[tests] run subtest with test_unconnected_with_repo

run subtest with pagegenerators_tests within
TestUnconnectedPageGenerator.test_unconnected_with_repo to
have more tests and a more informative error message if it fails.

Change-Id: I93a8f08e14226a3efc1290786e4f6311a5f0dd10
---
M tests/pagegenerators_tests.py
1 file changed, 17 insertions(+), 4 deletions(-)

diff --git a/tests/pagegenerators_tests.py b/tests/pagegenerators_tests.py
index 6c2b890..8b8c05a 100755
--- a/tests/pagegenerators_tests.py
+++ b/tests/pagegenerators_tests.py
@@ -1687,11 +1687,11 @@
         self.assertLessEqual(len(pages), 3)
 
         site = self.site.data_repository()
-        pattern = (r'Page '
-                   r'\[\[({site.sitename}:|{site.code}:)-1\]\]'
-                   r" doesn't exist\.".format(site=site))
+        pattern = (fr'Page \[\[({site.sitename}:|{site.code}:)-1\]\]'
+                   r" doesn't exist\.")
         for page in pages:
-            with self.assertRaisesRegex(NoPageError, pattern):
+            with self.subTest(page=page), self.assertRaisesRegex(
+                    NoPageError, pattern):
                 page.data_item()
 
     def test_unconnected_without_repo(self):

