Git is the most popular revision control system. For that reason, all the code used in this book is stored in Bitbucket (https://bitbucket.org/). If you don't have it already, install Git. Distributions for all the popular operating systems can be found at http://git-scm.com.

Many graphical interfaces are available for Git; some of them being Tortoise (https://code.google.com/p/tortoisegit), Source Tree (https://www.sourcetreeapp.com), and Tower (http://www.git-tower.com/).

Even though they are outside the topic of this book, virtual machines are a powerful tool and a first-class citizen in a good development environment. They provide dynamic and easy-to-use resources in isolated systems so they can be used and dropped at the time we need them. This helps developers to focus on their tasks instead of wasting their time creating or installing required services from scratch. This is the reason why virtual machines have found room in here. We want to take advantage of them to keep you focused on the code.

In order to have the same environment no matter the OS you're using, we'll be creating virtual machines with Vagrant and deploying required applications with Docker. We chose Ubuntu as a base operating system in our examples, just because it is a popular, commonly used Unix-like distribution. Most of these technologies are platform-independent, but occasionally you won't be able to follow the instructions found here because you might be using...

With time, code tends to grow both in complexity and size. This occurs in the software industry by its nature. All products evolve constantly and new requirements are made and implemented across a product's life. Build tools offer a way to make managing project life cycle's as straightforward as possible, by following a few code conventions such as the organization of your code in a specific way and usage of naming a convention for your classes or a determined project structure formed by different folders and files.

Some of you might be familiar with Maven or Ant. They are a great couple of Swiss army knives for handling projects, but we are here to learn so we decided to use Gradle. Some of the advantages of Gradle are reduced boiler plate code, resulting in a much shortdr file and a more readable configuration file. Among others, Google uses it as its build tool. It is supported by IntelliJ IDEA and is quite easy to learn and work with. Most of the functionalities and tasks...

As many tools and technologies will be covered, we recommend using IntelliJ IDEA as the tool for code development. The main reason is that this IDE works without any tedious configuration. The Community Edition (IntelliJ IDEA CE) comes with a bunch of built-in features and plugins that make coding easy and efficient. It automatically recommends plugins that can be installed depending on the file extension. As IntelliJ IDEA is the choice we made for this book, you will find references and steps referring to its actions or menus. Readers should find a proper way to emulate those steps if they are using other IDEs. Refer to https://www.jetbrains.com/idea/ for instructions on how to download and install IntelliJ IDEA.

In this section, two of the most used Java frameworks for unit testing are shown and briefly commented on. We will focus on their syntax and main features by comparing a test class written using both JUnit and TestNG. Although there are slight differences, both frameworks offer the most commonly-used functionalities, and the main difference is how tests are executed and organized.

Let's start with a question. What is a test? How can we define it?

In the programming approach, there are several types of tests depending on their scope: functional tests, acceptance tests, and unit tests. Further on, we will explore each of those types of tests in more detail.

Unit testing is about testing small pieces of code. Let's see how to test a single Java class. The class is quite simple,...

In the previous section, we gave an overview of what a unit test is and how it can be written using two of the most commonly used Java frameworks. Since tests are an important part of our projects, why not improve the way we write them? Some cool projects emerged, aiming to empower the semantic of tests by changing the way assertions are made. As a result, tests are more concise and easier to understand.

testCompile 'org.hamcrest:hamcrest-all:1.3'