We currently use Travis CI on various repos (https://travis-ci.org/citation-style-language), with e.g. RSpec tests for the https://github.com/citation-style-language/styles and https://github.com/citation-style-language/locales repos for quality control, and webhooks to alert https://github.com/citation-style-language/Sheldon, https://github.com/citation-style-language/distribution-updater, and Zotero of build results.
Sheldon posts GitHub comments to pull requests in our “styles” and “locales” repo to assist contributors. See the posts by csl-bot in https://github.com/citation-style-language/styles/pull/4003 for an example. distribution-updater updates https://github.com/citation-style-language/styles-distribution whenever a Travis build for the “master” branch of https://github.com/citation-style-language/styles completes successfully. (the styles-distribution repo is a bit redundant now that GitHub offers protected branches (https://help.github.com/en/articles/about-protected-branches), but we haven’t bothered making the change yet)