Test failing?
├─ Element not found?
│  └─ Use waitForExistence(timeout:) not sleep()
├─ Passes locally, fails CI?
│  └─ Replace sleep() with condition polling
├─ Animation causing issues?
│  └─ Wait for animation completion, don't disable
└─ Network request timing?
   └─ Use XCTestExpectation or waitForExistence

func testButtonAppears() {
    app.buttons["Login"].tap()
    sleep(2)  // ❌ Guessing it takes 2 seconds
    XCTAssertTrue(app.buttons["Dashboard"].exists)
}

func testButtonAppears() {
    app.buttons["Login"].tap()
    let dashboard = app.buttons["Dashboard"]
    XCTAssertTrue(dashboard.waitForExistence(timeout: 5))
}

// Wait for element to appear
func waitForElement(_ element: XCUIElement, timeout: TimeInterval = 5) -> Bool {
    return element.waitForExistence(timeout: timeout)
}

// Usage
XCTAssertTrue(waitForElement(app.buttons["Submit"]))

func waitForElementToDisappear(_ element: XCUIElement, timeout: TimeInterval = 5) -> Bool {
    let predicate = NSPredicate(format: "exists == false")
    let expectation = XCTNSPredicateExpectation(predicate: predicate, object: element)
    let result = XCTWaiter().wait(for: [expectation], timeout: timeout)
    return result == .completed
}

// Usage
XCTAssertTrue(waitForElementToDisappear(app.activityIndicators["Loading"]))

func waitForButton(_ button: XCUIElement, toBeEnabled enabled: Bool, timeout: TimeInterval = 5) -> Bool {
    let predicate = NSPredicate(format: "isEnabled == %@", NSNumber(value: enabled))
    let expectation = XCTNSPredicateExpectation(predicate: predicate, object: button)
    let result = XCTWaiter().wait(for: [expectation], timeout: timeout)
    return result == .completed
}

// Usage
let submitButton = app.buttons["Submit"]
XCTAssertTrue(waitForButton(submitButton, toBeEnabled: true))
submitButton.tap()

Button("Submit") {
    // action
}
.accessibilityIdentifier("submitButton")

func testSubmitButton() {
    let submitButton = app.buttons["submitButton"]  // Uses identifier, not label
    XCTAssertTrue(submitButton.waitForExistence(timeout: 5))
    submitButton.tap()
}

func testDataLoads() {
    app.buttons["Refresh"].tap()

    // Wait for loading indicator to disappear
    let loadingIndicator = app.activityIndicators["Loading"]
    XCTAssertTrue(waitForElementToDisappear(loadingIndicator, timeout: 10))

    // Now verify data loaded
    XCTAssertTrue(app.cells.count > 0)
}

func testAnimatedTransition() {
    app.buttons["Next"].tap()

    // Wait for destination view to appear
    let destinationView = app.otherElements["DestinationView"]
    XCTAssertTrue(destinationView.waitForExistence(timeout: 2))

    // Optional: Wait a bit more for animation to settle
    // Only if absolutely necessary
    RunLoop.current.run(until: Date(timeIntervalSinceNow: 0.3))
}

func testExample() {
    let app = XCUIApplication()
    app.launchArguments = ["UI-Testing"]
    app.launch()
}

if ProcessInfo.processInfo.arguments.contains("UI-Testing") {
    // Use mock data, skip onboarding, etc.
}

override func setUpWithError() throws {
    continueAfterFailure = false  // Stop on first failure
}

func testExample() {
    // Take screenshot on failure
    addUIInterruptionMonitor(withDescription: "Alert") { alert in
        alert.buttons["OK"].tap()
        return true
    }

    // Print element hierarchy
    print(app.debugDescription)
}

sleep(5)  // ❌ Wastes time if operation completes in 1s

app.buttons["Next"].tap()
XCTAssertTrue(app.buttons["Back"].exists)  // ❌ May fail during animation

app.buttons["Submit"].tap()  // ❌ Breaks with localization

// ❌ Test 2 assumes Test 1 ran first
func test1_Login() { /* ... */ }
func test2_ViewDashboard() { /* assumes logged in */ }

element.waitForExistence(timeout: 100)  // ❌ Too long
element.waitForExistence(timeout: 0.1)  // ❌ Too short

Button("Submit") {
    // action
}
.accessibilityIdentifier("submitButton")

// Make identifiers specific to instance
List(landmarks) { landmark in
    LandmarkRow(landmark)
        .accessibilityIdentifier("landmark-\(landmark.id)")
}

let button = UIButton()
button.accessibilityIdentifier = "submitButton"

// Use index for table cells
cell.accessibilityIdentifier = "cell-\(indexPath.row)"

Prompt: "Add accessibility identifiers to the relevant parts of this view"

func testCreateAustralianCollection() {
    let app = XCUIApplication()
    app.launch()

    // Tap "Collections" tab (recorded automatically)
    app.tabBars.buttons["Collections"].tap()

    // Tap "+" to add new collection
    app.navigationBars.buttons["Add"].tap()

    // Tap "Edit" button
    app.buttons["Edit"].tap()

