Using pyfakefs, capture failure when an item on sys.path is inaccessible. Ref #94.

Author: jaraco

importlib_metadata/tests/test_main.py

@@ -1,15 +1,16 @@
 # coding: utf-8
 from __future__ import unicode_literals
 
-import os
 import re
 import json
 import pickle
 import textwrap
+import unittest
 import importlib
-import unittest.mock
 import importlib_metadata
 
+import pyfakefs.fake_filesystem_unittest as ffs
+
 from . import fixtures
 from .. import (
     Distribution, EntryPoint, MetadataPathFinder,
@@ -205,28 +206,20 @@ def test_discovery(self):
         importlib_metadata.distributions()
 
 
-class InaccessibleSysPath(fixtures.OnSysPath, unittest.TestCase):
+class InaccessibleSysPath(fixtures.OnSysPath, ffs.TestCase):
     site_dir = '/access-denied'
 
-    def listdir(self, target, orig=os.listdir):
-        """
-        Fake listdir raising an exception when access is denied.
-        """
-        if target == self.site_dir:
-            raise OSError(13, 'Permission denied')
-        return orig(target)
-
     def setUp(self):
         super(InaccessibleSysPath, self).setUp()
-        self.fixtures.enter_context(
-            unittest.mock.patch('os.listdir', self.listdir))
+        self.setUpPyfakefs()
+        self.fs.create_dir(self.site_dir, perm_bits=000)
 
     def test_discovery(self):
         """
         Discovering distributions should succeed even if
         there is an invalid path on sys.path.
         """
-        importlib_metadata.distributions()
+        list(importlib_metadata.distributions())
 
 
 class TestEntryPoints(unittest.TestCase):

tox.ini

@@ -28,6 +28,7 @@ passenv =
 deps =
     cov,diffcov: coverage>=4.5
     diffcov: diff_cover
+    pyfakefs
 setenv =
     cov: COVERAGE_PROCESS_START={[coverage]rcfile}
     cov: COVERAGE_OPTIONS="-p"