[jrockway]

I guess TAP presubmit might be a merge queue... but it seems different from this. There was no requirement that some mechanical system checked that tests passed before your merged your CL. You could merge any code whenever it was approved. If you felt like running the tests, good for you. TAP presubmit is just that mechanical system that runs your tests before executing the merge. That seems like traditional CI to me, not a merge queue.

Jenkins with a Github plugin behaves almost exactly like this system. Every PR basically has tests run 3 times; once for the branch that the PR is on, once for your branch merged to master, and then once after you do the merge and submit it. TAP presubmit did the "once for your branch" and TAP did the post-merge CI.

TAP presubmit didn't really check that the resulting merge was sound, so you would see TAP presubmit pass, your change get merged, and then have the build break anyway because of the race condition. A merge queue would not have this race condition... so I'm not sure Shopify has one either. The more I think about it the more it sounds like they just rewrote Jenkins. (And for that, I don't blame them.)

[glennpratt]

I have never seen anyone automate what Bors does with Jenkins and have anything approaching decent UX. The closest I've ever seen is a permanent stage branch that sometimes has automatic promotion, little integration with reviews and inevitably breaks every few weeks until some poor soul debugs it.