Freezer bugfix: replace datetime instances when leaving freeze context

manager.

The labix mocker does not replace classes of instances.
Since we patch the datetime class in the freezer, we need to replace all
instances of patched datetime classes when leaving the freeze context manager.

docs/HISTORY.txt

@@ -5,7 +5,8 @@ Changelog
 1.10.3 (unreleased)
 -------------------
 
-- Nothing changed yet.
+- Freezer bugfix: replace datetime instances when leaving freeze context manager.
+  [jone]
 
 
 1.10.2 (2015-07-30)

ftw/testing/freezer.py

@@ -2,9 +2,11 @@
 from datetime import datetime
 from datetime import timedelta
 from mocker import expect
+from mocker import global_replace
 from mocker import Mocker
 from mocker import ProxyReplacer
 import calendar
+import gc
 
 
 class FreezedClock(object):
@@ -66,9 +68,26 @@ def now(tz=None):
         return self
 
     def __exit__(self, exc_type, exc_value, traceback):
+        datetime_mock_class = datetime
         self.mocker.restore()
         self.mocker.verify()
 
+        # The labix mocker does only replace pointers to the mock-class which
+        # are in dicts.
+        # This does not change the class of instances of our mock-class.
+        # In order to be able to commit while the time is freezed,
+        # we need to replace those classes manually.
+        # Since we cannot patch the class of existing instances,
+        # we need to construct new instances with the real datetime class and
+        # replace all mock instances.
+        for referrer in gc.get_referrers(datetime_mock_class):
+            if not isinstance(referrer, datetime_mock_class):
+                continue
+            if getattr(referrer, '__class__') != datetime_mock_class:
+                continue
+            replacement = datetime(*referrer.timetuple()[:6] + (referrer.microsecond,))
+            global_replace(referrer, replacement)
+
 
 @contextmanager
 def freeze(new_now=None):

ftw/testing/tests/test_freezer.py

@@ -1,9 +1,11 @@
 from DateTime import DateTime
 from ftw.testing import freeze
+from plone.mocktestcase.dummy import Dummy
 from unittest2 import TestCase
 import datetime
 import pytz
 import time
+import transaction
 
 datetime_module = datetime
 datetime_class = datetime.datetime
@@ -134,3 +136,17 @@ def test_freeze_relative_to_current_time(self):
             clock.forward(hours=1)
             after = datetime.datetime.now()
             self.assertEquals(60 * 60, (after - before).seconds)
+
+    def test_patches_are_removed_from_freezed_instances(self):
+        with freeze():
+            dummy = Dummy(datetime_class=datetime.datetime,
+                          date=datetime.datetime.now())
+
+        self.assertEquals(
+            {'class': 'datetime.datetime',
+             'instance': 'datetime.datetime'},
+
+            {'class': '.'.join((dummy.datetime_class.__module__,
+                                dummy.datetime_class.__name__)),
+             'instance': '.'.join((type(dummy.date).__module__,
+                                   type(dummy.date).__name__))})