guide_watchOS.md

View Hosting on watchOS

Because of WatchKit API limitations ViewInspector currently cannot automatically host your views for asynchronous tests - you need to add this swift file to your watchOS app target (for projects created prior Xcode 14 - to watchOS extension target).

Then, add the appropriate code snippet, depending on your setup:

If your watchOS project is using @main

1. Make sure to add WKExtensionDelegate and reference it in the App using @WKExtensionDelegateAdaptor.
2. Add let testViewSubject = TestViewSubject([]) as an instance variable to the ExtensionDelegate.
3. Add .testable(extDelegate.testViewSubject) to your ContentView inside WindowGroup.

The final code should look similar to this:

final class ExtensionDelegate: NSObject, WKExtensionDelegate {
    let testViewSubject = TestViewSubject([]) // #2
}

@main
struct MyWatchOSApp: App {
    
    @WKExtensionDelegateAdaptor(ExtensionDelegate.self) var extDelegate // #1
    
    var body: some Scene {
        WindowGroup {
            ContentView()
                .testable(extDelegate.testViewSubject) // #3
        }
    }
}

If your watchOS project is using storyboard

1. Make sure your root interface controller is a WKHostingController descendant.
2. Add let testViewSubject = TestViewSubject([]) as an instance variable to your root interface controller.
3. Add .testable(testViewSubject) to your ContentView
4. Replace var body: ContentView with var body: RootView<ContentView>
5. Replace WKHostingController<ContentView> with WKHostingController<RootView<ContentView>>

The final code should look similar to this:

final class RootInterfaceController: WKHostingController<RootView<ContentView>> { // #1 , #5
    
    let testViewSubject = TestViewSubject([]) // #2
    
    override var body: RootView<ContentView> { // #4
        return ContentView()
            .testable(testViewSubject) // #3
    }
}

struct ContentView: View {
    var body: some View {
        Text("Hi")
    }
}

Consequences of intruding the main build target's code

The proposed code snippets are using conditional compilation to minimize the footprint in the main build target.

The condition #if !(os(watchOS) && DEBUG) fully disintegrates the test code in Release builds and replaces it with these primitives:

typealias RootView<T> = T
typealias TestViewSubject = Set<Int>

extension View {
    @inline(__always)
    func testable(_ injector: TestViewSubject) -> Self {
        self
    }
}