parts/django/tests/regressiontests/cache/tests.py
changeset 307 c6bca38c1cbf
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/parts/django/tests/regressiontests/cache/tests.py	Sat Jan 08 11:20:57 2011 +0530
@@ -0,0 +1,652 @@
+# -*- coding: utf-8 -*-
+
+# Unit tests for cache framework
+# Uses whatever cache backend is set in the test settings file.
+
+import os
+import shutil
+import tempfile
+import time
+import unittest
+import warnings
+
+from django.conf import settings
+from django.core import management
+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
+from regressiontests.cache.models import Poll, expensive_calculation
+
+# functions/classes for complex data type tests
+def f():
+    return 42
+class C:
+    def m(n):
+        return 24
+
+class DummyCacheTests(unittest.TestCase):
+    # The Dummy cache backend doesn't really behave like a test backend,
+    # so it has different test requirements.
+    def setUp(self):
+        self.cache = get_cache('dummy://')
+
+    def test_simple(self):
+        "Dummy cache backend ignores cache set calls"
+        self.cache.set("key", "value")
+        self.assertEqual(self.cache.get("key"), None)
+
+    def test_add(self):
+        "Add doesn't do anything in dummy cache backend"
+        self.cache.add("addkey1", "value")
+        result = self.cache.add("addkey1", "newvalue")
+        self.assertEqual(result, True)
+        self.assertEqual(self.cache.get("addkey1"), None)
+
+    def test_non_existent(self):
+        "Non-existent keys aren't found in the dummy cache backend"
+        self.assertEqual(self.cache.get("does_not_exist"), None)
+        self.assertEqual(self.cache.get("does_not_exist", "bang!"), "bang!")
+
+    def test_get_many(self):
+        "get_many returns nothing for the dummy cache backend"
+        self.cache.set('a', 'a')
+        self.cache.set('b', 'b')
+        self.cache.set('c', 'c')
+        self.cache.set('d', 'd')
+        self.assertEqual(self.cache.get_many(['a', 'c', 'd']), {})
+        self.assertEqual(self.cache.get_many(['a', 'b', 'e']), {})
+
+    def test_delete(self):
+        "Cache deletion is transparently ignored on the dummy cache backend"
+        self.cache.set("key1", "spam")
+        self.cache.set("key2", "eggs")
+        self.assertEqual(self.cache.get("key1"), None)
+        self.cache.delete("key1")
+        self.assertEqual(self.cache.get("key1"), None)
+        self.assertEqual(self.cache.get("key2"), None)
+
+    def test_has_key(self):
+        "The has_key method doesn't ever return True for the dummy cache backend"
+        self.cache.set("hello1", "goodbye1")
+        self.assertEqual(self.cache.has_key("hello1"), False)
+        self.assertEqual(self.cache.has_key("goodbye1"), False)
+
+    def test_in(self):
+        "The in operator doesn't ever return True for the dummy cache backend"
+        self.cache.set("hello2", "goodbye2")
+        self.assertEqual("hello2" in self.cache, False)
+        self.assertEqual("goodbye2" in self.cache, False)
+
+    def test_incr(self):
+        "Dummy cache values can't be incremented"
+        self.cache.set('answer', 42)
+        self.assertRaises(ValueError, self.cache.incr, 'answer')
+        self.assertRaises(ValueError, self.cache.incr, 'does_not_exist')
+
+    def test_decr(self):
+        "Dummy cache values can't be decremented"
+        self.cache.set('answer', 42)
+        self.assertRaises(ValueError, self.cache.decr, 'answer')
