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bpo-12383: Refactor subprocess test_empty_env (#1874)

Bugfix: This test wasn't being run because it was skipping based on the
presence of Py_ENABLE_SHARED rather than its value.  It is always present
on POSIX systems but defaults to 0.

Refactoring: Move the environment variables that can be ignored into a
function.  Parse the list from the child process and filter out the ones
to exclude in the parent before checking that the rest is empty.

Feature: Adds always present environment variables to ignore when
running in a Gentoo sandbox so that the test can pass there.
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gpshead committed May 30, 2017
1 parent 9c972b5 commit b351248c1fa74277b886b0c9a2e1c2f65fabe9ef
Showing with 20 additions and 12 deletions.
  1. +20 −12 Lib/test/test_subprocess.py
@@ -630,21 +630,29 @@ def test_env(self):
# Python
@unittest.skipIf(sys.platform == 'win32',
'cannot test an empty env on Windows')
@unittest.skipIf(sysconfig.get_config_var('Py_ENABLE_SHARED') is not None,
'the python library cannot be loaded '
'with an empty environment')
@unittest.skipIf(sysconfig.get_config_var('Py_ENABLE_SHARED') == 1,
'The Python shared library cannot be loaded '
'with an empty environment.')
def test_empty_env(self):
"""Verify that env={} is as empty as possible."""
def is_env_var_to_ignore(var_name):
"""Determine if an environment variable is under our control."""
# This excludes some __CF_* and VERSIONER_* keys MacOS insists
# on adding even when the environment in exec is empty.
# Gentoo sandboxes also force LD_PRELOAD and SANDBOX_* to exist.
return ('VERSIONER' in k or '__CF' in k or # MacOS
k == 'LD_PRELOAD' or k.startswith('SANDBOX')) # Gentoo
with subprocess.Popen([sys.executable, "-c",
'import os; '
'print(list(os.environ.keys()))'],
stdout=subprocess.PIPE,
env={}) as p:
'import os; print(list(os.environ.keys()))'],
stdout=subprocess.PIPE, env={}) as p:
stdout, stderr = p.communicate()
self.assertIn(stdout.strip(),
(b"[]",
# Mac OS X adds __CF_USER_TEXT_ENCODING variable to an empty
# environment
b"['__CF_USER_TEXT_ENCODING']"))
child_env_names = eval(stdout.strip())
self.assertIsInstance(child_env_names, list)
child_env_names = [k for k in child_env_names
if not is_env_var_to_ignore(k)]
self.assertEqual(child_env_names, [])
def test_communicate_stdin(self):
p = subprocess.Popen([sys.executable, "-c",

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gpshead May 30, 2017

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Obvious typo fixed by 85aba23

I'm not sure how I managed to have passing tests locally with that in place.

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gpshead commented on b351248 May 30, 2017

Obvious typo fixed by 85aba23

I'm not sure how I managed to have passing tests locally with that in place.

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