python · JelleZijlstra · May 5, 2025 · Apr 27, 2025 · Apr 28, 2025 · May 4, 2025
@@ -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]
@@ -1274,6 +1275,10 @@ class Holiday(date, Enum):
            IDES_OF_MARCH = 2013, 3, 15
        self.Holiday = Holiday

+    @cpython_only
+    def test_lazy_import(self):
+        ensure_lazy_imports("enum", {"functools", "warnings", "inspect", "re"})
+
    def test_bool(self):
        # plain Enum members are always True
        class Logic(Enum):

@@ -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:


@@ -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
@@ -129,6 +130,10 @@ class StrSubclass(str):
        for part in p.parts:
            self.assertIs(type(part), str)

+    @cpython_only
+    def test_lazy_import(self):
+        import_helper.ensure_lazy_imports("pathlib", {"shutil"})
+
    def test_str_subclass_common(self):
        self._check_str_subclass('')
        self._check_str_subclass('.')

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