
+        qs4 = Item.objects.filter(q2) | Item.objects.filter(q1)
+
+        # Regression test for #15823.
+        self.assertEqual(list(qs1), list(qs2))
+        self.assertEqual(list(qs3), list(qs4))