There was a tech talk many years ago when one of the github engineers talked about how fast the github CI tests were (this was way before the microsoft aquisition). Literally seconds. I wonder if they're still that fast.
They absolutely are not. Hundreds of thousands of Ruby tests end up being pretty slow to execute. The CI machines have all dependencies pre-cached and different tests are parallelized across multiple VMs, yet still a full suite takes ~12 minutes.
