Nimble Next

[younata]

This represents the work for the Nimble 13 Next version.

The idea is to keep this as a draft PR until it's ready. Nimble 13 Next betas will source from this PR.

Work for the next minor version of Nimble will continue to target main, and I'll regularly rebase this PR on top of main to keep it in sync.

Once I feel like we're ready to release this, I'll merge this PR into main.

Contents:

• Make expect+async and AsyncExpression conform to Sendable #1067
• Make expect for async closures take in Sendable closures #1070
• Make the async variants of expect require sendable values #1071
• Make AsyncPredicate Sendable, constrain it to Sendable types #1072
• Update Require DSL to be (mostly) Sendable. #1130
• Make FailureMessage Sendable. #1131
• Make MatcherResult conform to Sendable #1132
• Make the Polling Helpers Sendable #1133
• Make AssertionHandler Sendable #1141

TODO

• Fix all the remaining concurrency warnings

[younata]

Now that we require Sendable closures when using async toEventually/async expressions, this presents an issue integrating with Quick.

In Quick, the common/promoted styling is to declare variables as vars in an ExampleGroup (i.e. describe, context, or even the root example group in the spec method). In Swift 5.9, when you pass a var to a sendable closure, you have to explicitly declare it. i.e.:

var subject: SomeClass!

// ...

it("does something") {
    expect { [subject] in await subject!.value }.to(...)
    // Note: In the closure, the type of `subject` is changed from a force-unwrap optional to a standard optional.
    // that is, the `!` boilerplate is now required.
}

Which is a terrible experience. It would be awfully nice if Swift would let us implicitly capture that var and pass it along.