Why?

Our merge script requires that PRs be merged with a merge commit to maintain git history and avoid conflicts in the future. Our normal PR process is to squash before merging, usually with auto-merge enabled. Since Github defaults to the last merge method selected, its very easy to accidentally enable auto-squash in this one situation where we really need a merge commit.

Neither Github's branch rulesets nor branch protection rules let us define rules in the context of the HEAD ref, so this PR adds a CI that can.

What?

• add rules.yml to define PR/branch rules that we cannot define in the Github UI
• added Merge script PRs must create merge commits rule to run when auto merge is enabled and when the branch contains /merge-, and check that the auto merge method is 'merge'

Demo

When auto-merge is enabled on a merge PR like stripe/stripe-dotnet#3106, it runs the rule as part of its checks. If the auto-merge method is not 'merge', it fails:

The error provides a brief description about why it failed as a reminder to go fix the auto-merge method:

Once fixed, the merge PR check is green, and everything's good to go:

Note that this must exist in the repo and enabled as a blocking status check to get the full benefit!

See Also