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)

Unnecessary injection

By now, you are probably thinking, there are times when using DI is not the best option, but how do I know when? For this, I would like to offer you another self-survey.

When you are unsure how to proceed, or before you embark on a potentially big refactor, first take a quick run through my DI Survey:

  • Is the dependency an environmental concern (such as logging)?
    Environmental dependencies are necessary but have a tendency to pollute the UX of the function, particularly a constructor. Injecting them is appropriate, but you should prefer a less obtrusive DI method such as JIT injection or config injection.
  • Are there tests in place to protect us during refactoring?
    When applying DI to existing code that has low test coverage, adding some monkey patching will be the smallest change you can make and therefore the one that poses the least risk. Once tests...