    // Type collection name
    app.textFields.firstMatch.tap()
    app.textFields.firstMatch.typeText("Max's Australian Adventure")

    // Tap "Edit Landmarks"
    app.buttons["Edit Landmarks"].tap()

    // Add landmarks
    app.tables.cells.containing(.staticText, identifier:"Great Barrier Reef").buttons["Add"].tap()
    app.tables.cells.containing(.staticText, identifier:"Uluru").buttons["Add"].tap()

    // Tap checkmark to save
    app.navigationBars.buttons["Done"].tap()
}

// Recorded options for text field:
app.textFields["Collection Name"]              // ❌ Breaks if label localizes
app.textFields["collectionNameField"]          // ✅ Uses identifier
app.textFields.element(boundBy: 0)             // ✅ Position-based
app.textFields.firstMatch                      // ✅ Generic, shortest

// Validate collection created
let collection = app.buttons["Max's Australian Adventure"]
XCTAssertTrue(collection.waitForExistence(timeout: 5))

// Wait for button to become enabled
let submitButton = app.buttons["Submit"]
XCTAssertTrue(submitButton.wait(for: .enabled, toEqual: true, timeout: 5))

// Fail test if element doesn't appear
let landmark = app.staticTexts["Great Barrier Reef"]
XCTAssertTrue(landmark.waitForExistence(timeout: 5), "Landmark should appear in collection")

override func setUpWithError() throws {
    let app = XCUIApplication()

    // Set device orientation
    XCUIDevice.shared.orientation = .landscapeLeft

    // Set appearance mode
    app.launchArguments += ["-UIUserInterfaceStyle", "dark"]

    // Simulate location
    let location = XCUILocation(location: CLLocation(latitude: 37.7749, longitude: -122.4194))
    app.launchArguments += ["-SimulatedLocation", location.description]

    app.launch()
}

func testWithMockData() {
    let app = XCUIApplication()

    // Pass arguments to app
    app.launchArguments = ["-UI-Testing", "-UseMockData"]

    // Set environment variables
    app.launchEnvironment = ["API_URL": "https://mock.api.com"]

    app.launch()
}

if ProcessInfo.processInfo.arguments.contains("-UI-Testing") {
    // Use mock data, skip onboarding
}

// Open app to specific URL
let app = XCUIApplication()
app.open(URL(string: "myapp://landmark/123")!)

// Open URL with system default app (global version)
XCUIApplication.open(URL(string: "https://example.com")!)

func testAccessibility() throws {
    let app = XCUIApplication()
    app.launch()

    // Perform accessibility audit
    try app.performAccessibilityAudit()
}

Configurations:
├─ English
├─ German (longer strings)
├─ Arabic (right-to-left)
└─ Hebrew (right-to-left)

// Test expected:
let button = app.buttons["Max's Australian Adventure"]

// But overlay shows it's actually text, not button:
let text = app.staticTexts["Max's Australian Adventure"] // ✅ Correct

# Check if installed
ls ~/Library/Application\ Support/Network\ Link\ Conditioner/

override func setUpWithError() throws {
    let app = XCUIApplication()

    // Launch with network conditioning argument
    app.launchArguments = ["-com.apple.CoreSimulator.CoreSimulatorService", "-networkShaping"]
    app.launch()
}

override func setUpWithError() throws {
    let app = XCUIApplication()

    // Simulate 3G (type in launch arguments)
    app.launchEnvironment = [
        "SIMULATOR_UDID": ProcessInfo.processInfo.environment["SIMULATOR_UDID"] ?? "",
        "NETWORK_PROFILE": "3G"
    ]
    app.launch()
}

func testPhotoUpload() {
    app.buttons["Upload Photo"].tap()

    // Passes locally (fast network)
    XCTAssertTrue(app.staticTexts["Upload complete"].waitForExistence(timeout: 5))
}
// ✅ Passes locally, ❌ FAILS on 3G with timeout

func testPhotoUploadOn3G() {
    let app = XCUIApplication()
    // Network Link Conditioner running (3G profile)
    app.launch()

    app.buttons["Upload Photo"].tap()

    // Increase timeout for 3G
    XCTAssertTrue(app.staticTexts["Upload complete"].waitForExistence(timeout: 30))

    // Verify no crash occurred
    XCTAssertFalse(app.alerts.element.exists, "App should not crash on 3G")
}

Configurations:
├─ iPhone 14 Pro + LTE
├─ iPhone 14 Pro + 3G
├─ iPad Pro 12.9 + LTE
├─ iPad Pro 12.9 + 3G  (⚠️ Most failures here)
└─ iPhone 12 + 3G      (⚠️ Older device)

import XCTest

final class MultiFactorUITests: XCTestCase {
    var deviceModel: String { UIDevice.current.model }

    override func setUpWithError() throws {
        let app = XCUIApplication()
        app.launch()

