Book Image

Get Your Hands Dirty on Clean Architecture - Second Edition

By : Tom Hombergs
4 (1)
Book Image

Get Your Hands Dirty on Clean Architecture - Second Edition

4 (1)
By: Tom Hombergs

Overview of this book

Building for maintainability is key to keep development costs low (and developers happy). The second edition of "Get Your Hands Dirty on Clean Architecture" is here to equip you with the essential skills and knowledge to build maintainable software. Building upon the success of the first edition, this comprehensive guide explores the drawbacks of conventional layered architecture and highlights the advantages of domain-centric styles such as Robert C. Martin's Clean Architecture and Alistair Cockburn's Hexagonal Architecture. Then, the book dives into hands-on chapters that show you how to manifest a Hexagonal Architecture in actual code. You'll learn in detail about different mapping strategies between the layers of a Hexagonal Architecture and see how to assemble the architecture elements into an application. The later chapters demonstrate how to enforce architecture boundaries, what shortcuts produce what types of technical debt, and how, sometimes, it is a good idea to willingly take on those debts. By the end of this second edition, you'll be armed with a deep understanding of the Hexagonal Architecture style and be ready to create maintainable web applications that save money and time. Whether you're a seasoned developer or a newcomer to the field, "Get Your Hands Dirty on Clean Architecture" will empower you to take your software architecture skills to new heights and build applications that stand the test of time.
Table of Contents (18 chapters)

Testing a use case with unit tests

Going a layer outward, the next architecture element to test is the use cases implemented as domain services. Let’s look at a test for SendMoneyService, discussed in Chapter 5, Implementing a Use Case. The Send money use case withdraws money from the source account and deposits it into the target account. We want to verify that everything works as expected when the transaction succeeds:

To make the test a little more readable, it’s structured into given/when/then sections, which are commonly used in Behavior-Driven Development.

In the given section, we create the source and target Account objects and put them into the correct state with some methods whose names start with given...(). We also create a SendMoneyCommand object to act as input to the use case. In the when section, we simply call the sendMoney() method to invoke the use case. The then section asserts that the transaction was successful and verifies...