Skip articles whose slug would write .html.

pelican/contents.py

@@ -198,6 +198,18 @@ class Content:
             )
             return False
 
+        # "{slug}.html" with an empty slug becomes ".html", which the
+        # development server then treats as the site root.
+        name = os.path.basename(str(self.save_as).replace("\\", "/"))
+        if name in {".html", ".", ""}:
+            logger.warning(
+                "Skipping %s: slug %r produces an invalid output filename %r",
+                self,
+                getattr(self, "slug", ""),
+                self.save_as,
+            )
+            return False
+
         return True
 
     def _has_valid_status(self) -> bool:

pelican/tests/test_contents.py

@@ -811,6 +811,18 @@ class TestArticle(TestBase):
         article = Article(**article_kwargs)
         self.assertTrue(article._has_valid_save_as())
 
+    def test_symbol_only_title_does_not_write_dot_html(self):
+        settings = get_settings()
+        article_kwargs = self._copy_page_kwargs()
+        article_kwargs["metadata"]["title"] = "~"
+        article_kwargs["metadata"]["date"] = datetime.datetime(2005, 2, 4, 18, 59)
+        article_kwargs["settings"] = settings
+        article = Article(**article_kwargs)
+        self.assertEqual(article.slug, "")
+        self.assertEqual(article.save_as, ".html")
+        self.assertFalse(article._has_valid_save_as())
+        self.assertFalse(article.is_valid())
+
 
 class TestStatic(LoggedTestCase):
     def setUp(self):