python · JelleZijlstra · May 5, 2025 · Apr 27, 2025 · Apr 28, 2025 · May 4, 2025
@@ -26,6 +26,7 @@
 from test.support import os_helper
 from test.support import skip_emscripten_stack_overflow, skip_wasi_stack_overflow
 from test.support.ast_helper import ASTTestMixin
+from test.support.import_helper import ensure_lazy_imports
 from test.test_ast.utils import to_tuple
 from test.test_ast.snippets import (
     eval_tests, eval_results, exec_tests, exec_results, single_tests, single_results
@@ -47,6 +48,12 @@ def ast_repr_update_snapshots() -> None:
     AST_REPR_DATA_FILE.write_text("\n".join(data))
 
 
+class LazyImportTest(unittest.TestCase):
+    @support.cpython_only
+    def test_lazy_import(self):
+        ensure_lazy_imports("ast", {"contextlib", "enum", "inspect", "re", "collections", "argparse"})
+
+
 class AST_Tests(unittest.TestCase):
     maxDiff = None
 

diff --git a/Lib/test/test_base64.py b/Lib/test/test_base64.py
@@ -3,8 +3,16 @@
 import binascii
 import os
 from array import array
+from test.support import cpython_only
 from test.support import os_helper
 from test.support import script_helper
+from test.support.import_helper import ensure_lazy_imports
+
+
+class LazyImportTest(unittest.TestCase):
+    @cpython_only
+    def test_lazy_import(self):
+        ensure_lazy_imports("base64", {"re", "getopt"})
 
 
 class LegacyBase64TestCase(unittest.TestCase):

diff --git a/Lib/test/test_cmd.py b/Lib/test/test_cmd.py
@@ -11,9 +11,15 @@
 import io
 import textwrap
 from test import support
-from test.support.import_helper import import_module
+from test.support.import_helper import ensure_lazy_imports, import_module
 from test.support.pty_helper import run_pty
 
+class LazyImportTest(unittest.TestCase):
+    @support.cpython_only
+    def test_lazy_import(self):
+        ensure_lazy_imports("cmd", {"inspect", "string"})
+
+
 class samplecmdclass(cmd.Cmd):
     """
     Instance the sampleclass:

diff --git a/Lib/test/test_csv.py b/Lib/test/test_csv.py
@@ -10,7 +10,8 @@
 import gc
 import pickle
 from test import support
-from test.support import import_helper, check_disallow_instantiation
+from test.support import cpython_only, import_helper, check_disallow_instantiation
+from test.support.import_helper import ensure_lazy_imports
 from itertools import permutations
 from textwrap import dedent
 from collections import OrderedDict
@@ -1565,6 +1566,10 @@ class MiscTestCase(unittest.TestCase):
     def test__all__(self):
         support.check__all__(self, csv, ('csv', '_csv'))
 
+    @cpython_only
+    def test_lazy_import(self):
+        ensure_lazy_imports("csv", {"re"})
+
     def test_subclassable(self):
         # issue 44089
         class Foo(csv.Error): ...

@@ -4,6 +4,16 @@
 import time
 import unittest
 
+from test.support import cpython_only
+from test.support.import_helper import ensure_lazy_imports
+
+
+class TestImportTime(unittest.TestCase):
+
+    @cpython_only
+    def test_lazy_import(self):
+        ensure_lazy_imports("email.utils", {"random", "socket"})
+
 
 class DateTimeTests(unittest.TestCase):
 

@@ -19,7 +19,8 @@
 from pickle import dumps, loads, PicklingError, HIGHEST_PROTOCOL
 from test import support
 from test.support import ALWAYS_EQ, REPO_ROOT
-from test.support import threading_helper
+from test.support import threading_helper, cpython_only
+from test.support.import_helper import ensure_lazy_imports
 from datetime import timedelta
 
 python_version = sys.version_info[:2]
@@ -5288,6 +5289,10 @@ class MiscTestCase(unittest.TestCase):
     def test__all__(self):
         support.check__all__(self, enum, not_exported={'bin', 'show_flag_values'})
 
+    @cpython_only
+    def test_lazy_import(self):
+        ensure_lazy_imports("enum", {"functools", "warnings", "inspect", "re"})
+
     def test_doc_1(self):
         class Single(Enum):
             ONE = 1

@@ -23,6 +23,7 @@
 
 from test.support import import_helper
 from test.support import threading_helper
+from test.support import cpython_only
 from test.support import EqualToForwardRef
 
 import functools
@@ -63,6 +64,14 @@ def __add__(self, other):
 class MyDict(dict):
     pass
 
