Navigator unit test

ContinueOnboardingFlowViewModelTests.swift

@MainActor
struct ContinueOnboardingFlowViewModelTests {
    let services: Services
    let testCoreDataStack: TestCoreDataStack

    var managedObjectContext: NSManagedObjectContext {
        testCoreDataStack.persistentContainer.viewContext
    }

    init() {
        self.services = .mock
        self.testCoreDataStack = TestCoreDataStack()
    }

    @Test
    func happyPath() async throws {
        let navigator = InspectableNavigator().typed(
            to: ContinueOnboardingFlowViewModel.NavigationDestination.self
        )
        let viewModel = ContinueOnboardingFlowViewModel(
            email: "[email protected]",
            services: services,
            premiumManager: PremiumManagerMock(),
            trackEvent: { _ in },
            managedObjectContext: managedObjectContext,
            navigator: navigator
        )

        viewModel.continueOnboardingViewModel.didPressContinue()

        let setPasswordViewModel = try #require(navigator.lastItem(\.setPassword))
        #expect(setPasswordViewModel.input == .enterPassword)
        setPasswordViewModel.onComplete(.passwordEntered(password: "hejhopp123"))

        let setPasswordViewModel2 = try #require(navigator.lastItem(\.setPassword))
        #expect(setPasswordViewModel2.input == .confirmPassword(password: "hejhopp123"))
        setPasswordViewModel2.onComplete(.passwordSet)

        let setupNotificationsViewModel = try #require(navigator.lastItem(\.setupNotifications))
        setupNotificationsViewModel.didFinish(.notificationsEnabled)

        #expect(navigator.lastItem.is(\.success))
    }
}

/// A navigator that allows inspection of the navigation path for testing purposes.
class InspectableNavigator: Navigator {
    var inspectableNavigationPath = [any Hashable]()

    override func push<T: Hashable>(_ value: T) {
        super.push(value)
        inspectableNavigationPath.append(value)
    }

    override func pop() {
        super.pop()
        inspectableNavigationPath.removeLast()
    }

    override func popToRoot() {
        super.popToRoot()
        inspectableNavigationPath.removeAll()
    }

    func typed<Destination: CasePathable>(
        to: Destination.Type
    ) -> TypedInspectableNavigator<Destination> {
        TypedInspectableNavigator<Destination>(navigator: self)
    }
}

/// A typed navigator that allows inspection of the navigation path for testing purposes.
/// It won't interfere with pushing or popping items, but it will allow you to retrieve the last item of a specific type.
class TypedInspectableNavigator<Destination: CasePathable & Hashable>: Navigator {
    private let navigator: InspectableNavigator

    init(navigator: InspectableNavigator) {
        self.navigator = navigator
    }

    override func push<T: Hashable>(_ value: T) {
        navigator.push(value)
    }

    override func pop() {
        navigator.pop()
    }

    override func popToRoot() {
        navigator.popToRoot()
    }

    var lastItem: Destination? {
        navigator.inspectableNavigationPath.last as? Destination
    }

    func lastItem<Value>(
        _ casePath: CaseKeyPath<Destination, Value>
    ) -> Value? {
        lastItem?[case: casePath]
    }
}