How does the merge queue work?

[george-cosma]

I have attempted to play around with github's new merge queue system, but I must say I am confused as to how it should function. Here's what I attempted to do, and what the outcomes were.

Configuration

First, I've created a new branch named queue-test and created a new rule to enable the merge queue. Here is the (default) configuration.

First attempt

At first, the state of queue-test was that of the main branch, aka no CI ruleset implemented. When I created pull request #10 with a failing test, it did not show up any CI issues. This was as expected as neither that branch, nor the queue-test branch had any CI actions defined.

Afterwards, I created and merged PR #11 which (should) enable the CI actions to be enabled in the merge queue.
I have then merged PR #10, and it had merged with no issues.

Note the presence of only 1 button after the merge happened. This will be relevant later

Second attempt

I decided to revert PR #10, thus creating PR #12. This required me to make the push to the merge queue, and it succeeded, as expected.

Note the fact this has two buttons. When clicking view details I get informed that all tests passed.

My hypothesis was because PR #10 did not have the same (or any) CI actions as those in the target branch, the checks were getting skipped. As such, I created a new branch in my own fork which had as base queue-test. I then created PR #13 and merged it.
The PR was in the merge queue for a handful of seconds, and was pushed almost immediately, even though PR #13 failed all checks.

While almost certainly no PR with a failing CI test would get put into the merge queue manually, why wouldn't the merge queue refuse to merge?
Is this intended behavior, or am I missing something?

[alexandruradovici]

We had similar issues with merge queue, they are still in beta 😄 . We have to enable require status checks to actually make the merge queue to run something.

[george-cosma]

Oh wow! I did not expect it to be part of a different setting altogether, though I guess in hindsight it does make sense 😅. Thank you!

After enabling this options, things seem to be working as expected. Now the PRs in the merge queue are properly checked.

Here are the checks for PR #15 :