The RelatedArticles tests depends on some other repositories. @bmansurov made a change to CI to have the repository tests with a bunch of other repositories (mediawiki-extensions-*) jobs.
We gave it a try with https://gerrit.wikimedia.org/r/#/c/246818/ but that caused tests of at least Echo and Flow to fail I have reverted CI immediately with https://gerrit.wikimedia.org/r/#/c/246829/
An example test report is https://integration.wikimedia.org/ci/job/mediawiki-extensions-hhvm/35991/testReport/ :
mysql_real_escape_string() expects parameter 1 to be string, array given
I reproduced it locally with Sqlite and just Echo + RelatedArticles.
For Sqlite that ends up falling when calling addQuotes() on an array. I also spotted some warnings such as:
Warning: bin2hex() expects parameter 1 to be string, array given in includes/db/DatabaseSqlite.php on line 817
What I found is that it seems to be caused by the RelatedArticles hook onParserClearState which does:
$parser->getOutput()->setProperty( 'RelatedArticles', array() );
If I comment it out, it is all fine.
To test the behavior, one can propose a dummy patch in Gerrit for RelatedArticles then comment `check experimental`. That will run the mediawiki-extensions-hhvm job and inject RelatedArticles into it.