Fixed #28497 -- Restored the ability to use sliced QuerySets with __exact.

Regression in ec50937bcbe160e658ef881021402e156beb0eaf.

Thanks Simon Charette for review.

1 files changed, 22 insertions, 0 deletions

diff --git a/tests/lookup/tests.py b/tests/lookup/tests.py
index 7b08c778df..0161782dbe 100644
--- a/tests/lookup/tests.py
+++ b/tests/lookup/tests.py
@@ -848,6 +848,28 @@ class LookupTests(TestCase):
         self.assertTrue(Season.objects.filter(nulled_text_field__nulled__exact=None))
         self.assertTrue(Season.objects.filter(nulled_text_field__nulled=None))
 
+    def test_exact_sliced_queryset_limit_one(self):
+        self.assertCountEqual(
+            Article.objects.filter(author=Author.objects.all()[:1]),
+            [self.a1, self.a2, self.a3, self.a4]
+        )
+
+    def test_exact_sliced_queryset_limit_one_offset(self):
+        self.assertCountEqual(
+            Article.objects.filter(author=Author.objects.all()[1:2]),
+            [self.a5, self.a6, self.a7]
+        )
+
+    def test_exact_sliced_queryset_not_limited_to_one(self):
+        msg = (
+            'The QuerySet value for an exact lookup must be limited to one '
+            'result using slicing.'
+        )
+        with self.assertRaisesMessage(ValueError, msg):
+            list(Article.objects.filter(author=Author.objects.all()[:2]))
+        with self.assertRaisesMessage(ValueError, msg):
+            list(Article.objects.filter(author=Author.objects.all()[1:]))
+
     def test_custom_field_none_rhs(self):
         """
         __exact=value is transformed to __isnull=True if Field.get_prep_value()