Testing View Controllers in Swift 3.0

Testing View Controllers in Swift 3.0

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Controller.swift

import UIKit

protocol Controller: class {
    var navigationController: NavigationController? { get }

    func present(wrappedController controller: Controller, animated flag: Bool, completion: Completion?)
    func present(controller: Controller, animated flag: Bool, completion: Completion?)
    func dismissController(animated flag: Bool, completion: Completion?)
}

extension Controller where Self: UIViewController {
    func present(wrappedController controller: Controller, animated flag: Bool, completion: Completion?) {
        guard let controller = controller as? UIViewController else { return }
        let navigationController = UINavigationController(rootViewController: controller)
        present(navigationController, animated: flag, completion: completion)
    }

    func present(controller: Controller, animated flag: Bool, completion: Completion?) {
        guard let controller = controller as? UIViewController else { return }
        present(controller, animated: flag, completion: completion)
    }

    func dismissController(animated flag: Bool = true, completion: Completion? = nil) {
        dismiss(animated: flag, completion: completion)
    }
}

extension UIViewController: Controller {
    var navigationController: NavigationController? { return navigationController }
}

protocol NavigationController {
    func pushViewController(_ viewController: UIViewController, animated: Bool)
    func popViewController(animated: Bool) -> UIViewController?
}

extension UINavigationController: NavigationController { }

MockController.swift

import UIKit
@testable import HostApp

class MockController: Controller {
    var navigationController: NavigationController? { return mockedNavigationController }
    var mockedNavigationController = MockNavigationController()

    private(set) var lastPresentedError: Error?
    private(set) var lastPresentedWrappedController: Controller?
    private(set) var lastPresentedController: Controller?
    private(set) var dismissControllerWasCalled = false

    func presentAlert(error: Error) {
        lastPresentedError = error
    }

    func present(wrappedController controller: Controller, animated flag: Bool, completion: Completion?) {
        lastPresentedWrappedController = controller
        completion?()
    }

    func present(controller: Controller, animated flag: Bool, completion: Completion?) {
        lastPresentedController = controller
        completion?()
    }

    func dismissController(animated flag: Bool, completion: Completion?) {
        dismissControllerWasCalled = true
        completion?()
    }
}

class MockNavigationController: NavigationController {
    private(set) var lastPushedViewController: UIViewController?
    private(set) var popViewControllerWasCalled = false

    func pushViewController(_ viewController: UIViewController, animated: Bool) {
        self.lastPushedViewController = viewController
    }

    func popViewController(animated: Bool) -> UIViewController? {
        popViewControllerWasCalled = true
        return nil
    }
}