Generally a +1 from me on the proposal. I have used various forms of testing in the past that would have benefited from attachments such as snapshot tests or unit tests that wanted to attach the logs.
We will also introduce a cross-import overlay with Foundation—that is, a tertiary module that is automatically imported when a test target imports both Foundation and Swift Testing—that includes additional conformances for Foundation types such as
DataandURLand provides support for attaching values that also conform toEncodableorNSSecureCoding.
This section is the only thing that stood out to me. My understanding is that cross-import overlays are not an accepted proposal and currently just a pitch. While the functionality is present in the compiler itself they aren't exposed in any way through Swift PM. I'm personally a bit worried for a proposal to use an unreviewed feature. Additionally, what impact does this have when consuming Testing directly from the package or hypothetically moving Testing out of the toolchain in the future again and making it a package dependency?