+        self.assertRaises(ValueError, self.cache.decr, 'does_not_exist')
+
+    def test_data_types(self):
+        "All data types are ignored equally by the dummy cache"
+        stuff = {
+            'string'    : 'this is a string',
+            'int'       : 42,
+            'list'      : [1, 2, 3, 4],
+            'tuple'     : (1, 2, 3, 4),
+            'dict'      : {'A': 1, 'B' : 2},
+            'function'  : f,
+            'class'     : C,
+        }
+        self.cache.set("stuff", stuff)
+        self.assertEqual(self.cache.get("stuff"), None)
+
+    def test_expiration(self):
+        "Expiration has no effect on the dummy cache"
+        self.cache.set('expire1', 'very quickly', 1)
+        self.cache.set('expire2', 'very quickly', 1)
+        self.cache.set('expire3', 'very quickly', 1)
+
+        time.sleep(2)
+        self.assertEqual(self.cache.get("expire1"), None)
+
+        self.cache.add("expire2", "newvalue")
+        self.assertEqual(self.cache.get("expire2"), None)
+        self.assertEqual(self.cache.has_key("expire3"), False)
+
+    def test_unicode(self):
+        "Unicode values are ignored by the dummy cache"
+        stuff = {
+            u'ascii': u'ascii_value',
+            u'unicode_ascii': u'Iñtërnâtiônàlizætiøn1',
+            u'Iñtërnâtiônàlizætiøn': u'Iñtërnâtiônàlizætiøn2',
+            u'ascii': {u'x' : 1 }
+            }
+        for (key, value) in stuff.items():
+            self.cache.set(key, value)
+            self.assertEqual(self.cache.get(key), None)
+
+    def test_set_many(self):
+        "set_many does nothing for the dummy cache backend"
+        self.cache.set_many({'a': 1, 'b': 2})
+
+    def test_delete_many(self):
+        "delete_many does nothing for the dummy cache backend"
+        self.cache.delete_many(['a', 'b'])
+
+    def test_clear(self):
+        "clear does nothing for the dummy cache backend"
+        self.cache.clear()
+
+
+class BaseCacheTests(object):
+    # A common set of tests to apply to all cache backends
+    def tearDown(self):
+        self.cache.clear()
+
+    def test_simple(self):
+        # Simple cache set/get works
+        self.cache.set("key", "value")
+        self.assertEqual(self.cache.get("key"), "value")
+
+    def test_add(self):
+        # A key can be added to a cache
+        self.cache.add("addkey1", "value")
+        result = self.cache.add("addkey1", "newvalue")
+        self.assertEqual(result, False)
+        self.assertEqual(self.cache.get("addkey1"), "value")
+
+    def test_non_existent(self):
+        # Non-existent cache keys return as None/default
+        # get with non-existent keys
+        self.assertEqual(self.cache.get("does_not_exist"), None)
+        self.assertEqual(self.cache.get("does_not_exist", "bang!"), "bang!")
+
+    def test_get_many(self):
+        # Multiple cache keys can be returned using get_many
+        self.cache.set('a', 'a')
+        self.cache.set('b', 'b')
+        self.cache.set('c', 'c')
+        self.cache.set('d', 'd')
+        self.assertEqual(self.cache.get_many(['a', 'c', 'd']), {'a' : 'a', 'c' : 'c', 'd' : 'd'})
+        self.assertEqual(self.cache.get_many(['a', 'b', 'e']), {'a' : 'a', 'b' : 'b'})
+
+    def test_delete(self):
+        # Cache keys can be deleted
+        self.cache.set("key1", "spam")
+        self.cache.set("key2", "eggs")
+        self.assertEqual(self.cache.get("key1"), "spam")
+        self.cache.delete("key1")
+        self.assertEqual(self.cache.get("key1"), None)
