Remove PYTHON* env vars to isolate colour tests

Lib/test/support/__init__.py

@@ -61,6 +61,7 @@
     "without_optimizer",
     "force_not_colorized",
     "force_not_colorized_test_class",
+    "make_clean_env",
     "BrokenIter",
     "in_systemd_nspawn_sync_suppressed",
     "run_no_yield_async_fn", "run_yielding_async_fn", "async_yield",
@@ -2871,6 +2872,16 @@ def new_setUpClass(cls):
     return cls
 
 
+def make_clean_env() -> dict[str, str]:
+    clean_env = os.environ.copy()
+    for k in clean_env.copy():
+        if k.startswith("PYTHON"):
+            clean_env.pop(k)
+    clean_env.pop("FORCE_COLOR", None)
+    clean_env.pop("NO_COLOR", None)
+    return clean_env
+
+
 def initialized_with_pyrepl():
     """Detect whether PyREPL was used during Python initialization."""
     # If the main module has a __file__ attribute it's a Python module, which means PyREPL.

Lib/test/test__colorize.py

@@ -3,7 +3,7 @@
 import unittest
 import unittest.mock
 import _colorize
-from test.support import force_not_colorized
+from test.support import force_not_colorized, make_clean_env
 
 ORIGINAL_CAN_COLORIZE = _colorize.can_colorize
 
@@ -17,6 +17,14 @@ def tearDownModule():
 
 
 class TestColorizeFunction(unittest.TestCase):
+    def setUp(self):
+        # Remove PYTHON* environment variables to isolate from local user
+        # settings and simulate running with `-E`. Such variables should be
+        # added to test methods later to patched os.environ.
+        patcher = unittest.mock.patch("os.environ", new=make_clean_env())
+        self.addCleanup(patcher.stop)
+        patcher.start()
+
     @force_not_colorized
     def test_colorized_detection_checks_for_environment_variables(self):
         flags = unittest.mock.MagicMock(ignore_environment=False)

Lib/test/test_pyrepl/support.py

@@ -101,16 +101,6 @@ def handle_all_events(
 )
 
 
-def make_clean_env() -> dict[str, str]:
-    clean_env = os.environ.copy()
-    for k in clean_env.copy():
-        if k.startswith("PYTHON"):
-            clean_env.pop(k)
-    clean_env.pop("FORCE_COLOR", None)
-    clean_env.pop("NO_COLOR", None)
-    return clean_env
-
-
 class FakeConsole(Console):
     def __init__(self, events, encoding="utf-8") -> None:
         self.events = iter(events)

Lib/test/test_pyrepl/test_pyrepl.py

@@ -10,7 +10,7 @@
 import tempfile
 from unittest import TestCase, skipUnless, skipIf
 from unittest.mock import patch
-from test.support import force_not_colorized
+from test.support import force_not_colorized, make_clean_env
 from test.support import SHORT_TIMEOUT
 from test.support.import_helper import import_module
 from test.support.os_helper import unlink
@@ -23,7 +23,6 @@
     multiline_input,
     code_to_events,
     clean_screen,
-    make_clean_env,
 )
 from _pyrepl.console import Event
 from _pyrepl.readline import (ReadlineAlikeReader, ReadlineConfig,