UI Testing

Running Tests

xcodebuild test \
  -project Telegram/Telegram.xcodeproj \
  -scheme iOSAppUITestSuite \
  -destination 'platform=iOS Simulator,name=iPhone 17,OS=26.1'

Pick any available simulator. List them with xcrun simctl list devices available iPhone.

Test Environment

Tests launch the app with the --ui-test argument. When the app detects this flag:

• It uses an isolated data directory (telegram-ui-tests-data/ inside the app group container), completely separate from production data.
• That directory is wiped on every launch, so each test run starts with a clean slate.
• The app connects to Telegram test servers (not production). Test server accounts are independent of production accounts.

This means every test begins with the app in its first-launch state: no accounts, no data, showing the welcome/auth screen.

Writing Tests

Test files live in Telegram/Tests/Sources/. The test target is iOSAppUITestSuite.

Tests use Apple's XCUITest framework. Each test class extends XCTestCase and interacts with the app through XCUIApplication.

Template

import XCTest

class MyFeatureTests: XCTestCase {
    private var app: XCUIApplication!

    override func setUpWithError() throws {
        continueAfterFailure = false
        app = XCUIApplication()
        app.launchArguments.append("--ui-test")
    }

    override func tearDownWithError() throws {
        app = nil
    }

    func testSomething() throws {
        app.launch()

        // Find elements
        let button = app.buttons["Start Messaging"]

        // Wait for elements to appear
        XCTAssert(button.waitForExistence(timeout: 5.0))

        // Interact
        button.tap()

        // Assert
        XCTAssert(app.textFields["Phone Number"].waitForExistence(timeout: 3.0))
    }
}

Key Patterns

Always pass --ui-test in launchArguments. Without it, the app uses production servers and the real database.

Wait for elements rather than assuming they exist immediately. Use element.waitForExistence(timeout:) before interacting.

Find elements by accessibility identifier, label, or type:

app.buttons["Continue"]           // by label
app.textFields["Phone Number"]    // by placeholder/label
app.staticTexts["Welcome"]        // static text
app.navigationBars["Settings"]    // navigation bar

Relaunch between tests if needed. Each app.launch() call with --ui-test wipes the database, so every test method that calls launch() gets a fresh app state.

Type text into fields:

let field = app.textFields["Phone Number"]
field.tap()
field.typeText("9996621234")

Adding a New Test File

1. Create a new .swift file in Telegram/Tests/Sources/.
2. The file is automatically picked up by the iOSAppUITestSuite target via the Bazel build — no manual target membership changes needed.
3. Run with the same xcodebuild test command.

Telegram Test Servers

The test environment uses 3 separate Telegram datacenters, completely independent from production.

OS Environment

Test logins are guarded behind a specialized OS environment. The simulator or device must be configured for the test environment before test accounts can authenticate.

Test Phone Numbers

Test phone numbers follow the format 99966XYYYY:

• X is the DC number (1, 2, or 3)
• YYYY are random digits

The country code for test numbers is 999, and the remaining digits are 66XYYYY.

Examples: +999 66 2 1234, +999 66 1 0000, +999 66 3 0001.

Verification Codes

Test accounts do not receive real SMS. The confirmation code is the DC number repeated 5 times:

• DC 1 (+999 661 YYYY) -> code 11111
• DC 2 (+999 662 YYYY) -> code 22222
• DC 3 (+999 663 YYYY) -> code 33333

Flood Limits

Test numbers are still subject to flood limits. If a number gets rate-limited, pick a different YYYY suffix.

Deleting Test Accounts

Tests that exercise the sign-up flow create an account on the test servers. Re-running the same test with the same phone number will skip sign-up because the account already exists. To get a fresh sign-up screen, delete the account before running the test.

The app supports a --delete-test-account <phone> launch argument. When combined with --ui-test, the app logs into the test account, deletes it, and exits — no UI is shown. The verification code is derived automatically from the phone number (DC digit repeated 5 times).

In UI tests, use this by launching a separate app instance:

private func deleteTestAccount(phone: String) {
    let cleanupApp = XCUIApplication()
    cleanupApp.launchArguments += ["--ui-test", "--delete-test-account", phone]
    cleanupApp.launch()
    let terminated = cleanupApp.wait(for: .notRunning, timeout: 30)
    XCTAssert(terminated, "test account cleanup did not complete in 30s")
}

Call deleteTestAccount(phone:) at the start of any test that needs a clean sign-up flow. The phone number format is 99966XYYYY (no + prefix needed).

Security

Do not store any important or private information in test accounts. Anyone can use the simplified authorization mechanism to access them.