The [[https://www.mediawiki.org/wiki/Extension:CampaignEvents | CampaignEvents ]] extension is enabled in [[https://extloc.toolforge.org/extensions/CampaignEvents | several production wikis ]], including some of the largest. However, the extension isn't [[https://www.mediawiki.org/wiki/Continuous_integration/Tutorials/Adding_your_extension_to_the_shared_gate_job | gated ]], which sometimes results in unexpected CI breakage. Over the last 3 weeks, we've had T378780 and [[https://gerrit.wikimedia.org/r/c/mediawiki/extensions/CampaignEvents/+/1094455 | r1094455]]. So, I'm proposing that the extension be added to the gate. The extension's PHPUnit suite runs in 5 seconds locally, and we don't have too many e2e tests, so the impact on build times should be minimal.
The [[https://www.mediawiki.org/wiki/Extension:CampaignEvents | WikimediaCampaignEvents ]] is a small sub-extension with additional Wikimedia-specific features. I'm proposing that we add it to the gate as well, to test the full set of features enabled in production.