error if the wiki article file name is included

tests/test_articles/wiki/malformed_link/en.md

@@ -1 +1,3 @@
 [Malformed link](//example.com)
+
+[Erroneously includes article file name](/wiki/malformed_link/en.md)

tests/test_articles/wiki/not_found/en.md

@@ -6,6 +6,6 @@
 
 ![][flag_AA] No flag here
 
-[Error only when case-sensitive](/wiki/NOT_FOUND/en.md)
+[Error only when case-sensitive](/wiki/NOT_FOUND)
 
 [flag_AA]: /wiki/shared/flag/AA.gif

tests/test_link_checker.py

@@ -117,6 +117,19 @@ def test__invalid_absolute_link(self, root):
             )
             assert isinstance(error, error_types.LinkNotFoundError)
 
+    def test__invalid_link_with_filename(self, root):
+        utils.create_files(
+            root,
+            ('wiki/Another_article/en.md', '# Another article')
+        )
+
+        link = link_parser.find_link("This link [shouldn't include the filename](/wiki/Another_article/en.md).")
+        assert link
+        error = link_checker.check_link(
+            article=dummy_article('does/not/matter'), link=link, redirects={}, references={}, all_articles={}
+        )
+        assert isinstance(error, error_types.MalformedLinkError)
+
     def test__valid_reference(self, root):
         utils.create_files(
             root,

wikitools/errors.py

@@ -28,16 +28,17 @@ def pos(self):
 
 class MalformedLinkError(
     LinkError,
-    collections.namedtuple('MalformedLinkError', 'link')
+    collections.namedtuple('MalformedLinkError', 'link reason')
 ):
     """
-    An error indicating an erroneous link (for example, with several leading slashes).
+    An error indicating an erroneous link (for example, with several leading slashes, or including the wiki article file name).
     """
 
     link: link_parser.Link
+    reason: str
 
     def __repr__(self):
-        return f'Incorrect link structure (typo?): "{self.link.raw_location}"'
+        return f'"{self.link.raw_location}": {self.reason}'
 
 
 class LinkNotFoundError(

wikitools/link_checker.py

@@ -6,6 +6,7 @@
 from wikitools import redirect_parser, reference_parser, errors, link_parser, article_parser
 from wikitools import console
 from wikitools.file_utils import exists_case_sensitive, exists_case_insensitive
+from wikitools.file_utils import is_article
 
 
 class PathType:
@@ -84,14 +85,17 @@ def get_repo_path(
     if parsed_location.scheme:
         return None
 
+    if is_article(parsed_location.path):
+        return errors.MalformedLinkError(link, "wiki links must not include the article file name")
+
     if parsed_location.path.startswith("/"):
         # absolute wiki link
         path = pathlib.Path(parsed_location.path[1:])
         return RepositoryPath(path_type=PathType.WIKI, path=path, fragment=parsed_location.fragment)
 
     # domain is non-empty, but the link is internal?
     if parsed_location.netloc:
-        return errors.MalformedLinkError(link)
+        return errors.MalformedLinkError(link, "incorrect link structure (typo?)")
 
     # relative wiki link
     path = current_article / parsed_location.path