Book Image

Test-Driven iOS Development with Swift 4 - Third Edition

By : Dr. Dominik Hauser
Book Image

Test-Driven iOS Development with Swift 4 - Third Edition

By: Dr. Dominik Hauser

Overview of this book

Test-driven development (TDD) is a proven way to find software bugs early. Writing tests before you code improves the structure and maintainability of your apps. Using TDD, in combination with Swift 4's improved syntax, means there is no longer any excuse for writing bad code. This book will help you understand the process of TDD and how to apply it to your apps written in Swift. Through practical, real-world examples, you’ll learn how to implement TDD in context. You will begin with an overview of the TDD workflow and then delve into unit-testing concepts and code cycles. You will also plan and structure your test-driven iOS app, and write tests to drive the development of view controllers and helper classes. Next, you’ll learn how to write tests for network code and explore how the test-driven approach—in combination with stubs—helps you write network code even before the backend component is finished. Finally, the book will guide you through the next steps to becoming a testing expert by discussing integration tests, Behavior Driven Development (BDD), open source testing frameworks, and UI Tests (introduced in Xcode 9).

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Table of Contents (9 chapters)
Preface
Preface
What this book covers
What you need for this book
Who this book is for
Conventions
Reader feedback
Customer support
Free Chapter
1
Your First Unit Tests
Your First Unit Tests
Building your first automatic unit test
Understanding TDD
TDD in Xcode
The advantages of TDD
The disadvantages of TDD
What to test
Summary
2
Planning and Structuring Your Test-Driven iOS App
Planning and Structuring Your Test-Driven iOS App
The task list view
The task detail view
The task input view
The structure of the app
Getting started with Xcode
Setting up useful Xcode behaviors for testing
Summary
3
A Test-Driven Data Model
A Test-Driven Data Model
Implementing the ToDoItem struct
Implementing the Location struct
Implementing the ItemManager class
Summary
4
A Test-Driven View Controller
A Test-Driven View Controller
Implementing ItemListViewController
Implementing ItemListDataProvider
Implementing DetailViewController
Implementing InputViewController
Summary
5
Testing Network Code
Testing Network Code
Implementing tests using a web service
Implementing a login request
Handling errors
Summary
6
Putting It All Together
Putting It All Together
Connecting parts
Serialization and deserialization
Functional tests
Summary
7
Code Coverage
Code Coverage
Enabling code coverage
Automatic deployment with fastlane
Summary
8
Where to Go from Here
Where to Go from Here
What you have learned so far
Integration tests
UI tests
Behavior-Driven Development
TDD in existing projects
Generating mocks with Sourcery
More information about TDD
Summary

Implementing tests using a web service

In the previous chapter, we wrote a stub for CLGeocoder. Now, we will write a test that asserts that the geocoder built into CoreLocation works as we expect it to. The fetching of coordinates from a geocoder is asynchronous. This means that we have to write a test that can deal with asynchronous interfaces.

Let's first structure the files a bit in the Project Navigator of Xcode. Select all the controller files in the main target (ItemListViewController.swift, ItemListDataProvider.swift, ItemCell.swift, DetailViewController.swift, and InputViewController.swift), and press ctrl + click to create a group from the selection. Let's call this group Controller. Do the same with the corresponding test cases in the test target.

Now, let's get started with the test. We start naively by adding the following test to InputViewControllerTests...

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