I read http://blog.bitrise.io/2016/09/21/xcode-8-and-automatic-code-signing.html but realized that I don’t actually need the IPA build artifact. I just want to know if the tests pass, and targets build.
Is there a built step I can use to build a project without needing code-signing? A bit like the tests step?
Absolutely, and exactly 
The Xcode Test step (the one you linked) doesn’t require code signing, so you can use that for this.
A bit of technical information/note: this is only true if you don’t set your project to require code signing for running the tests. By default when you generate an Xcode project in Xcode.app it configures it this way, that no code signing is required to run the tests, but this can be changed. Hopefully you did not, and so Xcode Test should pass without any code signing files uploaded
If you have any questions, just let us know!
Right, so the tests step is working great!
I also want to build the project target, without code signing. Perhaps by building it for the simulator?
To put it another way, I’d like to avoid the hassle of us needing to upload code signing certificates to Bitrise, since we don’t need to actually run the build artifact on any devices. Any way to achieve that?
Test does build the project target 
Another thing you can do/try is to use a Script step and run any xcodebuild command you like, with any parameter you want.
Our Xcode steps do the same, they just map your inputs/configs to xcodebuild params (well, ok, the steps have a bit more utility functionality, like collecting artifacts in case of Xcode Archive, but if you don’t need those, you can simply run xcodebuild yourself the way you want to).
Ah. So some targets had related test targets, but not others.
If all targets have test targets (which they should anyway) then we can configure Bitrise steps for each, so all the targets will then be built too, which I think is what I want 
Thanks for your help!
Correct. You can test this in Xcode.app on your Mac, the Xcode steps will call xcodebuild which will simply use your Xcode project configs, so it’s pretty much the same as if you’d click “Test” in Xcode.app