Inline snaphots do not update when ran in vs code or terminal with swift tests when using new swift-testing

[doozMen]

Describe the bug
See reproducer project https://github.com/doozMen/swift-snapshot-xcodebuild

To Reproduce

The reproducer project has description in readme.md. But in short

1. make an inline snaphot test using swift testing
2. set recording to .all or parameter record: true
3. run swift test

   note: nothing happens

4. run `xcodebuild -scheme <#package#> test -destination "platform=macOS" -quiet

note: test is updated

Expected behavior

Both inline and file tests should update, but they do not

Environment

• swift-snapshot-testing version 1.17.6
• Xcode 16.1
• Swift 6.0.2
• OS: macOS 15

[mbrandonw]

Hi @doozMen, the snapshot recording mechanism depends on XCTestObservationCenter of which Swift Testing has no version right now. They are aware of the issue, but without this there isn't much we can do. Recording for inline snapshots will just need to be done through Xcode for the time being.

Since this isn't an issue with the library I am going to convert it to a discussion. Please feel free to continue the conversation over there!

[mbrandonw]

We could provide custom logic for Swift Testing and write out inline snapshots after every test run instead of all at once at the end of the test suite. But then that would also force tests to be run in serial because by default Swift Testing tests run in parallel and that could make it so that multiple recording tests are writing to the same file at once.

[mbrandonw]

Sorry, after playing with this a bit I don't think it's possible to actually write inline snapshots one at a time. It really does seem to need to be done all at once at the end of the test run, and so we are stuck waiting for Swift Testing support.