Teknasyon-Teknoloji / AccessibilityIdentificable

Identifiers for UI testing: a reflection based approach

AccessibilityIdentificable

Identifiers for UI testing: a reflection based approach

One of the most annoying things about UI Testing in iOS is the need to assign Accessibility Identifiers to views that are hard to access otherwise.

What if we could generate and assign Accessibility Identifiers automatically?

Usually, assigning an Accessibility Identifier to a View is rather straightforward and it is creating a lot of boilerplate code…

override func viewDidLoad() {
    titleLabel.accessibilityIdentifier          = "SomethingViewController.titleLabel"
    descriptionLabel.accessibilityIdentifier    = "SomethingViewController.descriptionLabel"
    doneButton.accessibilityIdentifier          = "SomethingViewController.doneButton"
}

I was searching for some solution but they were not fully satisfy me, but i used them to create this one. I have used Swift’s reflection API: Mirror with Objective-C swizzling technique and everything is completed by the code generator Sourcery to have direct reference from UITests.

@objc public protocol AccessibilityIdentificable { /* NOOP */ }

public extension AccessibilityIdentificable {

    func generateAccessibilityIdentifiers() {
        let mirror = Mirror(reflecting: self)

        for child in mirror.children {
            guard let identifier = child.label?.replacingOccurrences(of: ".storage", with: "")
                    .replacingOccurrences(of: "$__lazy_storage_$_", with: "") else {
                continue
            }

            if let view = child.value as? UIView {
                view.accessibilityIdentifier = "\(type(of: self)).\(identifier)"

            } else if let array = child.value as? [UIView] {
                for (index, object) in array.enumerated() {
                    object.accessibilityIdentifier = "\(type(of: self)).\(identifier)_\(index)"
                }
            }
        }
    }
}

Usage is straightforward, all properties from classes that implements AccessibilityIdentificable protocol will have generated accessibility identifiers. Just implement AccessibilityIdentificable to UIViewController or custom object and add AccessibilityInjector.inject() line for swizzling UIViewController viewDidLoad, init(frame:) and init(coder:) of UIView. We need that to call automatically generateAccessibilityIdentifiers from AccessibilityIdentificable after these methods and assign accessibilityIdentifier to each UIView.

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
    // Override point for customization after application launch.

    if ProcessInfo.processInfo.arguments.contains("-xcuitest") {
        AccessibilityInjector.inject()
    }
    return true
}

class CustomView: UIView, AccessibilityIdentificable {
    private var label: UILabel = UILabel(frame: .zero) #--> will set accessibilityIdentifier: CustomView.label
}

To be able to find and generate all classes that implements AccessibilityIdentificable you need to add Build Phases -> Run Script which will change depends on project structure and for me look like this:

#/bin/sh

$PODS_ROOT/Sourcery/bin/sourcery --sources $SRCROOT --sources $SRCROOT/../Source --output $SRCROOT/AccessibilityIdentificableUITests/Generated --templates $SRCROOT/../Template

Sourcery in UITests will generate classes:

// @generated
// MARK: - Identifiers > CustomView

public extension Identifiers {
    struct CustomView {
        public static var label = "CustomView.label"
    }
}

Then inside UITests you can use this identifiers:

func testExample() throws {
    // UI tests must launch the application that they test.
    let app = XCUIApplication()
    app.launchArguments.append("-xcuitest")
    app.launch()

    XCTAssert(app.staticTexts[Identifiers.CustomView.label].exists)
}

In addition to that if you would like to add custom accessibility identifiers for some reasons, i prepared @propertyWrapper named @AccessibilityIdentify which you can use setting custom identifiers.

class ViewController: UIViewController {

    @AccessibilityIdentify(identifier: "custom_id")
    var testView = UIView()
}