From c9a1aae0de95987a559b3029501a92393de57ffe Mon Sep 17 00:00:00 2001
From: "Jason R. Coombs" <jaraco@jaraco.com>
Date: Tue, 20 Aug 2024 12:11:53 -0400
Subject: [PATCH] Omit sentinel values from a namespace path.

When editable installs create sentinels, as they are not a valid directory, they're unsuitable for constructing a `MultiplexedPath`. Filter them out.

Fixes #311
---
 importlib_resources/readers.py          | 13 +++++++++----
 importlib_resources/tests/test_files.py |  3 ---
 newsfragments/311.bugfix.rst            |  1 +
 3 files changed, 10 insertions(+), 7 deletions(-)
 create mode 100644 newsfragments/311.bugfix.rst

diff --git a/importlib_resources/readers.py b/importlib_resources/readers.py
index abfcde7..89f70de 100644
--- a/importlib_resources/readers.py
+++ b/importlib_resources/readers.py
@@ -5,6 +5,7 @@
 import operator
 import re
 import warnings
+from typing import Optional
 
 from . import abc
 
@@ -135,19 +136,23 @@ class NamespaceReader(abc.TraversableResources):
     def __init__(self, namespace_path):
         if 'NamespacePath' not in str(namespace_path):
             raise ValueError('Invalid path')
-        self.path = MultiplexedPath(*map(self._resolve, namespace_path))
+        self.path = MultiplexedPath(*filter(bool, map(self._resolve, namespace_path)))
 
     @classmethod
-    def _resolve(cls, path_str) -> abc.Traversable:
+    def _resolve(cls, path_str) -> Optional[abc.Traversable]:
         r"""
         Given an item from a namespace path, resolve it to a Traversable.
 
         path_str might be a directory on the filesystem or a path to a
         zipfile plus the path within the zipfile, e.g. ``/foo/bar`` or
         ``/foo/baz.zip/inner_dir`` or ``foo\baz.zip\inner_dir\sub``.
+
+        path_str might also be a sentinel used by editable packages to
+        trigger other behaviors (see python/importlib_resources#311).
+        In that case, return None.
         """
-        (dir,) = (cand for cand in cls._candidate_paths(path_str) if cand.is_dir())
-        return dir
+        dirs = (cand for cand in cls._candidate_paths(path_str) if cand.is_dir())
+        return next(dirs, None)
 
     @classmethod
     def _candidate_paths(cls, path_str):
diff --git a/importlib_resources/tests/test_files.py b/importlib_resources/tests/test_files.py
index c07975c..412a44d 100644
--- a/importlib_resources/tests/test_files.py
+++ b/importlib_resources/tests/test_files.py
@@ -8,8 +8,6 @@
 import importlib
 import contextlib
 
-import pytest
-
 import importlib_resources as resources
 from ..abc import Traversable
 from . import util
@@ -62,7 +60,6 @@ class OpenZipTests(FilesTests, util.ZipSetup, unittest.TestCase):
 class OpenNamespaceTests(FilesTests, util.DiskSetup, unittest.TestCase):
     MODULE = 'namespacedata01'
 
-    @pytest.mark.xfail(reason="#311")
     def test_non_paths_in_dunder_path(self):
         """
         Non-path items in a namespace package's ``__path__`` are ignored.
diff --git a/newsfragments/311.bugfix.rst b/newsfragments/311.bugfix.rst
new file mode 100644
index 0000000..56655f7
--- /dev/null
+++ b/newsfragments/311.bugfix.rst
@@ -0,0 +1 @@
+Omit sentinel values from a namespace path.
\ No newline at end of file