+class TestImportTime(unittest.TestCase):
+
+    @cpython_only
+    def test_lazy_import(self):
+        import_helper.ensure_lazy_imports(
+            "functools", {"os", "weakref", "typing", "annotationlib", "warnings"}
+        )
+
 
 class TestPartial:
 

@@ -6,7 +6,8 @@
 from functools import partial
 
 from test import support
-from test.support import os_helper
+from test.support import cpython_only, os_helper
+from test.support.import_helper import ensure_lazy_imports
 
 
 # TODO:
@@ -931,6 +932,10 @@ def test__all__(self):
         support.check__all__(self, gettext,
                              not_exported={'c2py', 'ENOENT'})
 
+    @cpython_only
+    def test_lazy_import(self):
+        ensure_lazy_imports("gettext", {"re", "warnings", "locale"})
+
 
 if __name__ == '__main__':
     unittest.main()

diff --git a/Lib/test/test_locale.py b/Lib/test/test_locale.py
@@ -1,13 +1,18 @@
 from decimal import Decimal
-from test.support import verbose, is_android, linked_to_musl, os_helper
+from test.support import cpython_only, verbose, is_android, linked_to_musl, os_helper
 from test.support.warnings_helper import check_warnings
-from test.support.import_helper import import_fresh_module
+from test.support.import_helper import ensure_lazy_imports, import_fresh_module
 from unittest import mock
 import unittest
 import locale
 import sys
 import codecs
 
+class LazyImportTest(unittest.TestCase):
+    @cpython_only
+    def test_lazy_import(self):
+        ensure_lazy_imports("locale", {"re", "warnings"})
+
 
 class BaseLocalizedTest(unittest.TestCase):
     #

@@ -6,7 +6,8 @@
 import unittest.mock
 from platform import win32_edition
 from test import support
-from test.support import force_not_colorized, os_helper
+from test.support import cpython_only, force_not_colorized, os_helper
+from test.support.import_helper import ensure_lazy_imports
 
 try:
     import _winapi
@@ -435,6 +436,10 @@ class MiscTestCase(unittest.TestCase):
     def test__all__(self):
         support.check__all__(self, mimetypes)
 
+    @cpython_only
+    def test_lazy_import(self):
+        ensure_lazy_imports("mimetypes", {"os", "posixpath", "urllib.parse", "argparse"})
+
 
 class CommandLineTest(unittest.TestCase):
     @force_not_colorized

diff --git a/Lib/test/test_optparse.py b/Lib/test/test_optparse.py
@@ -14,8 +14,9 @@
 
 from io import StringIO
 from test import support
-from test.support import os_helper
+from test.support import cpython_only, os_helper
 from test.support.i18n_helper import TestTranslationsBase, update_translation_snapshots
+from test.support.import_helper import ensure_lazy_imports
 
 import optparse
 from optparse import make_option, Option, \
@@ -1655,6 +1656,10 @@ def test__all__(self):
         not_exported = {'check_builtin', 'AmbiguousOptionError', 'NO_DEFAULT'}
         support.check__all__(self, optparse, not_exported=not_exported)
 
+    @cpython_only
+    def test_lazy_import(self):
+        ensure_lazy_imports("optparse", {"textwrap"})
+
 
 class TestTranslations(TestTranslationsBase):
     def test_translations(self):

@@ -16,6 +16,7 @@
 from urllib.request import pathname2url
 
 from test.support import import_helper
+from test.support import cpython_only
 from test.support import is_emscripten, is_wasi
 from test.support import infinite_recursion
 from test.support import os_helper
@@ -80,6 +81,12 @@ def test_is_notimplemented(self):
         self.assertTrue(isinstance(pathlib.UnsupportedOperation(), NotImplementedError))
 
 
+class LazyImportTest(unittest.TestCase):
+    @cpython_only
+    def test_lazy_import(self):
+        import_helper.ensure_lazy_imports("pathlib", {"shutil"})
+
+
 #
 # Tests for the pure classes.
 #

diff --git a/Lib/test/test_pickle.py b/Lib/test/test_pickle.py
@@ -15,7 +15,8 @@
 import doctest
 import unittest
 from test import support
-from test.support import import_helper, os_helper
+from test.support import cpython_only, import_helper, os_helper
+from test.support.import_helper import ensure_lazy_imports
 
 from test.pickletester import AbstractHookTests
 from test.pickletester import AbstractUnpickleTests
@@ -36,6 +37,12 @@
     has_c_implementation = False
 
