iOS Unit Testing by Example: XCTest Tips and Techniques Using Swift

Description

Fearlessly change the design of your iOS code with solid unit tests. Use Xcode's built-in test framework XCTest and Swift to get rapid feedback on all your code - including legacy code. Learn the tricks and techniques of testing all iOS code, especially view controllers (UIViewControllers), which are critical to iOS apps. Learn to isolate and replace dependencies in legacy code written without tests. Practice safe refactoring that makes these tests possible, and watch all your changes get verified quickly and automatically. Make even the boldest code changes with complete confidence. Manual code and UI testing get slower the deeper your navigation hierarchy goes. It can take several taps just to reach a particular screen, never mind the actual workflow tests. Automatic unit testing offers such rapid feedback that it can change the rules of development. Bring testing to iOS development, even for legacy code. Use XCTest to write unit tests in Swift for all your code. iOS developers typically reserve unit tests for their model classes alone. But that approach skips most of the code common to iOS apps, especially with UIViewControllers. Learn how to unit test these view controllers to expand your unit testing possibilities. Since good unit tests form the bedrock for safe refactoring, you're empowered to make bold changes. Learn how to avoid the most common mistakes Swift programmers make with the XCTest framework. Use code coverage to find holes in your test suites. Learn how to identify hard dependencies. Reshape the design of your code quickly, with less risk and less fear. Cover Table of Contents Foreword Preface How This Book Is Organized Disclaimer: No SwiftUI Support Online Resources Acknowledgments Part I—Foundations 1. Assert Yourself What Are Unit Tests Anyway? Create a Place to Play with Tests Write Your First Assertion Add a Descriptive Message Avoid Conditionals in Tests Describe Objects upon Failure Test for Equality Test Equality with Optionals Fudge Equality with Doubles and Floats Avoid Redundant Messages Choose the Right Assertion Key Takeaways Activities What’s Next? 2. Manage Your Test Life Cycles Make a New Place to Play Start from Test Zero Hook Up Tests to Production Code Examine Console Output Observe Object Life Cycles to Learn the Phases of a Test The Wrong Way to Reduce Duplicate Test Code Learn How XCTest Manages Test Cases Use setUp() and tearDown() Key Takeaways Activities What’s Next? 3. Measure Code Coverage and Add Tests Make a New Place to Play Enable Code Coverage Examine Code Coverage Results Drill into a Partially Covered Line Add Tests for Existing Code Cover a Conditional Cover a Loop Cover Statements in a Sequence Avoid Percentage Targets, Embrace Forward Movement Key Takeaways Activities What’s Next? 4. Take Control of Application Launch Make a New Place to Play Observe the Default Behavior Learn About the Test Launch Sequence Bypass the Normal App Delegate Put Up with the Initial View Controller Tweak Your Testing App Delegate Key Takeaways Activities What’s Next? 5. Load View Controllers Make a New Place to Play Set Up a Storyboard-Based View Controller for Experiments Load a Storyboard-Based View Controller Set Up a XIB-Based View Controller for Experiments Load a XIB-Based View Controller Set Up a Code-Based View Controller for Experiments Load a Code-Based View Controller Key Takeaways Activities What’s Next? 6. Manage Difficult Dependencies Be Okay with Problem-Free Dependencies Identify Difficult Dependencies Create Boundaries to Isolate Dependencies Make a New Place to Play Add Backdoors to Singletons You Own Subclass and Override: A Legacy Code Technique Inject Instances Through Initializers or Properties Inject Closures to Make New Instances Key Takeaways Activities What’s Next? Part II—iOS Testing Tips and Techniques 7. Testing Outlet Connections Make a New Place to Play Test Outlet Connections Check the Effectiveness of Failure Messages Key Takeaways Activities What’s Next? 8. Testing Button Taps (Using Actions) Make a Place to Play with a Button Test Button Taps Make a Test Helper for Button Taps Key Takeaways Activities What’s Next? 9. Testing Alerts Make a New Place to Play Add the Helper Framework to the Project Test Alerts Using the Alert Verifier Move the SUT into the Test Fixture Add Tests for Alert Buttons Key Takeaways Activities What’s Next? 10. Testing Navigation Between Screens Make a New Place to Play Set Up Code-Based Navigation Set Up Segue-Based Navigation Test Code-Based Push Navigation Test Code-Based Modal Presentation Test Segue-Based Push Navigation Test Segue-Based Modal Navigation Key Takeaways Activities What’s Next? 11. Testing UserDefaults (with Fakes) Make a New Place to Play Isolate UserDefaults with Dependency Injection Extract a Protocol to Support Test Doubles Make a Fake Object Test UserDefaults Key Takeaways Activities What’s Next? 12. Testing Network Requests (with Mocks) Make a New Place to Play Isolate URLSession with Dependency Injection Extract a URLSession Protocol for Test Doubles Make a Test Spy Design the Test Case Promote the Test Spy into a Mock Object Improve Mock Object Reporting Key Takeaways Activities What’s Next? 13. Testing Network Responses (and Closures) Make a New Place to Play Parse the Response Start with a Fresh Test Spy Design the Test Case Test Asynchronous Code Keep Asynchronous Code in Its Closure Test an Error Scenario Key Takeaways Activities What’s Next? 14. Testing Text Fields (and Delegate Methods) Make a Place to Play Test the Outlets Test Attributes and Wrangle UIKit Descriptions Test Delegate Methods Test Input Focus Key Takeaways Activities What’s Next? 15. Testing Table Views Make a Place to Play Test Table Views Key Takeaways Activities What’s Next? 16. Testing View Appearance (with Snapshots) Make a Place to Play Add FBSnapshotTestCase to a Test Target Set the Location for Reference Images Write a Snapshot Test See the Difference in a Snapshot Failure Manage Your Snapshot Tests Key Takeaways Activities What’s Next? Part III—Using Your New Power 17. Unleash the Power of Refactoring What Is Refactoring? Lay Out the Views for Our Practice App Add the Code to Our Practice App Replace the Difficult Dependency with a Mock Object Write the First Tests of the Change Password View Controller Test the Cancel Button Test the Submit Button Test the Text Field Delegate Method Refactor to Break Up a Long Function Extract a Method with Parameters Clean Up a Few More Places Key Takeaways What’s Next? 18. Refactoring: Moving to MVVM What Is MVVM? Replace String Literals to Use a View Model Overwrite Storyboard Labels Respond to Changes in the View Model Move Logic into the View Model Key Takeaways What’s Next? 19. Refactoring: Moving to MVP What Is MVP? Set Up the MVP Types Extract Methods into the View Commands Protocol Move a Function into the Presenter Remove the didSet Observer Use Refactoring Principles to Reparent a Swift Type Move Several Functions to the Presenter Extract Password Validation into Its Own Type Finish Up the Refactoring to MVP Key Takeaways What’s Next? 20. Test-Driven Development Beckons to You What Is TDD? Make a New Place to Play with TDD Define the Requirements of the Time-of-Day Greeter Design the First Failing Test with Bare Production Code Make the First Test Pass with “Good Morning” Refactor the First Test to Make It More Expressive Repeat the TDD Steps for the Second Test Add Tests to Expand “Good Afternoon” Implement “Good Evening” Step Back to Refactor the Method as a Whole Add the Name to the Greeting Key Takeaways What’s Next? Bibliography Index – SYMBOLS – – A – – B – – C – – D – – E – – F – – H – – I – – J – – K – – L – – M – – N – – O – – P – – R – – S – – T – – U – – V – – W – – X –