Build error when using toEventually

[AnthonyMDev]

Version: Nimble 13.7.1

When using .toEventually() in an async test, I'm getting this error:

Non-sendable result type 'SyncExpectation<Bool>' cannot be sent from nonisolated context in call to instance method 'toEventually(_:timeout:pollInterval:description:)'

I get this from a statement as simple as: await expect(true).toEventually(beFalse()).

I'm not sure if this is a bug or I'm doing something wrong.

I can get past this by using @preconcurrency import Nimble for now, but it looks like SyncExpectation and probably AsyncExpectation should conform to Sendable to make this error go away.

[dockay]

This seems related to the new Swift 6.2 concurrency feature that Xcode 26 enforces?

[younata]

This has been known for a bit. Nimble does not support Swift 6 language mode yet. There's a lot in polling expectations in particular which rely on XCTest only running 1 test per process. Been working on it, slowly.

For now, yes, use @preconcurrency import Nimble.

[AnthonyMDev]

Thank you for the reply! No pressure on the timeline for this. I maintain a large open source project too, and we are just now getting around to supporting async/await at all. 😅

I just wanted to make sure I wasn't doing something incorrectly and raise the issue.

Follow up question: Should we not be running tests in parallel at all if we are using polling expectations?

[younata]

XCTest's parallel test running works by running spinning up multiple processes to run tests. Each test in those process runs single-threaded. Nimble works with that model without issue.

Swift Testing's parallel test running is in-process, running tests multi-threaded. Polling expectations (toEventually) do not work with that. But to my knowledge, the rest of Nimble works with that model.