The Grass on the Other Side - iOS Testing Techniques

This is a talk at the Google Developer Group in Nuremberg summarizing iOS testing tools, frameworks and techniques for Android developers.

Transcript

1. The Grass on the Other Side iOS Testing Techniques 1
2. Agenda 1. Why I'm here 2. Unit & Integration Tests 3. UI Tests 4. Controlling Singletons 5. Snapshot Tests 2
3. About me • ! iOS developer since 2013, joined adorsys 2014 • In my free time I • " enjoy bouldering • # host a pub quiz • $ travel a lot • % Programming languages & developer tools • ❤ Swift is my favorite • ✅ Loooove green checkmarks in tests • ( Twitter: @xavierLowmiller 3
4. Why I'm here I like peeking over the fence. Different perspectives make my code better. I hope some of the stuff here makes sense to you. 4
5. The testing pyramid 5 https:/ /martinfowler.com/bliki/TestPyramid.html
6. Testing on iOS • Cocoa MVC is more than 20 years old • Not created with testing in mind • Xcode has really nice support for tests and reports • Testing in the Simulator has a ton of overhead • If you can get away with it, run your tests without a host app 6
7. Unit Tests • Fast as f*** • Cheap • You can never have enough of these • Small amounts of code coverage • White Box 7
9. func testUnionBetweenSetsShouldContainAllElements() { // Given let set1: Set<Int> = [1, 2] let set2: Set<Int> = [2, 3] // When let union = set1.union(set2) // Then XCTAssertEqual(union, [1, 2, 3]) } 9
10. Integration Tests • Are almost as fast • A little annoying • Esp. when working with views and windows • Medium amounts of code coverage • White Box 10
11. func testCancelingShouldShowHintViewControllerBeforeDismissing() { // Given let window = UIWindow() window.rootViewController = viewController window.makeKeyAndVisible() // When viewController.cancelButtonTapped() // Then let presented = viewController.presentedViewController as UINavigationController? XCTAssertNotNil(presented) let infoVC = presented ?.topViewController XCTAssert(infoVC is InfoAlertViewController) } 11
12. UI Tests • Sloooow • XCUITest was introduced in 2014 • Still a little buggy sometimes • Pretty cool tooling • Often used to implement E2E tests • Fantastic amounts of code coverage • Black Box 12
14. func testLoginWithUsernameAndPassword() { let app = XCUIApplication() app.buttons["Login"].tap() app.textFields["LOGIN_FIELD"].typeText("a@b.com") app.secureTextFields["PASSWORD_FIELD"].typeText("s3cret") XCTAssert(app.navigationBars.staticTexts["Logged in"].exists) } 14
15. Cool stuff you can do • Screenshots • Record Mode 15
16. Demo https:/ /github.com/spacepandas/cineaste-ios https:/ /github.com/spacepandas/cineaste-android 16
17. Tips • Skip all animations • UIView.setAnimationsEnabled(false) • UI Tests are built on Accessibility features • Have great Accessibility -> Have great UI Tests 17
18. Controlling Singletons 18
19. How do you test this? func showTodaysDate() -> String { let date = Date() return date.formatted() // ... } 19
20. How do you test this? func showTodaysDate() -> String { let date = Date() return date.formatted() // ... } func testShowTodaysDate() { XCAssertEqual(today, "April 11th, 2019") // This test will fail tomorrow ... } 20
21. struct World { var date: () -> Date = Date.init } var Current = World() 21
22. func showTodaysDate() -> String { let date = Current.date() return date.formatted() // ... } func testShowTodaysDate() { // Given Current.date = { Date(timeIntervalSince1970: 123456) } // When let today = showTodaysDate() // Then XCAssertEqual(today, "January 2nd, 1970") } 22
23. struct World { var date: () -> Date = Date.init } #if DEBUG var Current = World() #else let Current = World() #endif 23
24. Control the World! • Caches • Authentication • Analytics • Persistence • Locale & Calendars • Networking • Singletons 24
25. More on this • How To Control The World (Talk) Stephen Celis, NSSpain 2018 • How To Control The World (Blog Post) Stephen Celis & Brandon Williams, Pointfree.co 25
26. Snapshot Tests The new hotness ! 26
27. func testButtonConfiguration() { let button = UIButton.primaryButton XCTAssertEqual(button.backgroundColor, .green) XCTAssertEqual(button.title(for: .normal), "Primary Button") XCTAssertEqual(button.titleColor(for: .normal), .white) // ... } 27
28. func testButtonConfiguration() { let button = UIButton.primaryButton XCTAssertEqual(button.backgroundColor, .green) XCTAssertEqual(button.title(for: .normal), "Primary Button") XCTAssertEqual(button.titleColor(for: .normal), .white) // ... } This is boring and repetitive 28
29. import SnapshotTesting func testButtonConfiguration() { let button = UIButton.primaryButton assertSnapshot(matching: button, as: .image) } 29
30. import SnapshotTesting func testButtonConfiguration() { let button = UIButton.primaryButton assertSnapshot(matching: button, as: .image) } Snapshot Testing checks for every property of a view, even the ones you don't know about. 30
31. testPrimaryButtonAppearance.1.png 31
32. If something goes wrong... 32
33. If something goes wrong... 33
34. Snapshots can visualize style guides 34
35. Other stuff can have snapshots, too 35
36. func testNetworkCall() { let request = URLRequest() // ... assertSnapshot(matching: request, as: .curl) } curl \ --header "Authorization: Bearer eyJhbGciOiJSUzI1NiIsInR5cCIgOi" \ "https: //example.org/users/234" 36
37. Input Output Views / View Controllers Image Views / View Controllers View Hierarchy URLRequest cURL Request Codable JSON/XML Text Lines Functions with exhaustive input CSV Anything Dump 37
38. Swift https:/ /github.com/pointfreeco/swift-snapshot-testing Kotlin https:/ /github.com/Karumi/KotlinSnapshot http:/ /kotlin-snapshot.karumi.com 38
39. What else? • SwiftCheck • Quick/Nimble • Monkey Tests 39
41. print("Thank You") var questions: Any? 41