Following on from the earlier Custom Execution Traits pitch, @smontgomery has made a number of noteworthy updates to the proposal, now called "Test Scoping Traits". The motivation is unchanged, aiming to provide API for test and library authors to encapsulate test behavior customizations as traits, which can be opted into by applying the trait to the specific tests and suites and require it.
Please read the full proposal for the details of the latest shape of the API and provide any additional feedback here! We are interested in including this API in the Swift 6.1 release.
Brian