+        self.assertEqual(self.cache.get("key2"), "eggs")
+
+    def test_has_key(self):
+        # The cache can be inspected for cache keys
+        self.cache.set("hello1", "goodbye1")
+        self.assertEqual(self.cache.has_key("hello1"), True)
+        self.assertEqual(self.cache.has_key("goodbye1"), False)
+
+    def test_in(self):
+        # The in operator can be used to inspet cache contents
+        self.cache.set("hello2", "goodbye2")
+        self.assertEqual("hello2" in self.cache, True)
+        self.assertEqual("goodbye2" in self.cache, False)
+
+    def test_incr(self):
+        # Cache values can be incremented
+        self.cache.set('answer', 41)
+        self.assertEqual(self.cache.incr('answer'), 42)
+        self.assertEqual(self.cache.get('answer'), 42)
+        self.assertEqual(self.cache.incr('answer', 10), 52)
+        self.assertEqual(self.cache.get('answer'), 52)
+        self.assertRaises(ValueError, self.cache.incr, 'does_not_exist')
+
+    def test_decr(self):
+        # Cache values can be decremented
+        self.cache.set('answer', 43)
+        self.assertEqual(self.cache.decr('answer'), 42)
+        self.assertEqual(self.cache.get('answer'), 42)
+        self.assertEqual(self.cache.decr('answer', 10), 32)
+        self.assertEqual(self.cache.get('answer'), 32)
+        self.assertRaises(ValueError, self.cache.decr, 'does_not_exist')
+
+    def test_data_types(self):
+        # Many different data types can be cached
+        stuff = {
+            'string'    : 'this is a string',
+            'int'       : 42,
+            'list'      : [1, 2, 3, 4],
+            'tuple'     : (1, 2, 3, 4),
+            'dict'      : {'A': 1, 'B' : 2},
+            'function'  : f,
+            'class'     : C,
+        }
+        self.cache.set("stuff", stuff)
+        self.assertEqual(self.cache.get("stuff"), stuff)
+
+    def test_cache_read_for_model_instance(self):
+        # Don't want fields with callable as default to be called on cache read
+        expensive_calculation.num_runs = 0
+        Poll.objects.all().delete()
+        my_poll = Poll.objects.create(question="Well?")
+        self.assertEqual(Poll.objects.count(), 1)
+        pub_date = my_poll.pub_date
+        self.cache.set('question', my_poll)
+        cached_poll = self.cache.get('question')
+        self.assertEqual(cached_poll.pub_date, pub_date)
+        # We only want the default expensive calculation run once
+        self.assertEqual(expensive_calculation.num_runs, 1)
+
+    def test_cache_write_for_model_instance_with_deferred(self):
+        # Don't want fields with callable as default to be called on cache write
+        expensive_calculation.num_runs = 0
+        Poll.objects.all().delete()
+        my_poll = Poll.objects.create(question="What?")
+        self.assertEqual(expensive_calculation.num_runs, 1)
+        defer_qs = Poll.objects.all().defer('question')
+        self.assertEqual(defer_qs.count(), 1)
+        self.assertEqual(expensive_calculation.num_runs, 1)
+        self.cache.set('deferred_queryset', defer_qs)
+        # cache set should not re-evaluate default functions
+        self.assertEqual(expensive_calculation.num_runs, 1)
+
+    def test_cache_read_for_model_instance_with_deferred(self):
+        # Don't want fields with callable as default to be called on cache read
+        expensive_calculation.num_runs = 0
+        Poll.objects.all().delete()
+        my_poll = Poll.objects.create(question="What?")
