Error 'isolated' parameter type 'Actor?' does not conform to 'Actor' or 'DistributedActor'

silvgabriel · April 9, 2025, 4:02pm

I'm having a strange experience using Testing framework in Xcode 16.3.

When I use @testable import iOS_AppName I'm getting the error below in the method and when I remove it the build works fine.


Showing All Errors Only
/var/folders/dr/xxmgy3xd1pb4ml_4c73_s78r0000gn/T/swift-generated-sources/@__swiftmacro_17iOS_AppNameTests7AppTestV8testName0F0fMp_.swift:3:90: 'any' has no effect on concrete type 'Actor'

/var/folders/dr/xxmgy3xd1pb4ml_4c73_s78r0000gn/T/swift-generated-sources/@__swiftmacro_17iOS_AppNameTests7AppTestV8testName0F0fMp_.swift:3:80: 'isolated' parameter type 'Actor?' does not conform to 'Actor' or 'DistributedActor'

I can only run the tests with @testable import iOS_AppName by adding @MainActor or async to the method.

Also in Xcode 16.2 I have no problem.

My test code:

@testable import iOS_AppName
import Testing

class AppClass { // This class is in the app's target, I left it here just to make it visible
    var name = "Swift"
}

struct AppTest {

    @Test
    func testName() {
        let appClass = AppClass()

        #expect(appClass.name == "Swift")
    }
}

Does anyone know if there is any configuration in the project that I can do to solve this?
This error is very strange and I would like your opinion before I add async to all the tests.

smontgomery · April 9, 2025, 4:10pm

Do you have a type in your app module named Actor? I can't seem to reproduce this in a small example project, perhaps because something in your app module (not shown in this snippet) is causing the error.

smontgomery · April 9, 2025, 4:12pm

Oh, I think I see the issue in Swift Testing's code. Can you please file a GitHub issue in the swift-testing repo?

silvgabriel · April 9, 2025, 4:24pm

lol you did it!

There was a class named Actor in the application, I updated it and now I can run the test build

Maybe some change added to the 6.1 testing framework conflicted this.
I spent half my work day yesterday trying to figure it out

Thank you @smontgomery!

smontgomery · April 9, 2025, 4:25pm

I’m working on a bug fix in swift-testing for this. It should be possible to have a type with that name in your own code, if you wish.

smontgomery · April 9, 2025, 5:24pm

Here's the fix:

github.com/swiftlang/swift-testing

Fully-qualify reference to Swift's `Actor` protocol in macro expansion code for synchronous test functions

main ← stmontgomery:actor-disambiguation

opened 05:24PM - 09 Apr 25 UTC

stmontgomery

+6 -1

This fixes a compilation error in code expanded from the `@Test` macro when it's… attached to a synchronous (i.e. non-`async`) test function in a context where there is a concrete type named `Actor`. For example, the following code reproduces the error: ```swift // In MyApp public class Actor {} // In test code import Testing import MyApp // ❌ 'any' has no effect on concrete type 'Actor' // - 'isolated' parameter type 'Actor?' does not conform to 'Actor' or 'DistributedActor' @Test func example() /* No 'async' */ {} ``` The macro code includes an unqualified reference to a type by that name, but it's intended to refer to the protocol in Swift's `_Concurrency` module. The fix is to ensure the macro's reference to this protocol is fully-qualified with a module name. This was first reported on the Swift Forums in https://forums.swift.org/t/error-isolated-parameter-type-actor-does-not-conform-to-actor-or-distributedactor/79190. This bug was introduced in #747, which first landed in Swift 6.1 and Xcode 16.3. ### Checklist: - [x] Code and documentation should follow the style of the [Style Guide](https://github.com/apple/swift-testing/blob/main/Documentation/StyleGuide.md). - [x] If public symbols are renamed or modified, DocC references should be updated.