gh-109625: Move _ready_to_import() from test_import to support.import_helper (#109626)

Lib/test/test_import/__init__.py

@@ -30,9 +30,10 @@ from test.support import (
     STDLIB_DIR, swap_attr, swap_item, cpython_only, is_emscripten,
     is_wasi, run_in_subinterp, run_in_subinterp_with_config, Py_TRACE_REFS)
 from test.support.import_helper import (
-    forget, make_legacy_pyc, unlink, unload, DirsOnSysPath, CleanImport)
+    forget, make_legacy_pyc, unlink, unload, ready_to_import,
+    DirsOnSysPath, CleanImport)
 from test.support.os_helper import (
-    TESTFN, rmtree, temp_umask, TESTFN_UNENCODABLE, temp_dir)
+    TESTFN, rmtree, temp_umask, TESTFN_UNENCODABLE)
 from test.support import script_helper
 from test.support import threading_helper
 from test.test_importlib.util import uncache
@@ -125,27 +126,6 @@ def no_rerun(reason):
     return deco
 
 
-@contextlib.contextmanager
-def _ready_to_import(name=None, source=""):
-    # sets up a temporary directory and removes it
-    # creates the module file
-    # temporarily clears the module from sys.modules (if any)
-    # reverts or removes the module when cleaning up
-    name = name or "spam"
-    with temp_dir() as tempdir:
-        path = script_helper.make_script(tempdir, name, source)
-        old_module = sys.modules.pop(name, None)
-        try:
-            sys.path.insert(0, tempdir)
-            yield name, path
-            sys.path.remove(tempdir)
-        finally:
-            if old_module is not None:
-                sys.modules[name] = old_module
-            elif name in sys.modules:
-                del sys.modules[name]
-
-
 if _testsinglephase is not None:
     def restore__testsinglephase(*, _orig=_testsinglephase):
         # We started with the module imported and want to restore
@@ -401,7 +381,7 @@ class ImportTests(unittest.TestCase):
 
     def test_from_import_star_invalid_type(self):
         import re
-        with _ready_to_import() as (name, path):
+        with ready_to_import() as (name, path):
             with open(path, 'w', encoding='utf-8') as f:
                 f.write("__all__ = [b'invalid_type']")
             globals = {}
@@ -410,7 +390,7 @@ class ImportTests(unittest.TestCase):
             ):
                 exec(f"from {name} import *", globals)
             self.assertNotIn(b"invalid_type", globals)
-        with _ready_to_import() as (name, path):
+        with ready_to_import() as (name, path):
             with open(path, 'w', encoding='utf-8') as f:
                 f.write("globals()[b'invalid_type'] = object()")
             globals = {}
@@ -818,7 +798,7 @@ class FilePermissionTests(unittest.TestCase):
     )
     def test_creation_mode(self):
         mask = 0o022
-        with temp_umask(mask), _ready_to_import() as (name, path):
+        with temp_umask(mask), ready_to_import() as (name, path):
             cached_path = importlib.util.cache_from_source(path)
             module = __import__(name)
             if not os.path.exists(cached_path):
@@ -837,7 +817,7 @@ class FilePermissionTests(unittest.TestCase):
     def test_cached_mode_issue_2051(self):
         # permissions of .pyc should match those of .py, regardless of mask
         mode = 0o600
-        with temp_umask(0o022), _ready_to_import() as (name, path):
+        with temp_umask(0o022), ready_to_import() as (name, path):
             cached_path = importlib.util.cache_from_source(path)
             os.chmod(path, mode)
             __import__(name)
@@ -853,7 +833,7 @@ class FilePermissionTests(unittest.TestCase):
     @os_helper.skip_unless_working_chmod
     def test_cached_readonly(self):
         mode = 0o400
-        with temp_umask(0o022), _ready_to_import() as (name, path):
+        with temp_umask(0o022), ready_to_import() as (name, path):
             cached_path = importlib.util.cache_from_source(path)
             os.chmod(path, mode)
             __import__(name)
@@ -868,7 +848,7 @@ class FilePermissionTests(unittest.TestCase):
     def test_pyc_always_writable(self):
         # Initially read-only .pyc files on Windows used to cause problems
         # with later updates, see issue #6074 for details
-        with _ready_to_import() as (name, path):
+        with ready_to_import() as (name, path):
             # Write a Python file, make it read-only and import it
             with open(path, 'w', encoding='utf-8') as f:
                 f.write("x = 'original'\n")