It's possible that you're asking how to access application state from a UI test, or just in general UI testing.
I think it's a pretty interesting question so I'm going to answer because it's something that I don't know a lot about and hopefully will prompt other people to chime in and correct.
Background: A basic Magic 8 Ball project
I set up a basic project with a view controller that contains two views: a label and a button. Tapping the button updates the label text with a random message:
import UIKit
struct EightBall {
static let messages = ["Yes", "No", "It's not certain"]
var newMessage: String {
let randomIndex = Int(arc4random_uniform(UInt32(EightBall.messages.count)))
return EightBall.messages[randomIndex]
}
}
class ViewController: UIViewController {
let ball = EightBall()
@IBOutlet weak var messageLabel: UILabel!
@IBAction func shakeBall(_ sender: Any) {
messageLabel.text = ball.newMessage
}
}
A basic UI test
Here's a commented UI test showing how to automate tapping on the button, and grabbing the value of the label, and then checking that the value of the label is a valid message.
import XCTest
class MagicUITests: XCTestCase {
// This method is called before the invocation of each test method in the class.
override func setUp() {
super.setUp()
// In UI tests it is usually best to stop immediately when a failure occurs.
continueAfterFailure = true
// UI tests must launch the application that they test. Doing this in setup will make sure it happens for each test method.
XCUIApplication().launch()
}
func testValidMessage() {
// Grab reference to the application
let app = XCUIApplication()
// #1
// Grab reference to the label with the accesability identifier 'MessageLabel'
let messagelabelStaticText = app.staticTexts["MessageLabel"]
// Tap the button with the text 'Shake'
app.buttons["Shake"].tap()
// get the text of the label
let messageLabelText = messagelabelStaticText.label
// #2
// check if the text in the label matches one of the allowed messages
let isValidMessage = EightBall.messages.contains(messageLabelText)
// test will fail if the message is not valid
XCTAssert(isValidMessage)
}
}
At #1 The approach that I'm using to get the label is to access the labels accessibilityIdentifier property. For this project I entered this through storyboard, but if you're setting your views up in code you can directly set the accessibilityIdentifier property yourself.
The other thing that's confusing here is that to get access to elements in the view you're not navigating the view hierarchy, but a proxy of the hierarchy, which is why the syntax to get a label is the odd 'staticTexts' (The references at the bottom of the post explain this in more detail).
For #2 I'm inspecting the structure defined in my project. In a unit test you could access this my importing @testable import ProjectName but unfortunately this approach doesn't work for UI Test.
Instead, you'll have to make sure that any source file you want to access from the UI test is included as a target. You can do this in Xcode from this panel by checking the name of your UI test:
More UI testing references:
