1 files changed, 42 insertions, 0 deletions
diff --git a/tests/null_fk_ordering/tests.py b/tests/null_fk_ordering/tests.py
new file mode 100644
index 0000000000..aea969de4f
--- /dev/null
+++ b/tests/null_fk_ordering/tests.py
@@ -0,0 +1,42 @@
+from __future__ import absolute_import
+
+from django.test import TestCase
+
+from .models import Author, Article, SystemInfo, Forum, Post, Comment
+
+
+class NullFkOrderingTests(TestCase):
+
+    def test_ordering_across_null_fk(self):
+        """
+        Regression test for #7512
+
+        ordering across nullable Foreign Keys shouldn't exclude results
+        """
+        author_1 = Author.objects.create(name='Tom Jones')
+        author_2 = Author.objects.create(name='Bob Smith')
+        article_1 = Article.objects.create(title='No author on this article')
+        article_2 = Article.objects.create(author=author_1, title='This article written by Tom Jones')
+        article_3 = Article.objects.create(author=author_2, title='This article written by Bob Smith')
+
+        # We can't compare results directly (since different databases sort NULLs to
+        # different ends of the ordering), but we can check that all results are
+        # returned.
+        self.assertTrue(len(list(Article.objects.all())) == 3)
+
+        s = SystemInfo.objects.create(system_name='System Info')
+        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')
+        s2 = SystemInfo.objects.create(system_name='More System Info')
+        f2 = Forum.objects.create(system_info=s2, forum_name='Second forum')
+        p2 = Post.objects.create(forum=f2, title='Second Post')
+        c3 = Comment.objects.create(comment_text='Another first comment')
+        c4 = Comment.objects.create(post=p2, comment_text='Another second comment')
+
+        # We have to test this carefully. Some databases sort NULL values before
+        # everything else, some sort them afterwards. So we extract the ordered list
+        # and check the length. Before the fix, this list was too short (some values
+        # were omitted).
+        self.assertTrue(len(list(Comment.objects.all())) == 4)