I have a setup similar to yours with an app target and local SPM packages, I'm not sure this applies to your case but I came across a similar situation. Try to run the tests with a Debug configuration if you're not doing so already. I've also noticed that debugging code inside a SPM package included in the app was very limited with any configuration name other then Debug because the packages would be compiled without debugging information. I have a set of xcconfig files for diferent environments like "Development" and "Staging" assigned to the correspondent configurations in the project. Then I have a Debug configuration which I assign one of those xcconfigs. Hope this helps.