Fixed #31061 -- Ignored positional args in django.urls.resolve() when all optional named parameters are missing.

Regression in 76b993a117b61c41584e95149a67d8a1e9f49dd1.

Thanks Claude Paroz for the report and Carlton Gibson for reviews.

2 files changed, 15 insertions, 0 deletions

diff --git a/tests/urlpatterns/path_urls.py b/tests/urlpatterns/path_urls.py
index b40801b39d..afc15f30af 100644
--- a/tests/urlpatterns/path_urls.py
+++ b/tests/urlpatterns/path_urls.py
@@ -12,6 +12,11 @@ urlpatterns = [
     path('included_urls/', include('urlpatterns.included_urls')),
     re_path(r'^regex/(?P<pk>[0-9]+)/$', views.empty_view, name='regex'),
     re_path(r'^regex_optional/(?P<arg1>\d+)/(?:(?P<arg2>\d+)/)?', views.empty_view, name='regex_optional'),
+    re_path(
+        r'^regex_only_optional/(?:(?P<arg1>\d+)/)?',
+        views.empty_view,
+        name='regex_only_optional',
+    ),
     path('', include('urlpatterns.more_urls')),
     path('<lang>/<path:url>/', views.empty_view, name='lang-and-path'),
 ]
diff --git a/tests/urlpatterns/tests.py b/tests/urlpatterns/tests.py
index 92c4e6399e..b149e0d512 100644
--- a/tests/urlpatterns/tests.py
+++ b/tests/urlpatterns/tests.py
@@ -68,6 +68,16 @@ class SimplifiedURLTests(SimpleTestCase):
                     r'^regex_optional/(?P<arg1>\d+)/(?:(?P<arg2>\d+)/)?',
                 )
 
+    def test_re_path_with_missing_optional_parameter(self):
+        match = resolve('/regex_only_optional/')
+        self.assertEqual(match.url_name, 'regex_only_optional')
+        self.assertEqual(match.kwargs, {})
+        self.assertEqual(match.args, ())
+        self.assertEqual(
+            match.route,
+            r'^regex_only_optional/(?:(?P<arg1>\d+)/)?',
+        )
+
     def test_path_lookup_with_inclusion(self):
         match = resolve('/included_urls/extra/something/')
         self.assertEqual(match.url_name, 'inner-extra')