gh-116303: Skip test module dependent tests if test modules are disabled

Lib/test/support/__init__.py

@@ -508,7 +508,7 @@ def has_no_debug_ranges():
     try:
         import _testinternalcapi
     except ImportError:
-        raise unittest.SkipTest("_testinternalcapi required")
+        return unittest.skip("_testinternalcapi required")
     config = _testinternalcapi.get_config()
     return not bool(config['code_debug_ranges'])
 

Lib/test/support/import_helper.py

@@ -268,6 +268,18 @@ def modules_cleanup(oldmodules):
     sys.modules.update(oldmodules)
 
 
+@contextlib.contextmanager
+def isolated_modules():
+    """
+    Save modules on entry and cleanup on exit.
+    """
+    (saved,) = modules_setup()
+    try:
+        yield
+    finally:
+        modules_cleanup(saved)
+
+
 def mock_register_at_fork(func):
     # bpo-30599: Mock os.register_at_fork() when importing the random module,
     # since this function doesn't allow to unregister callbacks and would leak

Lib/test/test_embed.py

@@ -359,7 +359,6 @@ def test_simple_initialization_api(self):
         self.assertEqual(out, 'Finalized\n' * INIT_LOOPS)
 
     @support.requires_specialization
-    @unittest.skipIf(_testinternalcapi is None, "requires _testinternalcapi")
     def test_specialized_static_code_gets_unspecialized_at_Py_FINALIZE(self):
         # https://github.com/python/cpython/issues/92031
 
@@ -1596,7 +1595,6 @@ def test_global_pathconfig(self):
         # The global path configuration (_Py_path_config) must be a copy
         # of the path configuration of PyInterpreter.config (PyConfig).
         ctypes = import_helper.import_module('ctypes')
-        import _testinternalcapi
 
         def get_func(name):
             func = getattr(ctypes.pythonapi, name)

Lib/test/test_importlib/extension/test_loader.py

@@ -108,7 +108,7 @@ def setUp(self):
             )
         finder = self.machinery.FileFinder(None)
         self.spec = importlib.util.find_spec(self.name)
-        self.assertIsNotNone(self.spec)
+        assert self.spec
         self.loader = self.machinery.ExtensionFileLoader(
             self.name, self.spec.origin)
 
@@ -189,7 +189,7 @@ def setUp(self):
             )
         finder = self.machinery.FileFinder(None)
         self.spec = importlib.util.find_spec(self.name)
-        self.assertIsNotNone(self.spec)
+        assert self.spec
         self.loader = self.machinery.ExtensionFileLoader(
             self.name, self.spec.origin)
 

Lib/test/test_importlib/resources/test_files.py

@@ -70,7 +70,7 @@ def setUp(self):
         self.addCleanup(self.fixtures.close)
         self.site_dir = self.fixtures.enter_context(os_helper.temp_dir())
         self.fixtures.enter_context(import_helper.DirsOnSysPath(self.site_dir))
-        self.fixtures.enter_context(import_helper.CleanImport())
+        self.fixtures.enter_context(import_helper.isolated_modules())
 
 
 class ModulesFilesTests(SiteDir, unittest.TestCase):
@@ -79,14 +79,14 @@ def test_module_resources(self):
         A module can have resources found adjacent to the module.
         """
         spec = {
-            'mod_res.py': '',
+            'mod.py': '',
             'res.txt': 'resources are the best',
         }
         _path.build(spec, self.site_dir)
-        import mod_res
+        import mod
 
-        actual = resources.files(mod_res).joinpath('res.txt').read_text(encoding='utf-8')
-        self.assertEqual(actual, spec['res.txt'])
+        actual = resources.files(mod).joinpath('res.txt').read_text(encoding='utf-8')
+        assert actual == spec['res.txt']
 
 
 class ImplicitContextFilesTests(SiteDir, unittest.TestCase):

Misc/NEWS.d/next/Tests/2024-03-06-11-00-36.gh-issue-116307.Uij0t_.rst

@@ -0,0 +1,3 @@
+Added import helper ``isolated_modules`` as ``CleanImport`` does not remove
+modules imported during the context. Use it in importlib.resources tests to
+avoid leaving ``mod`` around to impede importlib.metadata tests.