Book Image

Get Your Hands Dirty on Clean Architecture

By : Tom Hombergs
Book Image

Get Your Hands Dirty on Clean Architecture

By: Tom Hombergs

Overview of this book

Building for maintainability is key to keeping development costs low and processes easy. 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. With this comprehensive guide, you’ll explore the drawbacks of conventional layered architecture and the advantages of domain-centric styles such as Robert C. Martin's Clean Architecture and Alistair Cockburn's Hexagonal Architecture. Then, you’ll dive into hands-on explanations on how to convert hexagonal architecture into actual code. You'll learn in detail about different mapping strategies between the layers of hexagonal architecture and discover how to assemble the architectural elements into an application. Additionally, you’ll understand how to enforce architecture boundaries, which 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.
Table of Contents (13 chapters)

Testing a Use Case with Unit Tests

Going a layer outward, the next architecture element to test is the use cases. Let's look at a test of SendMoneyService, discussed in Chapter 4, Implementing a Use Case. The SendMoney use case locks the source Account so no other transactions can change its balance in the meantime. If we can successfully withdraw money from the source account, we lock the target account as well and deposit the money there. Finally, we unlock both accounts again.

We want to verify that everything works as expected when the transaction succeeds:

class SendMoneyServiceTest {

  // declaration of fields omitted


  void transactionSucceeds() {


    Account sourceAccount = givenSourceAccount();

    Account targetAccount = givenTargetAccount();