Respect PURE_PYTHON environment variable set to 0 (#158)

Setting to 0 should be equivalent to not setting the variable.

Refs zopefoundation/meta#283

Author: perrinjerome

CHANGES.rst

@@ -6,6 +6,8 @@ For changes before version 3.0, see ``HISTORY.rst``.
 7.1 (unreleased)
 ----------------
 
+- Respect ``PURE_PYTHON`` environment variable set to ``0`` when running tests.
+
 
 7.0 (2024-05-30)
 ----------------

src/AccessControl/tests/testSecurityManager.py

@@ -14,9 +14,10 @@
 """Tests for the SecurityManager implementations
 """
 
-import os
 import unittest
 
+from ..Implementation import PURE_PYTHON
+
 
 _THREAD_ID = 123
 
@@ -251,7 +252,7 @@ def _getTargetClass(self):
         return SecurityManager
 
 
-@unittest.skipIf(os.environ.get('PURE_PYTHON'), reason="Test expects C impl.")
+@unittest.skipIf(PURE_PYTHON, reason="Test expects C impl.")
 class C_SecurityManagerTests(SecurityManagerTestBase,
                              ISecurityManagerConformance,
                              unittest.TestCase):

src/AccessControl/tests/testZopeSecurityPolicy.py

@@ -12,7 +12,6 @@
 ##############################################################################
 
 import _thread as thread
-import os
 import sys
 import unittest
 from doctest import DocTestSuite
@@ -27,6 +26,8 @@
 from AccessControl.SecurityManagement import SecurityContext
 from AccessControl.userfolder import UserFolder
 
+from ..Implementation import PURE_PYTHON
+
 
 user_roles = ('RoleOfUser',)
 eo_roles = ('RoleOfExecutableOwner',)
@@ -772,7 +773,7 @@ def test_suite():
         unittest.defaultTestLoader.loadTestsFromTestCase(Python_ZSPTests))
     suite.addTest(
         unittest.defaultTestLoader.loadTestsFromTestCase(Python_SMTests))
-    if not os.environ.get('PURE_PYTHON'):
+    if not PURE_PYTHON:
         suite.addTest(
             unittest.defaultTestLoader.loadTestsFromTestCase(C_ZSPTests))
         suite.addTest(