Resetting NSUserDefaults in UI Testing

..md

Resetting NSUserDefaults in UI Testing

1. Add "UI-Testing" to launchArguments before launching the app under test
2. On launch, check for the argument in AppDelegate.swift
3. If it exists remove everything for the app's domain from NSUserDefaults

AppDelegate.swift

import UIKit

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
    var window: UIWindow?

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

        window = UIWindow(frame: UIScreen.mainScreen().bounds)
        window?.rootViewController = RootViewController()
        window?.makeKeyAndVisible()
        return true
    }

    private func resetStateIfUITesting() {
        if NSProcessInfo.processInfo().arguments.contains("UI-Testing") {
            NSUserDefaults.standardUserDefaults().removePersistentDomainForName(NSBundle.mainBundle().bundleIdentifier!)
        }
    }
}

UITests.swift

import XCTest

class UITests: XCTestCase {
    private let app = XCUIApplication()

    override func setUp() {
        super.setUp()
        app.launchArguments += ["UI-Testing"]
        app.launch()
    }
}

Genius. I actually took it one step further. I had a scenario for a first time user experience (which was tolled into the UserDefaults) and a whole test class with multiple test cases dedicated to it. The problem was, if you ran a test case you were no longer a new user.

I do have one "Tester" base type of class with a global setup and tear down which 99% of my tests will consume. But in this instance, I didn't want all my other tests to be treated as first time users. I wanted to delete the UserDefaults only for FTU. So in my FTU class, I simply did the same thing you did in your setup. To avoid having the launchArguments stored during my test run, I also overrode the tear down in my FTU class so that ever time that FTU test case was done, it removed the launch arguments. Hope this helps some poor schlub like me trying to figure out how to do this.

`class FTUTests: Tester {

override func setUp() {
    app.launchArguments += ["UI-Testing"]
    super.setUp()
}

override func tearDown() {
    app.launchArguments.removeAll()
    super.tearDown()
}

}`

For swift 4 resetStateIfUITesting will looks like:

private func resetStateIfUITesting() { if ProcessInfo.processInfo.arguments.contains("UI-Testing") { UserDefaults.standard.removePersistentDomain(forName: Bundle.main.bundleIdentifier!) } }

This doesn't work for me anymore (Xcode 9.3.1 atm).

If I print ProcessInfo.processInfo.arguments at application start, any arguments set like app.launchArguments += ["UI-Testing"] aren't set in there.

Works great in Xcode 10!