gh-127873: Only check sys.flags.ignore_environment for PYTHON* env vars (#127877)

Author: hugovk

.github/CODEOWNERS

@@ -304,3 +304,7 @@ Lib/test/test_configparser.py @jaraco
 Doc/reference/                @willingc @AA-Turner
 
 **/*weakref*                  @kumaraditya303
+
+# Colorize
+Lib/_colorize.py              @hugovk
+Lib/test/test__colorize.py    @hugovk

Lib/_colorize.py

@@ -42,15 +42,14 @@ def can_colorize(*, file=None) -> bool:
             return False
         if os.environ.get("PYTHON_COLORS") == "1":
             return True
-        if "NO_COLOR" in os.environ:
-            return False
+    if "NO_COLOR" in os.environ:
+        return False
     if not COLORIZE:
         return False
-    if not sys.flags.ignore_environment:
-        if "FORCE_COLOR" in os.environ:
-            return True
-        if os.environ.get("TERM") == "dumb":
-            return False
+    if "FORCE_COLOR" in os.environ:
+        return True
+    if os.environ.get("TERM") == "dumb":
+        return False
 
     if not hasattr(file, "fileno"):
         return False

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_capi/test_misc.py

@@ -75,8 +75,11 @@ class InstanceMethod:
     id = _testcapi.instancemethod(id)
     testfunction = _testcapi.instancemethod(testfunction)
 
+
 CURRENT_THREAD_REGEX = r'Current thread.*:\n' if not support.Py_GIL_DISABLED else r'Stack .*:\n'
 
+
+@support.force_not_colorized_test_class
 class CAPITest(unittest.TestCase):
 
     def test_instancemethod(self):

Lib/test/test_cmd_line_script.py

@@ -88,6 +88,8 @@ def _make_test_zip_pkg(zip_dir, zip_basename, pkg_name, script_basename,
     importlib.invalidate_caches()
     return to_return
 
+
+@support.force_not_colorized_test_class
 class CmdLineTest(unittest.TestCase):
     def _check_output(self, script_name, exit_code, data,
                              expected_file, expected_argv0,

Lib/test/test_compileall.py

@@ -766,6 +766,7 @@ def test_d_compile_error(self):
         rc, out, err = self.assertRunNotOK('-q', '-d', 'dinsdale', self.pkgdir)
         self.assertRegex(out, b'File "dinsdale')
 
+    @support.force_not_colorized
     def test_d_runtime_error(self):
         bazfn = script_helper.make_script(self.pkgdir, 'baz', 'raise Exception')
         self.assertRunOK('-q', '-d', 'dinsdale', self.pkgdir)

Lib/test/test_eof.py

@@ -2,7 +2,7 @@
 
 import sys
 from codecs import BOM_UTF8
-from test import support
+from test.support import force_not_colorized
 from test.support import os_helper
 from test.support import script_helper
 from test.support import warnings_helper
@@ -44,6 +44,7 @@ def test_EOFS(self):
         self.assertEqual(cm.exception.text, "ä = '''thîs is ")
         self.assertEqual(cm.exception.offset, 5)
 
+    @force_not_colorized
     def test_EOFS_with_file(self):
         expect = ("(<string>, line 1)")
         with os_helper.temp_dir() as temp_dir:
@@ -123,6 +124,7 @@ def test_line_continuation_EOF(self):
         self.assertEqual(str(cm.exception), expect)
 
     @unittest.skipIf(not sys.executable, "sys.executable required")
+    @force_not_colorized
     def test_line_continuation_EOF_from_file_bpo2180(self):
         """Ensure tok_nextc() does not add too many ending newlines."""
         with os_helper.temp_dir() as temp_dir:

Lib/test/test_exceptions.py

@@ -1465,6 +1465,7 @@ def gen():
 
     @cpython_only
     @unittest.skipIf(_testcapi is None, "requires _testcapi")
+    @force_not_colorized
     def test_recursion_normalizing_infinite_exception(self):
         # Issue #30697. Test that a RecursionError is raised when
         # maximum recursion depth has been exceeded when creating
@@ -2180,6 +2181,7 @@ def test_multiline_not_highlighted(self):
                 self.assertEqual(result[-len(expected):], expected)
 
 
+@support.force_not_colorized_test_class
 class SyntaxErrorTests(unittest.TestCase):
     maxDiff = None
 

Lib/test/test_import/__init__.py

@@ -29,9 +29,21 @@
 
 from test.support import os_helper
 from test.support import (
-    STDLIB_DIR, swap_attr, swap_item, cpython_only, is_apple_mobile, is_emscripten,
-    is_wasi, run_in_subinterp, run_in_subinterp_with_config, Py_TRACE_REFS,
-    requires_gil_enabled, Py_GIL_DISABLED, no_rerun)
+    STDLIB_DIR,
+    swap_attr,
+    swap_item,
+    cpython_only,
+    is_apple_mobile,
+    is_emscripten,
+    is_wasi,
+    run_in_subinterp,
+    run_in_subinterp_with_config,
+    Py_TRACE_REFS,
+    requires_gil_enabled,
+    Py_GIL_DISABLED,
+    no_rerun,
+    force_not_colorized_test_class,
+)
 from test.support.import_helper import (
     forget, make_legacy_pyc, unlink, unload, ready_to_import,
     DirsOnSysPath, CleanImport, import_module)
@@ -333,6 +345,7 @@ def _from_subinterp(cls, name, interpid, pipe, script_kwargs):
         return cls.parse(text.decode())
 
 
+@force_not_colorized_test_class
 class ImportTests(unittest.TestCase):
 
     def setUp(self):