+        self.assertEqual(expensive_calculation.num_runs, 1)
+        defer_qs = Poll.objects.all().defer('question')
+        self.assertEqual(defer_qs.count(), 1)
+        self.cache.set('deferred_queryset', defer_qs)
+        self.assertEqual(expensive_calculation.num_runs, 1)
+        runs_before_cache_read = expensive_calculation.num_runs
+        cached_polls = self.cache.get('deferred_queryset')
+        # We only want the default expensive calculation run on creation and set
+        self.assertEqual(expensive_calculation.num_runs, runs_before_cache_read)
+
+    def test_expiration(self):
+        # Cache values can be set to expire
+        self.cache.set('expire1', 'very quickly', 1)
+        self.cache.set('expire2', 'very quickly', 1)
+        self.cache.set('expire3', 'very quickly', 1)
+
+        time.sleep(2)
+        self.assertEqual(self.cache.get("expire1"), None)
+
+        self.cache.add("expire2", "newvalue")
+        self.assertEqual(self.cache.get("expire2"), "newvalue")
+        self.assertEqual(self.cache.has_key("expire3"), False)
+
+    def test_unicode(self):
+        # Unicode values can be cached
+        stuff = {
+            u'ascii': u'ascii_value',
+            u'unicode_ascii': u'Iñtërnâtiônàlizætiøn1',
+            u'Iñtërnâtiônàlizætiøn': u'Iñtërnâtiônàlizætiøn2',
+            u'ascii': {u'x' : 1 }
+            }
+        for (key, value) in stuff.items():
+            self.cache.set(key, value)
+            self.assertEqual(self.cache.get(key), value)
+
+    def test_binary_string(self):
+        # Binary strings should be cachable
+        from zlib import compress, decompress
+        value = 'value_to_be_compressed'
+        compressed_value = compress(value)
+        self.cache.set('binary1', compressed_value)
+        compressed_result = self.cache.get('binary1')
+        self.assertEqual(compressed_value, compressed_result)
+        self.assertEqual(value, decompress(compressed_result))
+
+    def test_set_many(self):
+        # Multiple keys can be set using set_many
+        self.cache.set_many({"key1": "spam", "key2": "eggs"})
+        self.assertEqual(self.cache.get("key1"), "spam")
+        self.assertEqual(self.cache.get("key2"), "eggs")
+
+    def test_set_many_expiration(self):
+        # set_many takes a second ``timeout`` parameter
+        self.cache.set_many({"key1": "spam", "key2": "eggs"}, 1)
+        time.sleep(2)
+        self.assertEqual(self.cache.get("key1"), None)
+        self.assertEqual(self.cache.get("key2"), None)
+
+    def test_delete_many(self):
+        # Multiple keys can be deleted using delete_many
+        self.cache.set("key1", "spam")
+        self.cache.set("key2", "eggs")
+        self.cache.set("key3", "ham")
+        self.cache.delete_many(["key1", "key2"])
+        self.assertEqual(self.cache.get("key1"), None)
+        self.assertEqual(self.cache.get("key2"), None)
+        self.assertEqual(self.cache.get("key3"), "ham")
+
+    def test_clear(self):
+        # The cache can be emptied using clear
+        self.cache.set("key1", "spam")
+        self.cache.set("key2", "eggs")
+        self.cache.clear()
+        self.assertEqual(self.cache.get("key1"), None)
+        self.assertEqual(self.cache.get("key2"), None)
+
+    def test_long_timeout(self):
+        '''
+        Using a timeout greater than 30 days makes memcached think
+        it is an absolute expiration timestamp instead of a relative
+        offset. Test that we honour this convention. Refs #12399.
+        '''
+        self.cache.set('key1', 'eggs', 60*60*24*30 + 1) #30 days + 1 second
+        self.assertEqual(self.cache.get('key1'), 'eggs')
+
+        self.cache.add('key2', 'ham', 60*60*24*30 + 1)
+        self.assertEqual(self.cache.get('key2'), 'ham')
+
+        self.cache.set_many({'key3': 'sausage', 'key4': 'lobster bisque'}, 60*60*24*30 + 1)
+        self.assertEqual(self.cache.get('key3'), 'sausage')
+        self.assertEqual(self.cache.get('key4'), 'lobster bisque')
+
+    def perform_cull_test(self, initial_count, final_count):
+        """This is implemented as a utility method, because only some of the backends
+        implement culling. The culling algorithm also varies slightly, so the final
+        number of entries will vary between backends"""
+        # Create initial cache key entries. This will overflow the cache, causing a cull
+        for i in range(1, initial_count):
+            self.cache.set('cull%d' % i, 'value', 1000)
+        count = 0
+        # Count how many keys are left in the cache.
+        for i in range(1, initial_count):
+            if self.cache.has_key('cull%d' % i):
+                count = count + 1
+        self.assertEqual(count, final_count)
+
+    def test_invalid_keys(self):
+        """
+        All the builtin backends (except memcached, see below) should warn on
+        keys that would be refused by memcached. This encourages portable
+        caching code without making it too difficult to use production backends
+        with more liberal key rules. Refs #6447.
