[1.2.X] Fixed #14508 - test suite silences warnings.

Utility functions get_warnings_state and save_warnings_state have been added
to django.test.utils, and methods to django.test.TestCase for convenience.

The implementation is based on the catch_warnings context manager from
Python 2.6.

Backport of [14526] from trunk.

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.2.X@14527 bcc190cf-cafb-0310-a4f2-bffc1f526a37

4 files changed, 48 insertions, 13 deletions

diff --git a/django/test/testcases.py b/django/test/testcases.py
index 276d1f3c41..fc49d0d79b 100644
--- a/django/test/testcases.py
+++ b/django/test/testcases.py
@@ -11,6 +11,7 @@ from django.db import transaction, connections, DEFAULT_DB_ALIAS
 from django.http import QueryDict
 from django.test import _doctest as doctest
 from django.test.client import Client
+from django.test.utils import get_warnings_state, restore_warnings_state
 from django.utils import simplejson
 from django.utils.encoding import smart_str
 
@@ -286,6 +287,19 @@ class TransactionTestCase(unittest.TestCase):
             settings.ROOT_URLCONF = self._old_root_urlconf
             clear_url_caches()
 
+    def save_warnings_state(self):
+        """
+        Saves the state of the warnings module
+        """
+        self._warnings_state = get_warnings_state()
+
+    def restore_warnings_state(self):
+        """
+        Restores the sate of the warnings module to the state
+        saved by save_warnings_state()
+        """
+        restore_warnings_state(self._warnings_state)
+
     def assertRedirects(self, response, expected_url, status_code=302,
                         target_status_code=200, host=None, msg_prefix=''):
         """Asserts that a response redirected to a specific URL, and that the
diff --git a/django/test/utils.py b/django/test/utils.py
index 8ecb5a0e60..517d06ff0b 100644
--- a/django/test/utils.py
+++ b/django/test/utils.py
@@ -1,6 +1,7 @@
 import sys
 import time
 import os
+import warnings
 from django.conf import settings
 from django.core import mail
 from django.core.mail.backends import locmem
@@ -43,6 +44,7 @@ class ContextList(list):
             return False
         return True
 
+
 def instrumented_test_render(self, context):
     """
     An instrumented Template render method, providing a signal
@@ -72,6 +74,7 @@ def setup_test_environment():
 
     deactivate()
 
+
 def teardown_test_environment():
     """Perform any global post-test teardown. This involves:
 
@@ -90,6 +93,25 @@ def teardown_test_environment():
 
     del mail.outbox
 
+
+def get_warnings_state():
+    """
+    Returns an object containing the state of the warnings module
+    """
+    # There is no public interface for doing this, but this implementation of
+    # get_warnings_state and restore_warnings_state appears to work on Python
+    # 2.4 to 2.7.
+    return warnings.filters[:]
+
+
+def restore_warnings_state(state):
+    """
+    Restores the state of the warnings module when passed an object that was
+    returned by get_warnings_state()
+    """
+    warnings.filters = state[:]
+
+
 def get_runner(settings):
     test_path = settings.TEST_RUNNER.split('.')
     # Allow for Python 2.5 relative paths
diff --git a/tests/regressiontests/cache/tests.py b/tests/regressiontests/cache/tests.py
index 1e0a4046bb..7167e2fbf8 100644
--- a/tests/regressiontests/cache/tests.py
+++ b/tests/regressiontests/cache/tests.py
@@ -16,6 +16,7 @@ from django.core.cache import get_cache
 from django.core.cache.backends.base import InvalidCacheBackendError, CacheKeyWarning
 from django.http import HttpResponse, HttpRequest
 from django.middleware.cache import FetchFromCacheMiddleware, UpdateCacheMiddleware
+from django.test.utils import get_warnings_state, restore_warnings_state
 from django.utils import translation
 from django.utils.cache import patch_vary_headers, get_cache_key, learn_cache_key
 from django.utils.hashcompat import md5_constructor
@@ -379,20 +380,16 @@ class BaseCacheTests(object):
         # manager to test this warning nicely. Since we can't do that
         # yet, the cleanest option is to temporarily ask for
         # CacheKeyWarning to be raised as an exception.
+        _warnings_state = get_warnings_state()
         warnings.simplefilter("error", CacheKeyWarning)
 
-        # memcached does not allow whitespace or control characters in keys
-        self.assertRaises(CacheKeyWarning, self.cache.set, 'key with spaces', 'value')
-        # memcached limits key length to 250
-        self.assertRaises(CacheKeyWarning, self.cache.set, 'a' * 251, 'value')
-
-        # The warnings module has no public API for getting the
-        # current list of warning filters, so we can't save that off
-        # and reset to the previous value, we have to globally reset
-        # it. The effect will be the same, as long as the Django test
-        # runner doesn't add any global warning filters (it currently
-        # does not).
-        warnings.resetwarnings()
+        try:
+            # memcached does not allow whitespace or control characters in keys
+            self.assertRaises(CacheKeyWarning, self.cache.set, 'key with spaces', 'value')
+            # memcached limits key length to 250
+            self.assertRaises(CacheKeyWarning, self.cache.set, 'a' * 251, 'value')
+        finally:
+            restore_warnings_state(_warnings_state)
 
 class DBCacheTests(unittest.TestCase, BaseCacheTests):
     def setUp(self):
diff --git a/tests/regressiontests/templates/loaders.py b/tests/regressiontests/templates/loaders.py
index caa3faa6bc..47cd18ae21 100644
--- a/tests/regressiontests/templates/loaders.py
+++ b/tests/regressiontests/templates/loaders.py
@@ -21,6 +21,7 @@ from django.template import TemplateDoesNotExist, Context
 from django.template.loaders.eggs import load_template_source as lts_egg
 from django.template.loaders.eggs import Loader as EggLoader
 from django.template import loader
+from django.test.utils import get_warnings_state, restore_warnings_state
 
 # Mock classes and objects for pkg_resources functions.
 class MockProvider(pkg_resources.NullProvider):
@@ -67,11 +68,12 @@ class DeprecatedEggLoaderTest(unittest.TestCase):
         })
         self._old_installed_apps = settings.INSTALLED_APPS
         settings.INSTALLED_APPS = []
+        self._warnings_state = get_warnings_state()
         warnings.simplefilter("ignore", PendingDeprecationWarning)
 
     def tearDown(self):
         settings.INSTALLED_APPS = self._old_installed_apps
-        warnings.resetwarnings()
+        restore_warnings_state(self._warnings_state)
 
     def test_existing(self):
         "A template can be loaded from an egg"