These are making it hard for developers to find what the real issue is when they look at a build failure, especially if they're less experienced with PHPUnit or MW.
These warnings weren't there until a few weeks ago, which suggests it is either a recent regression due to a change in the test suite, or a pre-existing mistake that the recent PHPUnit upgrade started noticing and warning us about.
13) Wikibase\Client\Tests\ClientParserOutputDataUpdaterTest::testUpdateItemIdProperty The optional $checkForObjectIdentity parameter of assertContains() is deprecated and will be removed in PHPUnit 9. Refactor your test to use assertContainsEquals() instead. /workspace/src/maintenance/doMaintenance.php:99
Acceptance Criteria:
- All tests in Wikibase\Client\Tests\ClientParserOutputDataUpdaterTest pass and do not generate PHPUnit warnings