+
+        """
+        # On Python 2.6+ we could use the catch_warnings context
+        # 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)
+
+        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):
+        # Spaces are used in the table name to ensure quoting/escaping is working
+        self._table_name = 'test cache table'
+        management.call_command('createcachetable', self._table_name, verbosity=0, interactive=False)
+        self.cache = get_cache('db://%s?max_entries=30' % self._table_name)
+
+    def tearDown(self):
+        from django.db import connection
+        cursor = connection.cursor()
+        cursor.execute('DROP TABLE %s' % connection.ops.quote_name(self._table_name))
+
+    def test_cull(self):
+        self.perform_cull_test(50, 29)
+
+class LocMemCacheTests(unittest.TestCase, BaseCacheTests):
+    def setUp(self):
+        self.cache = get_cache('locmem://?max_entries=30')
+
+    def test_cull(self):
+        self.perform_cull_test(50, 29)
+
+# memcached backend isn't guaranteed to be available.
+# To check the memcached backend, the test settings file will
+# need to contain a CACHE_BACKEND setting that points at
+# your memcache server.
+if settings.CACHE_BACKEND.startswith('memcached://'):
+    class MemcachedCacheTests(unittest.TestCase, BaseCacheTests):
+        def setUp(self):
+            self.cache = get_cache(settings.CACHE_BACKEND)
+
+        def test_invalid_keys(self):
+            """
+            On memcached, we don't introduce a duplicate key validation
+            step (for speed reasons), we just let the memcached API
+            library raise its own exception on bad keys. Refs #6447.
+
+            In order to be memcached-API-library agnostic, we only assert
+            that a generic exception of some kind is raised.
+
+            """
+            # memcached does not allow whitespace or control characters in keys
+            self.assertRaises(Exception, self.cache.set, 'key with spaces', 'value')
+            # memcached limits key length to 250
+            self.assertRaises(Exception, self.cache.set, 'a' * 251, 'value')
+
+
+class FileBasedCacheTests(unittest.TestCase, BaseCacheTests):
+    """
+    Specific test cases for the file-based cache.
+    """
+    def setUp(self):
+        self.dirname = tempfile.mkdtemp()
+        self.cache = get_cache('file://%s?max_entries=30' % self.dirname)
+
+    def test_hashing(self):
+        """Test that keys are hashed into subdirectories correctly"""
+        self.cache.set("foo", "bar")
+        keyhash = md5_constructor("foo").hexdigest()
+        keypath = os.path.join(self.dirname, keyhash[:2], keyhash[2:4], keyhash[4:])
+        self.assert_(os.path.exists(keypath))
+
+    def test_subdirectory_removal(self):
+        """
+        Make sure that the created subdirectories are correctly removed when empty.
+        """
+        self.cache.set("foo", "bar")
+        keyhash = md5_constructor("foo").hexdigest()
+        keypath = os.path.join(self.dirname, keyhash[:2], keyhash[2:4], keyhash[4:])
+        self.assert_(os.path.exists(keypath))
+
+        self.cache.delete("foo")
+        self.assert_(not os.path.exists(keypath))
+        self.assert_(not os.path.exists(os.path.dirname(keypath)))
+        self.assert_(not os.path.exists(os.path.dirname(os.path.dirname(keypath))))
+
+    def test_cull(self):
+        self.perform_cull_test(50, 28)
+
+class CustomCacheKeyValidationTests(unittest.TestCase):
+    """
+    Tests for the ability to mixin a custom ``validate_key`` method to
+    a custom cache backend that otherwise inherits from a builtin
+    backend, and override the default key validation. Refs #6447.
+
+    """
+    def test_custom_key_validation(self):
+        cache = get_cache('regressiontests.cache.liberal_backend://')
+
+        # this key is both longer than 250 characters, and has spaces
+        key = 'some key with spaces' * 15
+        val = 'a value'
+        cache.set(key, val)
+        self.assertEqual(cache.get(key), val)
+
+class CacheUtils(unittest.TestCase):
+    """TestCase for django.utils.cache functions."""
