• I have read CONTRIBUTING and have done my best to follow them.

What did you do?

I recently updated my project to use SWIFT_STRICT_CONCURRENCY=targeted. After doing so, Nimble is giving the following warnings when using toEventually():

// Non-sendable type 'SyncExpectation<FooViewModel.State>' returned by implicitly asynchronous call to nonisolated function cannot cross actor boundary

// Passing argument of non-sendable type 'Matcher<FooViewModel.State>' outside of main actor-isolated context may introduce data races

Here's some code to reproduce the problem:

The subject being tested:

@MainActor final class FooViewModel { struct State: Equatable { let val: String } var state: State { State(val: "val") } }

The Spec:

@MainActor final class ExampleTestSpec: AsyncSpec { override class func spec() { var fooVM: FooViewModel! beforeEach { @MainActor in fooVM = FooViewModel() } it("sets states") { @MainActor in // This works fine expect(fooVM.state).to(equal(FooViewModel.State(val: "val"))) } it("eventually sets state") { @MainActor in // This gives two warnings: // Non-sendable type 'SyncExpectation<FooViewModel.State>' returned by implicitly asynchronous call to nonisolated function cannot cross actor boundary // Passing argument of non-sendable type 'Matcher<FooViewModel.State>' outside of main actor-isolated context may introduce data races await expect(fooVM.state).toEventually(equal(FooViewModel.State(val: "val"))) } } }

Reasoning around @MainActor usage: Since we're testing a ViewModel here, we want to isolate everything to run on the main actor.

Please feel free to suggest an alternative way but right now, I think the only feasible workarounds available are:

1. Use @preconcurrency import Nimble to silence the warnings
2. Use @unchecked Sendable to silence the warnings

Neither of the above workarounds are ideal. I'm curious to understand why SyncExpectation and Matcher don't conform to Sendable. Is there a plan to add this conformance soon? If not then what approach would you suggest in this situation?

What did you expect to happen?

I expected no warnings.

What actually happened instead?

I got two warnings around SyncExpectation and Matcher being non-sendable types.

Environment

List the software versions you're using:

• Quick: 7.3.0
• Nimble: 13.1.2
• Xcode Version: 15.1 (15C65)
• Swift Version: 5.9.2

Please also mention which package manager you used and its version. Delete the
other package managers in this list:

• Swift Package Manager: Swift Package Manager - Swift 5.9.0