0-README.md

UX Testing with Rx

Sample iOS code that accompanies this blog post: https://brent.is/writing/nysc-tests

1-Test.swift

@testable import App
import KIF
import SwiftDate

class ExampleTest: KIFTestCase {

  func testClassReservation() {

    // ...login, etc.

    let tooLateToReserve = klass.reservationsEndAt + 15.minutes
    timeTravel(to: tooLateToReserve)

    // ...verify time-sensitive view state using KIF

  }

}

2-TestHelper.swift

protocol TimeTravel {}

extension XCTestCase: TimeTravel {

  func timeTravel(to time: NSDate) {
    NotificationCenter.post(.TimeTravel, ["to": time])
  }

}

3-NotificationCenter.swift

import RxSwift

class NotificationCenter {

  enum NotificationType: String {
    case TimeTravel
  }

  typealias NotificationInfo = [NSObject: AnyObject]?

  class func post(type: NotificationType, _ info: NotificationInfo = [:]) {
    NSNotificationCenter.defaultCenter()
      .postNotificationName(type.rawValue, object: nil, userInfo: info)
  }

  class func observe(type: NotificationType) -> Observable<NSNotification> {
    return
      NSNotificationCenter.defaultCenter()
        .rx_notification(type.rawValue)
  }

}

class NotificationClosureWrapper<T>: AnyObject {

  let closure: T

  init(closure: T) {
    self.closure = closure
  }

}

4-Time.swift

import RxSwift
import SwiftDate

struct Time {

  static var time$: Observable<NSDate> {
    let mutableTime$: Observable<NSDate> =
      NotificationCenter.observe(.TimeTravel)
        .map({ note -> NSDate? in
          let to: NSDate? = note.userInfo?["to"] as? NSDate
          return to
        })
        .filterNil()

    let systemTime$ =
      Observable<Int>.interval(1.minute, scheduler: MainScheduler.instance)
        .map { _ in NSDate() }
        .startWith(NSDate())

    let overridableTime$ =
      systemTime$
        .takeUntil(mutableTime$)

    let time$ =
      [mutableTime$, overridableTime$]
        .toObservable()
        .merge()
        .shareReplayLatestWhileConnected()

    return time$
  }

}

5-AppDelegate.swift

class AppDelegate: UIResponder, UIApplicationDelegate {

  func application(
    application: UIApplication,
    didFinishLaunchingWithOptions
    launchOptions: [NSObject: AnyObject]?) -> Bool {

    let time$ = Time.time$

    let vc = ExampleKlassViewController(time$: time$)

    self.window = UIWindow(frame: UIScreen.mainScreen().bounds)
    self.window?.rootViewController = vc
    self.window?.makeKeyAndVisible()

    return true
  }

}

5-ExampleKlassViewController.swift

class KlassDetailViewController: UIViewController {

  let klass: Klass
  let time$: Observable<NSDate>

  init(time$: Observable<NSDate>) {
    self.time$ = time$
    super.init(nibName: nil, bundle: nil)
  }

  override func viewDidLoad() {
    super.viewDidLoad()
    guard let view = self.view as? KlassDetailView else { return }

    let klass = // ...
    let klassDeadline$ = klass.reservationsEndAt$

    Observable
      .combineLatest(klassDeadline$, time$) { ($0, $1) }
      .subscribeNext { [unowned self] (deadline, time) in
        view.render(deadline, time)
      }
      .addDisposableTo(rx_disposeBag)
  }

}