Add test for PURE_PYTHON environment.

CHANGES.rst

@@ -5,6 +5,9 @@
 4.0.7 (unreleased)
 ------------------
 
+- Add ``PURE_PYTHON`` environment variable support:  if set, the C
+  extensions will not be built or imported.
+
 
 4.0.6 (2013-01-03)
 ------------------

persistent/__init__.py

@@ -15,20 +15,24 @@
 
 Fall back to pure Python implementations.
 """
-try:
+import os
+
+PURE_PYTHON = os.environ.get('PURE_PYTHON')
+if not PURE_PYTHON:
+    try:
         from persistent.cPersistence import Persistent
         from persistent.cPersistence import GHOST
         from persistent.cPersistence import UPTODATE
         from persistent.cPersistence import CHANGED
         from persistent.cPersistence import STICKY
         from persistent.cPersistence import simple_new
-except ImportError: #pragma NO COVER
+    except ImportError: #pragma NO COVER
         from persistent.persistence import Persistent
         from persistent.persistence import GHOST
         from persistent.persistence import UPTODATE
         from persistent.persistence import CHANGED
         from persistent.persistence import STICKY
-else:
+    else:
         from persistent._compat import copy_reg
         copy_reg.constructor(simple_new)
         # Make an interface declaration for Persistent, if zope.interface
@@ -41,14 +45,25 @@ else:
             from persistent.interfaces import IPersistent
             classImplements(Persistent, IPersistent)
 
-try:
+    try:
         from persistent.cPickleCache import PickleCache
-except ImportError: #pragma NO COVER
+    except ImportError: #pragma NO COVER
         from persistent.picklecache import PickleCache
 
-try:
+    try:
         import persistent.TimeStamp
-except ImportError: #pragma NO COVER
+    except ImportError: #pragma NO COVER
+        import persistent.timestamp as TimeStamp
+        import sys
+        sys.modules['persistent.TimeStamp'
+                   ] = sys.modules['persistent.timestamp']
+else: #pragma NO COVER
+    from persistent.persistence import Persistent
+    from persistent.persistence import GHOST
+    from persistent.persistence import UPTODATE
+    from persistent.persistence import CHANGED
+    from persistent.persistence import STICKY
+    from persistent.picklecache import PickleCache
     import persistent.timestamp as TimeStamp
     import sys
     sys.modules['persistent.TimeStamp'] = sys.modules['persistent.timestamp']

persistent/tests/test_persistence.py

@@ -11,6 +11,7 @@
 # FOR A PARTICULAR PURPOSE.
 #
 ##############################################################################
+import os
 import unittest
 
 class _Persistent_Base(object):
@@ -1321,11 +1322,12 @@ class PyPersistentTests(unittest.TestCase, _Persistent_Base):
  
 _add_to_suite = [PyPersistentTests]
 
-try:
+if not os.environ.get('PURE_PYTHON'):
+    try:
         from persistent import cPersistence
-except ImportError:
+    except ImportError:
         pass
-else:
+    else:
         class CPersistentTests(unittest.TestCase, _Persistent_Base):
 
             def _getTargetClass(self):

setup.py

@@ -31,11 +31,12 @@ README = (open(os.path.join(here, 'README.rst')).read()
 py_impl = getattr(platform, 'python_implementation', lambda: None)
 is_pypy = py_impl() == 'PyPy'
 is_jython = 'java' in sys.platform
+is_pure = os.environ.get('PURE_PYTHON')
 
 # Jython cannot build the C optimizations, while on PyPy they are
 # anti-optimizations (the C extension compatibility layer is known-slow,
 # and defeats JIT opportunities).
-if is_pypy or is_jython:
+if is_pypy or is_jython or is_pure:
     ext_modules = headers = []
 else:
     ext_modules = [Extension(name = 'persistent.cPersistence',

tox.ini

@@ -3,7 +3,7 @@ envlist =
 # Jython support pending 2.7 support, due 2012-07-15 or so.  See:
 # http://fwierzbicki.blogspot.com/2012/03/adconion-to-fund-jython-27.html
 #   py26,py27,py32,jython,pypy,coverage,docs
-    py26,py27,pypy,py32,py33,coverage,docs
+    py26,py27,py27-pure,pypy,py32,py33,coverage,docs
 
 [testenv]
 deps =
@@ -15,6 +15,16 @@ commands =
 commands = 
    jython setup.py test -q
 
+[testenv:py27-pure]
+basepython =
+    python2.7
+setenv =
+    PURE_PYTHON = 1
+deps =
+    zope.interface
+commands = 
+    python setup.py test -q
+
 [testenv:coverage]
 basepython =
     python2.6