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 Main Paths with System Tests

On top of the pyramid of system tests, a system test starts up the whole application and runs requests against its API, verifying that all our layers work in concert.

In a system test for the "Send Money" use case, we send an HTTP request to the application and validate the response as well as the new balance of the account:

@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)

class SendMoneySystemTest {


  private TestRestTemplate restTemplate;



  void sendMoney() {


    Money initialSourceBalance = sourceAccount().calculateBalance();

    Money initialTargetBalance = targetAccount().calculateBalance();


    ResponseEntity response = whenSendMoney(