It may seem easy to record UI tests, but there are challenges associated with getting them to run consistently. It is difficult to create and maintain a suite of UI tests that grow with your app. We'll explore different approaches to adding UI tests and find a balanced compromise that doesn't bog down a project too much.

1. Striking a Balance with UI Tests
By: Jesse Black
Software Engineer
stable|kernel
jesse.black@stablekernel.com

2. @stablekernel
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

3. 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.

4. Striking a Balance with UI Tests
@stablekernel
Overview
• General Testing
• Demo: Introducing UI Tests
• Improving UI Tests with Robots
• Mocking Dependencies
• Discussion

5. Types of Tests
@stablekernel
• Manual testing
• Automated testing
• Unit / Integrated / End to End
• Continuous Testing

6. Unit Tests
@stablekernel
• Tests a small amount of code with limited inputs and output
• Should be F.I.R.S.T.
• Fast
• Isolated
• Repeatable
• Self - Verifying
• Timely

7. Why test?
@stablekernel
• Fast feedback
• Help prevent regressions
• Improve code design

8. Demo
@stablekernel
UI Test Recording and Playback

9. Recording observations
@stablekernel
• Black box
• User’s perspective
• No Asserts (Assertion by tapping)

10. Example: Login Error
@stablekernel
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()

11. Example: Login Error
@stablekernel
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

12. Wrangle user facing strings
@stablekernel
• 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

13. Wrangle user facing string
@stablekernel
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: "")
}
}

14. Factor out user actions into Robots
@stablekernel
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)
}
}

15. Example: Login Error Refactored
@stablekernel
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())
}

16. Dependencies
@stablekernel
• Data persistence
• Networks
• Third Party Libraries

17. Mock Out Dependencies
@stablekernel

18. Mock Example: Login Credentials
@stablekernel
// UI Test Setup
override func setUp() {
super.setUp()
// ...
XCUIApplication().launchArguments = [“USE_MOCK_LOGIN_STORE”, “HAS_SAVED_USERNAME”]
XCUIApplication().launch()
}

19. Mock Example: Login Credentials
@stablekernel
protocol LoginCredentialsStore: class {
func saveUsername(username: String?)
func readUsername() -> String?
}

20. Mock Example: Login Credentials
@stablekernel
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
}
}

21. Realistic Goals
@stablekernel
• 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

22. Final Remarks
@stablekernel

23. Questions?
Business Inquiries:
Sarah Woodward
Director of Business Development
sarah.woodward@stablekernel.com
Jesse Black
Software Engineer
jesse.black@stablekernel.com
blog.stablekernel.com
@JesseBlack82