Modularizing Legacy Projects Using TDD

Improve current or new projects with top notch testability and maintainability. Writing tests improves the design of your apps, as it pushes you to have a more modularized design. This in turn improves the maintainability and sustainability of your apps. This book is for iOS developers who already know the basics of iOS and Swift development but want to learn all the testing pro features in iOS.

You'll start by reviewing the TDD Cycle and how to implement these concepts on a legacy project or a new one. You'll then walk through TDD step-by-step on a blank project, including setting up test targets, assertions, and expectations. You'll follow that with all levels of testing such as unit tests, integration tests, and end-to-end tests, and also tackle fairly complex, yet badly written legacy code.

The book will take you through the journey of modularizing a legacy app using TDD. Throughout this journey, you will be introduced to multiple testing concepts and techniques, like writing tests for network and core data layers. You will write tests to ensure the thread safety of your app. And you’ll add a new feature while you are in the middle of refactoring, which is an important skill so you can keep adding features while you are fixing your technical debt. By the end of this book, you will have all the tools needed to become a testing master.

WHAT YOU'LL LEARN

* Use mocking and dependency injection to make components more testable


* Write tests for asynchronous code like network code


* Add new features to existing legacy apps using TDD



WHO THIS BOOK IS FOR

Experienced iOS developers who care about software quality and meeting customer expectations. Khaled El-Morabea

Khaled is an engineering manager at Instabug. He has been an iOS developer for more than 8 years and leading the iOS team for more than 3 years. In that time he has worked on several projects. During his time at Instabug, he has worked on multiple integral products, both as a developer and as a strategic engineering manager.

Hassaan El-Garem Hassaan has been involved in the field of iOS Development for 5 years, during which he worked on multiple apps and projects. He has a passion for testing and for working on complex projects, while maintaining the highest level of quality. Following his passion for testing has led him to create a closed-source testing framework used for randomized stress testing.

Chapter 1: Introduction

Why write tests?

Levels of testing

Overview of TDD

Chapter 2: Your First Test

Basics of testing in iOS

XCTest

Code Examples

Chapter 3: The Testing Pyramid

Testing Level Values

Distributing tests along levels

Chapter 4: TDD Deep Dive

Core concepts

Complex examples

Implement projects from scratch with TDD

Chapter 5: Modularization for the Win

Introducing a legacy project

Transform with maintainability

Break up larger components

Apply TDD for modularization

Chapter 5: Dependency Injection and Mocks

Write tests for a component

Downsides of these techniques

Deciding when to apply

Chapter 6: Avoiding Threading Nightmares

Threading issues

Simulate situations

Determine which components need to have multithreading tests

Chapter 7: Testing Your Network Layer

Testing network code c

Differences between sync and async code

Test network code

Chapter 8: Taming CoreData

Core Data

Testing Core Data layer

Chapter 9: Adding Features to Legacy Apps

Testing concepts and techniques

Add a feature to an existing application

TDD and modularization

Modify a tested and modularized project

Chapter 10: Handling Production Issues

Improve the application quality

Make sure that similar problems don't happen again

Tools used to identify and keep track of bugs and crashes.

Add tests for every production issue discovered

Chapter 11: Performance Testing

Write performance tests

MetricKit

Value of performance testing

Write performance tests for iOS applications