ci(changelog): suggest <type>.md when an added file has no type

scripts/ci/check-changelog.py

@@ -172,7 +172,10 @@ def pull_request_problems(number: int, title: str, base: str, files: List[Change
         if changed.status != "added" or owner is None or changed.filename[len(FRAGMENTS) + 1:] in IGNORED:
             continue
         if owner != str(number) and owner not in removed:
-            rest = changed.filename[len(FRAGMENTS) + 1:].partition(".")[2] or "<type>.md"
+            rest = changed.filename[len(FRAGMENTS) + 1:].partition(".")[2]
+            # A rest with no dot holds no type, so towncrier would refuse it as a suffix.
+            if "." not in rest:
+                rest = "<type>.md"
             problems.append(f"{changed.filename} is not named for this pull request. "
                             f"Name it {FRAGMENTS}/{number}.{rest}")
     return problems

scripts/ci/test_check_changelog.py

@@ -238,9 +238,12 @@ def test_an_orphan_fragment_on_main_is_refused(self):
         problems = self.problems([changed("changelog.d/+theme.fixed.md")])
         self.assertIn("Name it changelog.d/3600.fixed.md", problems[0])
 
-    def test_a_file_that_is_not_a_fragment_is_refused(self):
-        self.assertEqual(len(self.problems([changed("changelog.d/notes.txt")])), 1)
-        self.assertIn("Name it changelog.d/3600.<type>.md", self.problems([changed("changelog.d/notes")])[0])
+    def test_a_file_that_is_not_a_fragment_gets_the_type_placeholder(self):
+        for name in ("notes.txt", "README.md", "notes"):
+            with self.subTest(name=name):
+                problems = self.problems([changed(f"changelog.d/{name}")])
+                self.assertEqual(len(problems), 1)
+                self.assertIn("Name it changelog.d/3600.<type>.md", problems[0])
 
     def test_gitkeep_is_not_a_fragment(self):
         self.assertEqual(self.problems([changed("changelog.d/.gitkeep")]), [])