[3.12] GH-115979: update test_importlib to work under WASI SDK 21 (GH-116754) (GH-116759)

GH-115979: update test_importlib to work under WASI SDK 21 (GH-116754)
(cherry picked from commit 61733a2fb9dc36d2246d922146a3462a2248832d)

Co-authored-by: Brett Cannon <brett@python.org>

7 files changed, 44 insertions, 28 deletions

diff --git a/Lib/test/test_importlib/extension/test_case_sensitivity.py b/Lib/test/test_importlib/extension/test_case_sensitivity.py
index 0bb74ff..4031162 100644
--- a/Lib/test/test_importlib/extension/test_case_sensitivity.py
+++ b/Lib/test/test_importlib/extension/test_case_sensitivity.py
@@ -8,7 +8,8 @@ importlib = util.import_importlib('importlib')
 machinery = util.import_importlib('importlib.machinery')
 
 
-@unittest.skipIf(util.EXTENSIONS.filename is None, f'{util.EXTENSIONS.name} not available')
+@unittest.skipIf(util.EXTENSIONS is None or util.EXTENSIONS.filename is None,
+                 'dynamic loading not supported or test module not available')
 @util.case_insensitive_tests
 class ExtensionModuleCaseSensitivityTest(util.CASEOKTestBase):
 
diff --git a/Lib/test/test_importlib/extension/test_finder.py b/Lib/test/test_importlib/extension/test_finder.py
index 1d5b6e7..3de1209 100644
--- a/Lib/test/test_importlib/extension/test_finder.py
+++ b/Lib/test/test_importlib/extension/test_finder.py
@@ -11,7 +11,7 @@ class FinderTests(abc.FinderTests):
     """Test the finder for extension modules."""
 
     def setUp(self):
-        if not self.machinery.EXTENSION_SUFFIXES:
+        if not self.machinery.EXTENSION_SUFFIXES or not util.EXTENSIONS:
             raise unittest.SkipTest("Requires dynamic loading support.")
         if util.EXTENSIONS.name in sys.builtin_module_names:
             raise unittest.SkipTest(
diff --git a/Lib/test/test_importlib/extension/test_loader.py b/Lib/test/test_importlib/extension/test_loader.py
index 1b5a8ba..12f9e43 100644
--- a/Lib/test/test_importlib/extension/test_loader.py
+++ b/Lib/test/test_importlib/extension/test_loader.py
@@ -19,7 +19,7 @@ class LoaderTests:
     """Test ExtensionFileLoader."""
 
     def setUp(self):
-        if not self.machinery.EXTENSION_SUFFIXES:
+        if not self.machinery.EXTENSION_SUFFIXES or not util.EXTENSIONS:
             raise unittest.SkipTest("Requires dynamic loading support.")
         if util.EXTENSIONS.name in sys.builtin_module_names:
             raise unittest.SkipTest(
@@ -101,7 +101,7 @@ class SinglePhaseExtensionModuleTests(abc.LoaderTests):
     # Test loading extension modules without multi-phase initialization.
 
     def setUp(self):
-        if not self.machinery.EXTENSION_SUFFIXES:
+        if not self.machinery.EXTENSION_SUFFIXES or not util.EXTENSIONS:
             raise unittest.SkipTest("Requires dynamic loading support.")
         self.name = '_testsinglephase'
         if self.name in sys.builtin_module_names:
@@ -182,7 +182,7 @@ class MultiPhaseExtensionModuleTests(abc.LoaderTests):
     # Test loading extension modules with multi-phase initialization (PEP 489).
 
     def setUp(self):
-        if not self.machinery.EXTENSION_SUFFIXES:
+        if not self.machinery.EXTENSION_SUFFIXES or not util.EXTENSIONS:
             raise unittest.SkipTest("Requires dynamic loading support.")
         self.name = '_testmultiphase'
         if self.name in sys.builtin_module_names:
diff --git a/Lib/test/test_importlib/extension/test_path_hook.py b/Lib/test/test_importlib/extension/test_path_hook.py
index ec9644d..314a635 100644
--- a/Lib/test/test_importlib/extension/test_path_hook.py
+++ b/Lib/test/test_importlib/extension/test_path_hook.py
@@ -5,6 +5,8 @@ machinery = util.import_importlib('importlib.machinery')
 import unittest
 
 
+@unittest.skipIf(util.EXTENSIONS is None or util.EXTENSIONS.filename is None,
+                 'dynamic loading not supported or test module not available')
 class PathHookTests:
 
