Striking a Balance with UI TestsBy: Jesse BlackSoftware Engineerstable|kernel jesse.black@stablekernel.com

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Hi, I’m Jesse Black.

• Programming for over nine years• Created a Mac App for my family business• Worked for 3 years with Gramercy Consultants developing iOS and Android apps• Working for stable|kernel for the past 4 years developing iOS apps, Android apps

and their supporting APIs

We’re stable|kernel. stable|kernel is an Atlanta-based mobile development company to craft smartly-designed mobile applications that connect brands directly with their users.

Striking a Balance with UI Tests

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Overview

• General Testing• Demo: Introducing UI Tests• Improving UI Tests with Robots• Mocking Dependencies• Discussion

Types of Tests

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• Manual testing• Automated testing• Unit / Integrated / End to End

• Continuous Testing

Unit Tests

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• Tests a small amount of code with limited inputs and output• Should be F.I.R.S.T.

• Fast• Isolated• Repeatable• Self - Verifying• Timely

Why test?

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• Fast feedback• Help prevent regressions• Improve code design

Demo

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UI Test Recording and Playback

Recording observations

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• Black box• User’s perspective• No Asserts (Assertion by tapping)

Example: Login Error

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let app = XCUIApplication()let usernameTextField = app.textFields["Username"]usernameTextField.tap()usernameTextField.typeText("invalid")app.children(matching: .window).element(boundBy: 0).children(matching: .other).element.children(matching: .other).element(boundBy: 0).tap() let passwordSecureTextField = app.secureTextFields["Password"]passwordSecureTextField.tap()passwordSecureTextField.typeText("invalid")app.children(matching: .window).element(boundBy: 0).children(matching: .other).element.children(matching: .other).element(boundBy: 0).tap()app.buttons[“Login"].tap() app.alerts["Username and password combo not found."].buttons["OK"].tap()

Example: Login Error

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let app = XCUIApplication()let usernameTextField = app.textFields["Username"]usernameTextField.tap()usernameTextField.typeText("invalid")app.children(matching: .window).element(boundBy: 0).children(matching: .other).element.children(matching: .other).element(boundBy: 0).tap() let passwordSecureTextField = app.secureTextFields["Password"]passwordSecureTextField.tap()passwordSecureTextField.typeText("invalid")app.children(matching: .window).element(boundBy: 0).children(matching: .other).element.children(matching: .other).element(boundBy: 0).tap()app.buttons[“Login"].tap() app.alerts["Username and password combo not found."].buttons["OK"].tap()

• Scary strings• Will fail without network• Chunks of very similar code• Fragile tap to dismiss lines

Wrangle user facing strings

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• Localize all user facing strings• Add localized string file to both targets; app and UI Test targets• Create abstraction around NSLocalizedString to avoid using stringly

typed keys when accessing user facing strings

Wrangle user facing string

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enum UIString: String { case usernamePlaceholder = "username-placeholder"

func localized() -> String { return UIStringsHelper.getLocalizedString(key: rawValue) }}

private class UIStringsHelper { static func getLocalizedString(key: String) -> String { let bundle = Bundle(for: UIStringsHelper.self) return NSLocalizedString(key, bundle: bundle, comment: "") }}

Factor out user actions into Robots

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struct LoginRobot { let app: XCUIApplication

var usernameTextField: XCUIElement { return app.textFields[UIString.usernamePlaceholder.localized()] }

func dismissKeyboard() { app.children(matching: .window).element(boundBy: 0).children(matching: .other).element.children(matching: .other).element(boundBy: 0).tap() }

func enterUsername(text: String) { usernameTextField.tap() usernameTextField.typeText(text) }

}

Example: Login Error Refactored

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func testInvalidCredentials() {loginRobot.enterUsername(text: "invalid@email")loginRobot.dismissKeyboard()

loginRobot.enterPassword(text: "invalid")loginRobot.dismissKeyboard()

loginRobot.loginButton.tap()

let alertRobot = AlertRobot(app: XCUIApplication(), title: "Username and password combo not found.")alertRobot.dismiss(withButtonTitled: UIString.okButton.localized())

}

Dependencies

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• Data persistence• Networks• Third Party Libraries

Mock Out Dependencies

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Mock Example: Login Credentials

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// UI Test Setupoverride func setUp() { super.setUp()

// ...

XCUIApplication().launchArguments = [“USE_MOCK_LOGIN_STORE”, “HAS_SAVED_USERNAME”] XCUIApplication().launch()}

Mock Example: Login Credentials

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protocol LoginCredentialsStore: class { func saveUsername(username: String?) func readUsername() -> String?}

Mock Example: Login Credentials

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class MockLoginCredentialsStore: LoginCredentialsStore {

var savedUsername: String?

init() { if CommandLine.arguments.contains("HAS_SAVED_USERNAME") { savedUsername = "jesse.black@stablekernel.com" } }

func saveUsername(username: String?) { savedUsername = username }

func readUsername() -> String? { return savedUsername }}

Realistic Goals

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• Automate screen shots of your app as you roll out changes• Be prepared for demos with stakeholders as you close out units of work

• Increase confident that previously demoed work does not have any regressions

Final Remarks

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Questions?

Business Inquiries:Sarah WoodwardDirector of Business Developmentsarah.woodward@stablekernel.com

Jesse BlackSoftware Engineerjesse.black@stablekernel.comblog.stablekernel.com@JesseBlack82