Avoid reaching inside the object cache object in tests

[rmccue]

It'd be really fantastically great if WP_UnitTestCase::flush_cache could keep its hands off my internal properties. :)

Right now, flush_cache reaches into $wp_object_cache and messes with a bunch of internal properties:

$wp_object_cache->group_ops = array();
$wp_object_cache->stats = array();
$wp_object_cache->memcache_debug = array();
$wp_object_cache->cache = array();

If we could just not do that, that'd be greaaaat.

[boonebgorges]

Introduced in https://core.trac.wordpress.org/changeset/760/tests

[voldemortensen]

I couldn't find anywhere that was actually setting these properties anyway. I don't know if I'm missing something but I don't see a purpose for these lines. The $wp_object_cache->cache = array(); seems to be redundant as that's what wp_cache_flush does.

[dd32]

@voldemortensen FWIW, those lines are included for external object caches, not the core classes. Those properties, and __remoteset are used by Memcache, but others might use something different (I don't think __remoteset is even used in a published object cache, I think it's only used by the internal wp.com one)

See ​https://plugins.trac.wordpress.org/browser/memcached/tags/2.0.2/object-cache.php#L189 and ​https://plugins.trac.wordpress.org/browser/memcached-redux/tags/0.1.3/object-cache.php#L215

I guess we'd have to add a new method/parameter to do this, and even possibly include the back-compat code here.

[DrewAPicture]

Moving off of the 4.2 milestone as this is a release-independent change.

[spacedmonkey]

@SergeyBiryukov Could we use wp_cache_flush_runtime here?

Trac ticket: https://core.trac.wordpress.org/ticket/31463

LGTM

[spacedmonkey]

In 55741:

Build/Test Tools: Call wp_cache_flush_runtime in WP_UnitTestCase.

In WP_UnitTestCase::flush_cache method, the properties of the global $wp_object_cache object were manaully being reset to flush the cache. The function wp_cache_flush_runtime was added in [52772] and is designed to reset any class properties to default values. Using wp_cache_flush_runtime improve compatibility with third party object caches, as it allows developers to define their own wp_cache_flush_runtime function.

Props rmccue, johnbillion, wonderboymusic, boonebgorges, voldemortensen, dd32, DrewAPicture, tillkruess, spacedmonkey.
Fixes #31463.

Committed https://core.trac.wordpress.org/changeset/55741

[spacedmonkey]

Mentioned in dev note - ​https://make.wordpress.org/core/2023/07/17/improvements-to-the-cache-api-in-wordpress-6-3/