--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/parts/django/tests/regressiontests/null_queries/tests.py	Sat Jan 08 11:20:57 2011 +0530
@@ -0,0 +1,69 @@
+from django.test import TestCase
+from django.core.exceptions import FieldError
+
+from regressiontests.null_queries.models import *
+
+
+class NullQueriesTests(TestCase):
+
+    def test_none_as_null(self):
+        """
+        Regression test for the use of None as a query value.
+
+        None is interpreted as an SQL NULL, but only in __exact queries.
+        Set up some initial polls and choices
+        """
+        p1 = Poll(question='Why?')
+        p1.save()
+        c1 = Choice(poll=p1, choice='Because.')
+        c1.save()
+        c2 = Choice(poll=p1, choice='Why Not?')
+        c2.save()
+
+        # Exact query with value None returns nothing ("is NULL" in sql,
+        # but every 'id' field has a value).
+        self.assertQuerysetEqual(Choice.objects.filter(choice__exact=None), [])
+
+        # Excluding the previous result returns everything.
+        self.assertQuerysetEqual(
+                Choice.objects.exclude(choice=None).order_by('id'),
+                [
+                    '<Choice: Choice: Because. in poll Q: Why? >',
+                    '<Choice: Choice: Why Not? in poll Q: Why? >'
+                ]
+        )
+
+        # Valid query, but fails because foo isn't a keyword
+        self.assertRaises(FieldError, Choice.objects.filter, foo__exact=None)
+
+        # Can't use None on anything other than __exact
+        self.assertRaises(ValueError, Choice.objects.filter, id__gt=None)
+
+        # Can't use None on anything other than __exact
+        self.assertRaises(ValueError, Choice.objects.filter, foo__gt=None)
+
+        # Related managers use __exact=None implicitly if the object hasn't been saved.
+        p2 = Poll(question="How?")
+        self.assertEquals(repr(p2.choice_set.all()), '[]')
+
+    def test_reverse_relations(self):
+        """
+        Querying across reverse relations and then another relation should
+        insert outer joins correctly so as not to exclude results.
+        """
+        obj = OuterA.objects.create()
+        self.assertQuerysetEqual(
+            OuterA.objects.filter(inner__second=None),
+            ['<OuterA: OuterA object>']
+        )
+        self.assertQuerysetEqual(
+            OuterA.objects.filter(inner__second__data=None),
+            ['<OuterA: OuterA object>']
+        )
+
+        inner_obj = Inner.objects.create(first=obj)
+        self.assertQuerysetEqual(
+            Inner.objects.filter(first__inner__second=None),
+            ['<Inner: Inner object>']
+        )
+