        // Adjust timeouts based on device
        switch deviceModel {
        case "iPad" where UIScreen.main.bounds.width > 1000:
            // iPad Pro - larger layout, slower rendering
            app.launchEnvironment["TEST_TIMEOUT"] = "30"
        case "iPhone":
            // iPhone - compact, standard timeout
            app.launchEnvironment["TEST_TIMEOUT"] = "10"
        default:
            app.launchEnvironment["TEST_TIMEOUT"] = "15"
        }
    }

    func testListLoadingAcrossDevices() {
        let app = XCUIApplication()
        let timeout = Double(app.launchEnvironment["TEST_TIMEOUT"] ?? "10") ?? 10

        app.buttons["Refresh"].tap()

        // Wait for list to load (timeout varies by device)
        XCTAssertTrue(
            app.tables.cells.count > 0,
            "List should load on \(deviceModel)"
        )

        // Verify no crashes
        XCTAssertFalse(app.alerts.element.exists)
    }
}

func testLargeLayoutOn3G() {
    let app = XCUIApplication()
    // Running with Network Link Conditioner on 3G profile
    app.launch()

    // iPad Pro: Large grid of images
    app.buttons["Browse"].tap()

    // Wait longer for images on slow network
    let firstImage = app.images["photoGrid-0"]
    XCTAssertTrue(
        firstImage.waitForExistence(timeout: 20),
        "First image must load on slow network"
    )

    // Verify grid loaded without crash
    let loadedCount = app.images.matching(identifier: NSPredicate(format: "identifier BEGINSWITH 'photoGrid'")).count
    XCTAssertGreater(loadedCount, 5, "Multiple images should load on 3G")

    // No alerts (no crashes)
    XCTAssertFalse(app.alerts.element.exists, "App should not crash on large device + slow network")
}

- name: Run tests across devices
  run: |
    xcodebuild -scheme MyApp \
      -testPlan MultiDeviceTestPlan \
      test

Failing test: testPhotoUpload
Error: The app crashed while responding to a UI event
App died from an uncaught exception
Stack trace: [EXC_BAD_ACCESS in PhotoViewController]

override func setUpWithError() throws {
    let app = XCUIApplication()

    // Enable all logging
    app.launchEnvironment = [
        "OS_ACTIVITY_MODE": "debug",
        "DYLD_PRINT_STATISTICS": "1"
    ]

    // Enable test diagnostics
    if #available(iOS 17, *) {
        let options = XCUIApplicationLaunchOptions()
        options.captureRawLogs = true
        app.launch(options)
    } else {
        app.launch()
    }
}

func testReproduceCrash() {
    let app = XCUIApplication()
    app.launch()

    // Run exact sequence that causes crash
    app.buttons["Browse"].tap()
    app.buttons["Photo Album"].tap()
    app.buttons["Select All"].tap()
    app.buttons["Upload"].tap()

    // Should crash here
    let uploadButton = app.buttons["Upload"]
    XCTAssertFalse(uploadButton.exists, "App crashed (expected)")

    // Don't assert - just let it crash and read logs
}

Exception Type: EXC_BAD_ACCESS (SIGSEGV)
Exception Codes: KERN_INVALID_ADDRESS at 0x0000000000000000
Thread 0 Crashed:
0  MyApp    0x0001a234 -[PhotoViewController reloadPhotos:] + 234
1  MyApp    0x0001a123 -[PhotoViewController viewDidLoad] + 180

// Common pattern: Race condition in async image loading
class PhotoViewController: UIViewController {
    var photos: [Photo] = []

    override func viewDidLoad() {
        super.viewDidLoad()

        // ❌ WRONG: Accessing photos array from multiple threads
        Task {
            let newPhotos = await fetchPhotos()
            self.photos = newPhotos  // May crash if main thread access
            reloadPhotos()  // ❌ Crash here
        }
    }
}

// ✅ CORRECT: Ensure main thread
class PhotoViewController: UIViewController {
    @MainActor
    var photos: [Photo] = []

    override func viewDidLoad() {
        super.viewDidLoad()

        Task {
            let newPhotos = await fetchPhotos()
            await MainActor.run { [weak self] in
                self?.photos = newPhotos
                self?.reloadPhotos()  // ✅ Safe
            }
        }
    }
}

func testPhotosLoadWithoutCrash() {
    let app = XCUIApplication()
    app.launch()

    // Rapid fire interactions that previously caused crash
    app.buttons["Browse"].tap()
    app.buttons["Photo Album"].tap()

    // Load should complete without crash
    let photoGrid = app.otherElements["photoGrid"]
    XCTAssertTrue(photoGrid.waitForExistence(timeout: 10))

    // No alerts (no crash dialogs)
    XCTAssertFalse(app.alerts.element.exists)
}

func testPhotosLoadUnderStress() {
    let app = XCUIApplication()
    app.launch()

    // Repeat the crash-causing action multiple times
    for iteration in 0..<10 {
        app.buttons["Browse"].tap()

        // Wait for load
        let grid = app.otherElements["photoGrid"]
        XCTAssertTrue(grid.waitForExistence(timeout: 10), "Iteration \(iteration)")

        // Go back
        app.navigationBars.buttons["Back"].tap()
        app.buttons["Refresh"].tap()
    }

    // Completed without crash
    XCTAssertTrue(true, "Stress test passed")
}