Cannot override a specific dependancy using a preview trait

[wtpalexander]

I'm using a repository & protocol via dependencies. I'm wanting to override the dependancy to use a specific mocked version in my preview rather than the previewValue. Can anyone spot what I'm missing as it's currently just using the previewValue rather than what I suppose in the dependency preview trait?

protocol FooRepositoryProtocol { ... }

final class FooRepository: FooRepositoryProtocol { ... }

private enum FooRepositoryKey: DependencyKey, TestDependencyKey {
    static let liveValue: FooRepositoryProtocol = FooRepository()
    static let previewValue: FooRepositoryProtocol = MockFooRepository()
}

extension DependencyValues {
    var fooRepository: FooRepositoryProtocol {
        get { self[FooRepositoryKey.self] }
        set { self[FooRepositoryKey.self] = newValue }
    }
}

@available(iOS 18, *)
#Preview(traits: .dependency(\.fooRepository, .mock)) {
    NavigationStack {
        SearchForFriendsView()
    }
}

private extension FooRepositoryProtocol where Self == MockFooRepository {
    static var mock: MockFooRepository { MockFooRepository() }
}

Appreciate any thoughts!

[mbrandonw]

Hi @wtpalexander, is it possible to provide a compiling, self-contained example of the behavior you are seeing? I'm not seeing this when I try it out. Here's an example of overriding a depending in the preview:

And this is what happens when I do not override the dependency:

[wtpalexander]

Thanks @mbrandonw - really appreciate the quick response. Was just creating a minimum reproducible example (which I should have done first - apologies) and also see it working as expected. There must be something in my wider set up that is causing the issue. I'll look into it further there. Thanks again!