SwiftUINavigation Test Case

ContentView.swift

import SwiftUI
import SwiftUINavigation
import XCTestDynamicOverlay

// MARK: - Screen One

@MainActor class ScreenOne: ObservableObject {
    @CasePathable
    @dynamicMemberLookup
    enum Destination {
        case two(ScreenTwo)
    }

    @Published var destination: Destination? {
        didSet {
            destination?.two?.onBack = {
                [weak self] in self?.destination = nil
            }
        }
    }
}

struct ScreenOneView: View {
    @ObservedObject var model: ScreenOne

    var body: some View {
        List {
            Button("Show Screen Two") {
                model.destination = .two(ScreenTwo())
            }
        }
        .navigationTitle("Screen One")
        .navigationDestination(
            unwrapping: $model.destination.two,
            destination: { $model in ScreenTwoView(model: model) }
        )
    }
}

// MARK: - Screen Two

@MainActor class ScreenTwo: ObservableObject {
    @CasePathable
    @dynamicMemberLookup
    enum Destination {
        case three(ScreenThree)
    }

    @Published var destination: Destination? {
        didSet {
            destination?.three?.onBack = {
                [weak self] in self?.destination = nil
            }
        }
    }

    var onBack: () -> Void = unimplemented()
}

struct ScreenTwoView: View {
    @ObservedObject var model: ScreenTwo

    var body: some View {
        List {
            Button("Show Screen Three") {
                model.destination = .three(ScreenThree())
            }

            Button("Go Back") {
                model.onBack()
            }
        }
        .navigationTitle("Screen Two")
        .navigationDestination(
            unwrapping: $model.destination.three,
            destination: { $model in ScreenThreeView(model: model) }
        )
    }
}

// MARK: - Screen Three

@MainActor class ScreenThree: ObservableObject {
    var onBack: () -> Void = unimplemented()
}

struct ScreenThreeView: View {
    @ObservedObject var model: ScreenThree

    var body: some View {
        List {
            Button("Go Back") {
                model.onBack()
            }
        }
        .navigationTitle("Screen Three")
    }
}

// MARK: - Previews

#Preview {
    ScreenOneView(model: ScreenOne())
}