Book Image

Hands-On Dependency Injection in Go

By : Corey Scott
Book Image

Hands-On Dependency Injection in Go

By: Corey Scott

Overview of this book

Hands-On Dependency Injection in Go takes you on a journey, teaching you about refactoring existing code to adopt dependency injection (DI) using various methods available in Go. Of the six methods introduced in this book, some are conventional, such as constructor or method injection, and some unconventional, such as just-in-time or config injection. Each method is explained in detail, focusing on their strengths and weaknesses, and is followed with a step-by-step example of how to apply it. With plenty of examples, you will learn how to leverage DI to transform code into something simple and flexible. You will also discover how to generate and leverage the dependency graph to spot and eliminate issues. Throughout the book, you will learn to leverage DI in combination with test stubs and mocks to test otherwise tricky or impossible scenarios. Hands-On Dependency Injection in Go takes a pragmatic approach and focuses heavily on the code, user experience, and how to achieve long-term benefits through incremental changes. By the end of this book, you will have produced clean code that’s easy to test.
Table of Contents (15 chapters)

Summary

In this chapter, we have examined DI with method injection, perhaps the most ubiquitous of all forms of DI.

When it comes to extracting dependencies from existing code, for the purposes of testing, it might be the method that first comes to mind. Please be careful with this, we do not want to introduce test-induced damage.

Adding parameters to an exported API function for the sole purpose of testing undoubtedly damages UX code. Thankfully, there are some tricks available to us to avoid damaging our API. We can define member functions that only exist in test code. We can also use Just-In-Time (JIT) dependency injection, which we will examine in Chapter 9, Just-in-Time Dependency Injection.

In this chapter, we have looked at the fantastic and powerful context package. You might be surprised to learn that there is even more value we can extract from this package. I encourage...