Issue python#126: fix undefined behaviour of C-Python tests

Load the module "stackless" early in all C-Python tests. This ensures a defined
behaviour of the tests even, if the execution order gets randomised.

https://bitbucket.org/stackless-dev/stackless/issues/126

Author: Anselm Kruis

Lib/test/pickletester.py

@@ -9,7 +9,7 @@
 
 from test.support import (
     TestFailed, TESTFN, run_with_locale, no_tracing,
-    _2G, _4G, bigmemtest,
+    _2G, _4G, bigmemtest, stackless,
     )
 
 from pickle import bytes_types
@@ -393,12 +393,11 @@ def create_dynamic_class(name, bases):
 
 # xrange(5) pickled from 2.x with protocol 2
 DATA4 = b'\x80\x02c__builtin__\nxrange\nq\x00K\x00K\x05K\x01\x87q\x01Rq\x02.'
-try:
-    import stackless
+if stackless:
     DATA4_SLP = b'\x80\x02cstackless._wrap\nrange\nq\x00K\x00K\x05K\x01\x87q\x01Rq\x02)b.'
-except:
+else:
     DATA4_SLP = DATA4
-    
+
 
 # a SimpleCookie() object pickled from 2.x with protocol 2
 DATA5 = (b'\x80\x02cCookie\nSimpleCookie\nq\x00)\x81q\x01U\x03key'
@@ -1222,9 +1221,7 @@ def test_unpickle_from_2x(self):
         loaded = self.loads(DATA3)
         self.assertEqual(loaded, set([1, 2]))
         loaded = self.loads(DATA4_SLP)
-        try:
-            import stackless
-        except ImportError:
+        if not stackless:
             self.assertEqual(type(loaded), type(range(0)))
         else:
             pass # stackless provides a fake range for unpickling

Lib/test/support/__init__.py

@@ -26,6 +26,11 @@
 import struct
 import tempfile
 
+try:
+    import stackless
+except ImportError:
+    stackless = None
+
 try:
     import _thread, threading
 except ImportError:

Lib/test/test_multiprocessing.py

@@ -21,12 +21,6 @@
 import test.support
 import test.script_helper
 
-try:
-    import stackless
-    usingStackless = True
-except ImportError:
-    usingStackless = False
-
 
 # Skip tests if _multiprocessing wasn't built.
 _multiprocessing = test.support.import_module('_multiprocessing')
@@ -1812,8 +1806,8 @@ def errback(exc):
         p.close()
         p.join()
 
-    @unittest.skipIf(usingStackless, "Stackless can pickle lambdas")
-    def test_unpickleable_result(self):    
+    @unittest.skipIf(test.support.stackless, "Stackless can pickle lambdas")
+    def test_unpickleable_result(self):
         from multiprocessing.pool import MaybeEncodingError
         p = multiprocessing.Pool(2)
 

Lib/test/test_pep352.py

@@ -1,7 +1,7 @@
 import unittest
 import builtins
 import warnings
-from test.support import run_unittest
+from test.support import run_unittest, stackless
 import os
 from platform import system as platform_system
 
@@ -32,11 +32,6 @@ def test_inheritance(self):
 
         inheritance_tree = open(os.path.join(os.path.split(__file__)[0],
                                                 'exception_hierarchy.txt'))
-        try:
-            import stackless
-            haveStackless = True
-        except:
-            haveStackless = False
         try:
             superclass_name = inheritance_tree.readline().rstrip()
             try:
@@ -62,7 +57,7 @@ def test_inheritance(self):
                 if '[' in exc_name:
                     left_bracket = exc_name.index('[')
                     exc_name = exc_name[:left_bracket-1]  # cover space
-                if not haveStackless and exc_name == "TaskletExit":
+                if stackless is None and exc_name == "TaskletExit":
                     exc_set.discard(exc_name)
                     continue
                 try:

Lib/test/test_sys.py

@@ -665,11 +665,7 @@ def inner():
         import collections
         check(collections.defaultdict.default_factory, size('3PP'))
         # wrapper_descriptor (descriptor object)
-        try:
-            import stackless
-            slxtra = 'i'
-        except:
-            slxtra = ''
+        slxtra = 'i' if test.support.stackless else ''
         check(int.__add__, size('3P2P' + slxtra))
         # method-wrapper (descriptor object)
         check({}.__iter__, size('2P'))
@@ -718,11 +714,7 @@ class C(object): pass
         nfrees = len(x.f_code.co_freevars)
         extras = x.f_code.co_stacksize + x.f_code.co_nlocals +\
                   ncells + nfrees - 1
-        try:
-            import stackless
-            slextra = 'P'
-        except:
-            slextra = ''
+        slextra = 'P' if test.support.stackless else ''
         check(x, vsize('12P3i' + CO_MAXBLOCKS*'3i' + slextra + 'P' + extras*'P'))
         # function
         def func(): pass

Stackless/changelog.txt

@@ -9,6 +9,10 @@ What's New in Stackless 3.X.X?
 
 *Release date: 20XX-XX-XX*
 
+- https://bitbucket.org/stackless-dev/stackless/issues/126
+  Load the module stackless early in all C-Python tests. This ensures a defined
+  behaviour of the tests even, if the execution order gets randomised.
+
 - https://bitbucket.org/stackless-dev/stackless/issues/125
   This document (changelog.txt) is included in the documentation as
   "What’s New in Stackless-Python ..."