Created a new project with Xcode 16.0.
Added Nimble (13.5.0) to the project's Package Dependencies via SPM.
Ensured Nimble library is linked on both the unit and UI test targets.
The issue occurs when running tests with Nimble imported into a UI test target file (e.g. IssueDemo1157UITests.swift).
When trying to launch the tests in such a UITest file, the message is displayed briefly: Missing required module 'Testing'.
If you remove the import Nimble and simple assertion expect(app.staticTexts["Hello, World!"].exists).to(beTrue()), you can confirm that Unit tests (e.g. IssueDemo1157Tests.swift) can still import and use the Nimble testing library as expected.