#27124: caches_setting_for_tests passes cull related options to memcached tests
--------------------------------------+--------------------
Reporter: edmorley | Owner: nobody
Type: Cleanup/optimization | Status: new
Component: Core (Cache system) | Version: master
Severity: Normal | Keywords:
Triage Stage: Unreviewed | Has patch: 0
Easy pickings: 0 | UI/UX: 0
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The cache tests have a helper named `caches_setting_for_tests()`
([https://github.com/django/django/blob/989f6108d349e0eebdc5ad26b5cb4e882cb32e47/tests/cache/tests.py#L242-L253
source]), that generates the config that is used to override `CACHES` at
various points during the test run.
However it uses `_caches_setting_base`, which contains cache `OPTIONS`
such as `MAX_ENTRIES` and `CULL_FREQUENCY` that are only relevant to the
locmem, filesystem and database backends
([https://docs.djangoproject.com/en/1.9/topics/cache/#cache-arguments
docs]).
This is problematic, since in #20892 we're going to start passing the
contents of `OPTIONS` verbatim to the memcache client constructors, which
causes the tests to fail like so:
{{{
ERROR: test_memcached_uses_highest_pickle_version
(cache.tests.MemcachedCacheTests)
----------------------------------------------------------------------
Traceback (most recent call last):
File "/home/vagrant/src/_todo/django/tests/cache/tests.py", line 1198,
in test_memcached_uses_highest_pickle_version
self.assertEqual(caches[cache_key]._cache.pickleProtocol,
File
"/home/vagrant/src/_todo/django/django/core/cache/backends/memcached.py",
line 169, in _cache
self._client = self._lib.Client(self._servers, **client_kwargs)
TypeError: __init__() got an unexpected keyword argument 'MAX_ENTRIES'
}}}
As such, the cache tests need to be adjusted to only pass those options to
the backends that support them.
One way of doing this might be for `caches_setting_for_tests()` to take an
additional `include_cull_settings` bool parameter, which would determine
whether the problematic `cull` and `zero_cull` cache keys
([https://github.com/django/django/blob/989f6108d349e0eebdc5ad26b5cb4e882cb32e47/tests/cache/tests.py#L237-L238
source]) were included. This parameter would default to `True`, but then
be set to `False` in `MemcachedCacheTests`.
Thoughts?
Many thanks :-)
--
Ticket URL: <https://code.djangoproject.com/ticket/27124>
Django <https://code.djangoproject.com/>
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