1.1 Test framework fails if CACHE_BACKEND = dummy

[fgasperino]

1.1 seems to fail built-in contrib/sessions/test.py if the cache api is enabled, but set to dummy.

CACHE_BACKEND = 'dummy:///'
#CACHE_BACKEND = "locmem:///?timeout=300&max_entries=1000"

vs

#CACHE_BACKEND = 'dummy:///'
CACHE_BACKEND = "locmem:///?timeout=300&max_entries=1000"

Tests:

======================================================================
FAIL: Doctest: django.contrib.sessions.tests

---

Traceback (most recent call last):

File "/home/franco/lib/python2.6/site-packages/django/test/_doctest.py", line 2180, in runTest

raise self.failureException(self.format_failure(new.getvalue()))

AssertionError: Failed doctest test for django.contrib.sessions.tests

File "/home/franco/lib/python2.6/site-packages/django/contrib/sessions/tests.py", line 0, in tests

---

File "/home/franco/lib/python2.6/site-packages/django/contrib/sessions/tests.py", line 166, in django.contrib.sessions.tests
Failed example:

cache_session.exists(cache_session.session_key)

Expected:

True

Got:

False

---

File "/home/franco/lib/python2.6/site-packages/django/contrib/sessions/tests.py", line 188, in django.contrib.sessions.tests
Failed example:

cache_session.exists(key)

Expected:

True

Got:

False

vs

---

Ran 36 tests in 1.284s

OK
Destroying test database...

[Russell Keith-Magee]

Confirmed that these tests fail - however, it's not entirely surprising.

The cache session backend uses the cache to store the session data. The dummy cache backend is pretty much, by definition, a cache that remembers nothing. The test is validating that session data has been stored - and the dummy cache doesn't do that. Ergo, failure.

I presume you are reporting this because you have a project that is (legitimately) using sessions with the db (or other non-cache) session backend, and is using the dummy cache, either for testing or because you haven't hit the need for caching yet. This configuration will introduce a failure into the project test suite even though there isn't actually anything wrong.

This is an example of a bigger problem that we need to address with Django's testing - the difference between application release testing and project integration testing. This is something I'm hoping to address in the v1.2 timeframe.

[Russell Keith-Magee]

Duplicate of #10853