The Jenkins job mediawiki-core-code-coverage produces code coverage for MediaWiki core. It is run on a daily basis and takes a while:
It uses to take almost 4 hours to generate and nowadays a bit less than 2 hours which is still a lot. Build time trend:
The huge drop from 220 minutes to 100 minutes is git lg 3d7e37edd08edd4504bff920cc0b0972917f5795..4a975b8099ee11b15421d03be02206935a8422f1 which contains the refactoring of parser tests. Potentially parser tests are no longer participating in the coverage. Filled as T147779 for investigation.
The job runs on Trusty instances with Zend PHP5.5 and XDebug. PHPUnit relies on PHP_CodeCoverage which apparently supports Zend PHP 7.0 and phpdbg, the combination being an order of magnitude faster.