I'm not sure if this is the right venue to place this but I'd just like to share something I've spent hours on that I could not find documented elsewhere.
I was attempting to run tests via a Build Configuration within TeamCity. I could not get it to work. I had my build agent (Mac mini) set up to be launched as a launch daemon (per the documentation). I was either seeing no tests being run (agent builds the test target but didn't run the tests and marks that step as successful) or xcodebuild would hang if I was logged in as the same user I had the launch daemon set to launch the build agent as.
So after a long time of investigating, I realized that running xctests requires an interactive session (aka a logged in user). For my purposes, a login script that launched the build agent did the trick.
I'm curious as to whether anyone has any other solutions.