     """Test the path hook for extension modules."""
diff --git a/Lib/test/test_importlib/test_spec.py b/Lib/test/test_importlib/test_spec.py
index 80aa360..0231892 100644
--- a/Lib/test/test_importlib/test_spec.py
+++ b/Lib/test/test_importlib/test_spec.py
@@ -502,7 +502,8 @@ class FactoryTests:
         self.assertEqual(spec.loader, self.fileloader)
         self.assertEqual(spec.origin, self.path)
         self.assertIs(spec.loader_state, None)
-        self.assertEqual(spec.submodule_search_locations, [os.getcwd()])
+        location = cwd if (cwd := os.getcwd()) != '/' else ''
+        self.assertEqual(spec.submodule_search_locations, [location])
         self.assertEqual(spec.cached, self.cached)
         self.assertTrue(spec.has_location)
 
@@ -601,7 +602,8 @@ class FactoryTests:
         self.assertEqual(spec.loader, self.fileloader)
         self.assertEqual(spec.origin, self.path)
         self.assertIs(spec.loader_state, None)
-        self.assertEqual(spec.submodule_search_locations, [os.getcwd()])
+        location = cwd if (cwd := os.getcwd()) != '/' else ''
+        self.assertEqual(spec.submodule_search_locations, [location])
         self.assertEqual(spec.cached, self.cached)
         self.assertTrue(spec.has_location)
 
@@ -626,7 +628,8 @@ class FactoryTests:
         self.assertEqual(spec.loader, self.pkgloader)
         self.assertEqual(spec.origin, self.path)
         self.assertIs(spec.loader_state, None)
-        self.assertEqual(spec.submodule_search_locations, [os.getcwd()])
+        location = cwd if (cwd := os.getcwd()) != '/' else ''
+        self.assertEqual(spec.submodule_search_locations, [location])
         self.assertEqual(spec.cached, self.cached)
         self.assertTrue(spec.has_location)
 
diff --git a/Lib/test/test_importlib/test_util.py b/Lib/test/test_importlib/test_util.py
index 217c1ad..e018af2 100644
--- a/Lib/test/test_importlib/test_util.py
+++ b/Lib/test/test_importlib/test_util.py
@@ -577,7 +577,7 @@ class PEP3147Tests:
         with util.temporary_pycache_prefix(pycache_prefix):
             self.assertEqual(
                 self.util.cache_from_source(path, optimization=''),
-                expect)
+                os.path.normpath(expect))
 
     @unittest.skipIf(sys.implementation.cache_tag is None,
                      'requires sys.implementation.cache_tag to not be None')
diff --git a/Lib/test/test_importlib/util.py b/Lib/test/test_importlib/util.py
index c25be09..a900cc1 100644
--- a/Lib/test/test_importlib/util.py
+++ b/Lib/test/test_importlib/util.py
@@ -6,6 +6,7 @@ from importlib import machinery, util, invalidate_caches
 import marshal
 import os
 import os.path
+from test import support
 from test.support import import_helper
 from test.support import os_helper
 import unittest
@@ -22,25 +23,34 @@ if 'errno' in sys.builtin_module_names:
 if 'importlib' not in sys.builtin_module_names:
     BUILTINS.bad_name = 'importlib'
 
-EXTENSIONS = types.SimpleNamespace()
-EXTENSIONS.path = None
-EXTENSIONS.ext = None
-EXTENSIONS.filename = None
-EXTENSIONS.file_path = None
-EXTENSIONS.name = '_testsinglephase'
-
-def _extension_details():
-    global EXTENSIONS
-    for path in sys.path:
-        for ext in machinery.EXTENSION_SUFFIXES:
-            filename = EXTENSIONS.name + ext
-            file_path = os.path.join(path, filename)
-            if os.path.exists(file_path):
-                EXTENSIONS.path = path
-                EXTENSIONS.ext = ext
-                EXTENSIONS.filename = filename
-                EXTENSIONS.file_path = file_path
-                return
+if support.is_wasi:
+    # dlopen() is a shim for WASI as of WASI SDK which fails by default.
+    # We don't provide an implementation, so tests will fail.
+    # But we also don't want to turn off dynamic loading for those that provide
+    # a working implementation.
+    def _extension_details():
+        global EXTENSIONS
+        EXTENSIONS = None
+else:
+    EXTENSIONS = types.SimpleNamespace()
+    EXTENSIONS.path = None
+    EXTENSIONS.ext = None
+    EXTENSIONS.filename = None
+    EXTENSIONS.file_path = None
+    EXTENSIONS.name = '_testsinglephase'
+
+    def _extension_details():
+        global EXTENSIONS
+        for path in sys.path:
+            for ext in machinery.EXTENSION_SUFFIXES:
+                filename = EXTENSIONS.name + ext
+                file_path = os.path.join(path, filename)
+                if os.path.exists(file_path):
+                    EXTENSIONS.path = path
+                    EXTENSIONS.ext = ext
+                    EXTENSIONS.filename = filename
+                    EXTENSIONS.file_path = file_path
+                    return
 
 _extension_details()