+
+    def setUp(self):
+        self.path = '/cache/test/'
+        self.old_settings_key_prefix = settings.CACHE_MIDDLEWARE_KEY_PREFIX
+        self.old_middleware_seconds = settings.CACHE_MIDDLEWARE_SECONDS
+        self.orig_use_i18n = settings.USE_I18N
+        settings.CACHE_MIDDLEWARE_KEY_PREFIX = 'settingsprefix'
+        settings.CACHE_MIDDLEWARE_SECONDS = 1
+        settings.USE_I18N = False
+
+    def tearDown(self):
+        settings.CACHE_MIDDLEWARE_KEY_PREFIX = self.old_settings_key_prefix
+        settings.CACHE_MIDDLEWARE_SECONDS = self.old_middleware_seconds
+        settings.USE_I18N = self.orig_use_i18n
+
+    def _get_request(self, path):
+        request = HttpRequest()
+        request.META = {
+            'SERVER_NAME': 'testserver',
+            'SERVER_PORT': 80,
+        }
+        request.path = request.path_info = "/cache/%s" % path
+        return request
+
+    def test_patch_vary_headers(self):
+        headers = (
+            # Initial vary, new headers, resulting vary.
+            (None, ('Accept-Encoding',), 'Accept-Encoding'),
+            ('Accept-Encoding', ('accept-encoding',), 'Accept-Encoding'),
+            ('Accept-Encoding', ('ACCEPT-ENCODING',), 'Accept-Encoding'),
+            ('Cookie', ('Accept-Encoding',), 'Cookie, Accept-Encoding'),
+            ('Cookie, Accept-Encoding', ('Accept-Encoding',), 'Cookie, Accept-Encoding'),
+            ('Cookie, Accept-Encoding', ('Accept-Encoding', 'cookie'), 'Cookie, Accept-Encoding'),
+            (None, ('Accept-Encoding', 'COOKIE'), 'Accept-Encoding, COOKIE'),
+            ('Cookie,     Accept-Encoding', ('Accept-Encoding', 'cookie'), 'Cookie, Accept-Encoding'),
+            ('Cookie    ,     Accept-Encoding', ('Accept-Encoding', 'cookie'), 'Cookie, Accept-Encoding'),
+        )
+        for initial_vary, newheaders, resulting_vary in headers:
+            response = HttpResponse()
+            if initial_vary is not None:
+                response['Vary'] = initial_vary
+            patch_vary_headers(response, newheaders)
+            self.assertEqual(response['Vary'], resulting_vary)
+
+    def test_get_cache_key(self):
+        request = self._get_request(self.path)
+        response = HttpResponse()
+        key_prefix = 'localprefix'
+        # Expect None if no headers have been set yet.
+        self.assertEqual(get_cache_key(request), None)
+        # Set headers to an empty list.
+        learn_cache_key(request, response)
+        self.assertEqual(get_cache_key(request), 'views.decorators.cache.cache_page.settingsprefix.a8c87a3d8c44853d7f79474f7ffe4ad5.d41d8cd98f00b204e9800998ecf8427e')
+        # Verify that a specified key_prefix is taken in to account.
