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)

The Test Pyramid

Let's start the discussion about testing along the lines of the test pyramid (the test pyramid can be traced back to Mike Cohn's book "Succeeding with Agile" from 2009) in the following figure, which is a metaphor that helps us to decide how many tests and of which type we should aim for:

Figure 7.1: According to the test pyramid, we should create many cheap tests and fewer expensive ones

The basic statement is that we should have high coverage of fine-grained tests that are cheap to build, easy to maintain, fast-running, and stable. These are unit tests verifying that a single "unit" (usually a class) works as expected.

Once tests combine multiple units and cross-unit boundaries, architectural boundaries, or even system boundaries, they tend to become more expensive to build, slower to run, and more brittle (failing due to some configuration error instead of a functional error). The pyramid tells us that the more expensive those...