In the UI Test suite's setup, we added code to write out our file with desired starting state.
UI test code runs in a separate process from your app, so I suspect what’s going on here is that this code is writing the file to a different container than the target app is reading from. You should be able to confirm this by logging the paths used by both the writing and reading code.
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Quinn “The Eskimo!”
Apple Developer Relations, Developer Technical Support, Core OS/Hardware
let myEmail = "eskimo" + "1" + "@apple.com"
Thank you, Quinn. That is indeed what is happening. Unlike unit tests which effectively use the main app target, the UI tests appear to create and then launch some sort of other app/process as you mention.
I've got the backup plan in place, so we're good-to-go. Perhaps in the future, the UI test bundle will use the same mechanics as a unit test bundle. Will file a feature request later today.