When constructing ZipReader, only append the name if the indicated module is a package.

Fixes python/cpython#121735.

Author: jaraco

importlib_resources/readers.py

@@ -34,8 +34,10 @@ def files(self):
 
 class ZipReader(abc.TraversableResources):
     def __init__(self, loader, module):
-        _, _, name = module.rpartition('.')
-        self.prefix = loader.prefix.replace('\\', '/') + name + '/'
+        self.prefix = loader.prefix.replace('\\', '/')
+        if loader.is_package(module):
+            _, _, name = module.rpartition('.')
+            self.prefix += name + '/'
         self.archive = loader.archive
 
     def open_resource(self, resource):

importlib_resources/tests/test_files.py

@@ -4,8 +4,6 @@
 import importlib
 import contextlib
 
-import pytest
-
 import importlib_resources as resources
 from ..abc import Traversable
 from . import util
@@ -93,7 +91,6 @@ class ModuleFilesDiskTests(DirectSpec, util.DiskSetup, ModulesFiles, unittest.Te
     pass
 
 
-@pytest.mark.xfail(reason="python/cpython#121735")
 class ModuleFilesZipTests(DirectSpec, util.ZipSetup, ModulesFiles, unittest.TestCase):
     pass
 
@@ -119,7 +116,6 @@ def test_implicit_files_package(self):
         """
         assert importlib.import_module('somepkg').val == 'resources are the best'
 
-    @pytest.mark.xfail(reason="python/cpython#121735")
     def test_implicit_files_submodule(self):
         """
         Without any parameter, files() will infer the location as the caller.