GitHub has released octocatalog-diff, an open-source tool designed to optimize the testing of Puppet code by enabling developers to preview changes across various roles without directly accessing the Puppet master. This tool, which originated as an internal solution to expedite GitHub's Puppet code testing, performs a "catalog difference" test in under three minutes, significantly reducing manual testing time and enhancing deployment confidence. Unlike other existing Puppet testing methods that require extensive access and manual oversight, octocatalog-diff allows developers to see the impact of their code changes efficiently, thereby facilitating quicker iterations and minimizing the risk of unexpected side effects. The tool's features include catalog comparison between different Git branches, prediction of differences due to fact changes, caching for faster subsequent runs, and the ability to ignore known changes. It has been instrumental in GitHub's major Puppet upgrades and transitions, and it is now offered to the community under the MIT license, inviting contributions to enhance its functionality and compatibility.