For T342763, @Urbanecm proposed a patch to Quibble to have it spin up a second database ( https://gerrit.wikimedia.org/r/c/integration/quibble/+/949986 ).

If at all possible, I'd like to avoid adding that to Quibble in favor of using MediaWiki system to simulate a secondary database using a prefix or cloning the DB. I apparently gave it a try at https://gerrit.wikimedia.org/r/c/mediawiki/core/+/951950/1/tests/phpunit/includes/specials/SpecialUserRightsTest.php :

$primaryDB = wfGetDB( DB_PRIMARY );
$externalDBname = $primaryDB->getDBname() . '-externaldb';

$dbClone = new CloneDatabase( $primaryDB, [
        // User related tables
        'user', 'user_groups', 'user_properties', 'actor',
    ],
    'externaldb',
    $primaryDB->tablePrefix(), // unittest_
);
$dbClone->useTemporaryTables( true );
$dbClone->cloneTableStructure();

But that leads to a mysterious failure:

Wikimedia\Rdbms\DBUnexpectedError:

Cannot directly change the selected DB domain; any underlying connection handle is owned by a LoadBalancer instance and possibly shared with other callers. LoadBalancer automatically manages DB domain re-selection of unused handles.

In T379925#10362231, @hashar wrote:

For T342763, @Urbanecm proposed a patch to Quibble to have it spin up a second database ( https://gerrit.wikimedia.org/r/c/integration/quibble/+/949986 ).

If at all possible, I'd like to avoid adding that to Quibble in favor of using MediaWiki system to simulate a secondary database using a prefix or cloning the DB.

@aaron, do you think this might be attainable in CI?

In T379925#10370224, @kostajh wrote:

In T379925#10362231, @hashar wrote:

For T342763, @Urbanecm proposed a patch to Quibble to have it spin up a second database ( https://gerrit.wikimedia.org/r/c/integration/quibble/+/949986 ).

If at all possible, I'd like to avoid adding that to Quibble in favor of using MediaWiki system to simulate a secondary database using a prefix or cloning the DB.

@aaron, do you think this might be attainable in CI?

I think so. It might depend on the situation. I'm thinking of the types of scenarios here:

• Connecting to a foreign wiki domain: we can make the domains differ only by table prefix and clone those ones too (e.g. 'awiki_revision' cloned to 'unittest_awiki_revision').
• Connecting to a virtual domain for global data: we can make the virtual domain point to the main db with a different prefix and built of the logic above.

The difficulty is that MediaWikiIntegrationTestCase would have to invoke CloneDatabase on the remote domains (e.g. 'awiki'/'bwiki'/'global'...maybe they could be hardcoded), which means that listOriginalTables() would have to be invoked a few times and support some kind of prefix parameter. All the ChangedTablesTracker stuff would also have to be checked for all the remote domains to reset tables.

Change #1309233 had a related patch set uploaded (by Kosta Harlan; author: Kosta Harlan):

[mediawiki/core@master] tests: Support a foreign wiki database in integration tests

https://gerrit.wikimedia.org/r/1309233