 
+class LazyImportTest(unittest.TestCase):
+    @cpython_only
+    def test_lazy_import(self):
+        ensure_lazy_imports("pickle", {"re"})
+
+
 class PyPickleTests(AbstractPickleModuleTests, unittest.TestCase):
     dump = staticmethod(pickle._dump)
     dumps = staticmethod(pickle._dumps)

diff --git a/Lib/test/test_pprint.py b/Lib/test/test_pprint.py
@@ -11,6 +11,9 @@
 import types
 import unittest
 
+from test.support import cpython_only
+from test.support.import_helper import ensure_lazy_imports
+
 # list, tuple and dict subclasses that do or don't overwrite __repr__
 class list2(list):
     pass
@@ -129,6 +132,10 @@ def setUp(self):
         self.b = list(range(200))
         self.a[-12] = self.b
 
+    @cpython_only
+    def test_lazy_import(self):
+        ensure_lazy_imports("pprint", {"dataclasses", "re"})
+
     def test_init(self):
         pp = pprint.PrettyPrinter()
         pp = pprint.PrettyPrinter(indent=4, width=40, depth=5,

diff --git a/Lib/test/test_pstats.py b/Lib/test/test_pstats.py
@@ -1,6 +1,7 @@
 import unittest
 
 from test import support
+from test.support.import_helper import ensure_lazy_imports
 from io import StringIO
 from pstats import SortKey
 from enum import StrEnum, _test_simple_enum
@@ -10,6 +11,12 @@
 import tempfile
 import cProfile
 
+class LazyImportTest(unittest.TestCase):
+    @support.cpython_only
+    def test_lazy_import(self):
+        ensure_lazy_imports("pstats", {"typing"})
+
+
 class AddCallersTestCase(unittest.TestCase):
     """Tests for pstats.add_callers helper."""
 

diff --git a/Lib/test/test_shlex.py b/Lib/test/test_shlex.py
@@ -3,6 +3,7 @@
 import shlex
 import string
 import unittest
+from test.support import cpython_only
 from test.support import import_helper
 
 
@@ -364,6 +365,7 @@ def testPunctuationCharsReadOnly(self):
         with self.assertRaises(AttributeError):
             shlex_instance.punctuation_chars = False
 
+    @cpython_only
     def test_lazy_imports(self):
         import_helper.ensure_lazy_imports('shlex', {'collections', 're', 'os'})
 

diff --git a/Lib/test/test_socket.py b/Lib/test/test_socket.py
@@ -2,8 +2,9 @@
 from unittest import mock
 from test import support
 from test.support import (
-    is_apple, os_helper, refleak_helper, socket_helper, threading_helper
+    cpython_only, is_apple, os_helper, refleak_helper, socket_helper, threading_helper
 )
+from test.support.import_helper import ensure_lazy_imports
 import _thread as thread
 import array
 import contextlib
@@ -257,6 +258,12 @@ def downgrade_malformed_data_warning():
 # Size in bytes of the int type
 SIZEOF_INT = array.array("i").itemsize
 
+class TestLazyImport(unittest.TestCase):
+    @cpython_only
+    def test_lazy_import(self):
+        ensure_lazy_imports("socket", {"array", "selectors"})
+
+
 class SocketTCPTest(unittest.TestCase):
 
     def setUp(self):

diff --git a/Lib/test/test_string/test_string.py b/Lib/test/test_string/test_string.py
@@ -2,6 +2,14 @@
 import string
 from string import Template
 import types
+from test.support import cpython_only
+from test.support.import_helper import ensure_lazy_imports
+
+
+class LazyImportTest(unittest.TestCase):
+    @cpython_only
+    def test_lazy_import(self):
+        ensure_lazy_imports("base64", {"re", "collections"})
 
 
 class ModuleTest(unittest.TestCase):

diff --git a/Lib/test/test_threading.py b/Lib/test/test_threading.py
@@ -5,7 +5,7 @@
 import test.support
 from test.support import threading_helper, requires_subprocess, requires_gil_enabled
 from test.support import verbose, cpython_only, os_helper
-from test.support.import_helper import import_module
+from test.support.import_helper import ensure_lazy_imports, import_module
 from test.support.script_helper import assert_python_ok, assert_python_failure
 from test.support import force_not_colorized
 
@@ -120,6 +120,10 @@ def tearDown(self):
 class ThreadTests(BaseTestCase):
     maxDiff = 9999
 
+    @cpython_only
+    def test_lazy_import(self):
+        ensure_lazy_imports("threading", {"functools", "warnings"})
+
     @cpython_only
     def test_name(self):
         def func(): pass