+        learn_cache_key(request, response, key_prefix=key_prefix)
+        self.assertEqual(get_cache_key(request, key_prefix=key_prefix), 'views.decorators.cache.cache_page.localprefix.a8c87a3d8c44853d7f79474f7ffe4ad5.d41d8cd98f00b204e9800998ecf8427e')
+
+    def test_learn_cache_key(self):
+        request = self._get_request(self.path)
+        response = HttpResponse()
+        response['Vary'] = 'Pony'
+        # Make sure that the Vary header is added to the key hash
+        learn_cache_key(request, response)
+        self.assertEqual(get_cache_key(request), 'views.decorators.cache.cache_page.settingsprefix.a8c87a3d8c44853d7f79474f7ffe4ad5.d41d8cd98f00b204e9800998ecf8427e')
+
+class CacheI18nTest(unittest.TestCase):
+
+    def setUp(self):
+        self.orig_cache_middleware_seconds = settings.CACHE_MIDDLEWARE_SECONDS
+        self.orig_cache_middleware_key_prefix = settings.CACHE_MIDDLEWARE_KEY_PREFIX
+        self.orig_cache_backend = settings.CACHE_BACKEND
+        self.orig_use_i18n = settings.USE_I18N
+        self.orig_languages =  settings.LANGUAGES
+        settings.LANGUAGES = (
+                ('en', 'English'),
+                ('es', 'Spanish'),
+        )
+        settings.CACHE_MIDDLEWARE_KEY_PREFIX = 'settingsprefix'
+        self.path = '/cache/test/'
+
+    def tearDown(self):
+        settings.CACHE_MIDDLEWARE_SECONDS = self.orig_cache_middleware_seconds
+        settings.CACHE_MIDDLEWARE_KEY_PREFIX = self.orig_cache_middleware_key_prefix
+        settings.CACHE_BACKEND = self.orig_cache_backend
+        settings.USE_I18N = self.orig_use_i18n
+        settings.LANGUAGES = self.orig_languages
+        translation.deactivate()
+
+    def _get_request(self):
+        request = HttpRequest()
+        request.META = {
+            'SERVER_NAME': 'testserver',
+            'SERVER_PORT': 80,
+        }
+        request.path = request.path_info = self.path
+        return request
+
+    def _get_request_cache(self):
+        request = HttpRequest()
+        request.META = {
+            'SERVER_NAME': 'testserver',
+            'SERVER_PORT': 80,
+        }
+        request.path = request.path_info = self.path
+        request._cache_update_cache = True
+        request.method = 'GET'
+        request.session = {}
+        return request
+
+    def test_cache_key_i18n(self):
+        settings.USE_I18N = True
+        request = self._get_request()
+        lang = translation.get_language()
+        response = HttpResponse()
+        key = learn_cache_key(request, response)
+        self.assertTrue(key.endswith(lang), "Cache keys should include the language name when i18n is active")
+        key2 = get_cache_key(request)
+        self.assertEqual(key, key2)
+
+    def test_cache_key_no_i18n (self):
+        settings.USE_I18N = False
+        request = self._get_request()
+        lang = translation.get_language()
+        response = HttpResponse()
+        key = learn_cache_key(request, response)
+        self.assertFalse(key.endswith(lang), "Cache keys shouldn't include the language name when i18n is inactive")
+
+    def test_middleware(self):
+        def set_cache(request, lang, msg):
+            translation.activate(lang)
+            response = HttpResponse()
+            response.content= msg
+            return UpdateCacheMiddleware().process_response(request, response)
+
+        settings.CACHE_MIDDLEWARE_SECONDS = 60
+        settings.CACHE_MIDDLEWARE_KEY_PREFIX="test"
+        settings.CACHE_BACKEND='locmem:///'
+        settings.USE_I18N = True
+        en_message ="Hello world!"
+        es_message ="Hola mundo!"
+
+        request = self._get_request_cache()
+        set_cache(request, 'en', en_message)
+        get_cache_data = FetchFromCacheMiddleware().process_request(request)
+        # Check that we can recover the cache
+        self.assertNotEqual(get_cache_data.content, None)
+        self.assertEqual(en_message, get_cache_data.content)
+        # change the session language and set content
+        request = self._get_request_cache()
+        set_cache(request, 'es', es_message)
+        # change again the language
+        translation.activate('en')
+        # retrieve the content from cache
+        get_cache_data = FetchFromCacheMiddleware().process_request(request)
+        self.assertEqual(get_cache_data.content, en_message)
+        # change again the language
+        translation.activate('es')
+        get_cache_data = FetchFromCacheMiddleware().process_request(request)
+        self.assertEqual(get_cache_data.content, es_message)
+
+if __name__ == '__main__':
+    unittest.main()